Characterize Eruptive Processes at Yucca Mountain, Nevada Rev 00, ICN 00

ANL-MGR-GS-000002

April 2000

1. PURPOSE 
This Analysis/Model Report (AMR), Characterize Eruptive Processes at Yucca Mountain, 
Nevada, presents information about natural volcanic systems and the parameters that can be used 
to model their behavior. This information is used to develop parameter-value distributions 
appropriate for analysis of the consequences of volcanic eruptions through a potential repository 
at Yucca Mountain. Within the framework of the Disruptive Events Process Model Report 
(PMR), this AMR provides information for the calculations in two other AMRs (CRWMS M&O 
2000a and b); parameters described herein are directly used in calculations in these reports (e.g., 
using the ASHPLUME atmospheric dispersal code in CRWMS M&O (2000b,)) and will be used 
in Total System Performance Assessment (TSPA). Compilation of this AMR was conducted as 
defined in the Development Plan (CRWMS M&O 1999a), except as noted below. 
The report begins with considerations of the geometry of volcanic feeder systems, which are of 
primary importance in predicting how much of a potential repository would be affected by an 
eruption. This discussion is followed by one of the physical and chemical properties of the 
magmas, which influences both eruptive styles and mechanisms for interaction with radioactive 
waste packages. Eruptive processes including the ascent velocity of magma at depth, the onset 
of bubble nucleation and growth in the rising magmas, magma fragmentation, and velocity of the 
resulting gas-particle mixture are then discussed. The duration of eruptions, their power output, 
and mass discharge rates are also described. The next section summarizes geologic constraints 
regarding the interaction between magma and waste packages. Finally, we discuss the bulk grain 
size produced by relevant explosive eruptions and grain shapes. 
Section 3.1 of the Development Plan (CRWMS M&O 1999a) contains the following statements: 
“The report will describe the entrainment of radioactive waste particles by 
ascending magma.” 
“...the report will describe the chemical and mineralogical forms of ash and waste 
that are deposited.” 
Section 3.3 of the same Development Plan contains the following statements: 
“Synthesize information from Project and external sources to describe the 
entrainment of radioactive waste within ascending magma or pyroclastic material 
at Yucca Mountain, including particle size, shape, and density.” 
“Properties to be addressed include ... waste particle characteristics. In addition, 
information on environmental conditions will also be required.” 
Information pertaining specifically to waste (composition, particle size, and entrainment by 
rising magma) and to environmental conditions (e.g., wind velocities) are not described in this 
AMR but in CRWMS M&O (2000b).

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Section 12.0 of the same Development Plan (CRWMS M&O 1999a) states that the only 
computer software used in this AMR will be the ASHPLUME code. However, ASHPLUME is 
not used here but is described in CRWMS M&O (2000b).

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2. QUALITY ASSURANCE 
The activities documented in this AMR were evaluated in accordance with QAP-2-0, Conduct of 
Activities, and were determined to be subject to the requirements of the U.S. Department of 
Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM) Quality Assurance 
Requirements and Description (QARD) (DOE 2000). This evaluation is documented in 
CRWMS M&O 1999b and in Activity Evaluation for Work Package WP 1401213DM1 
(attachment in Wemheuer 1999). This AMR has been prepared in accordance with procedure 
AP-3.10Q, Analyses and Models. The conclusions in this AMR do not affect the repository 
design or permanent items as discussed in QAP-2-3, Classification of Permanent Items.

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3. COMPUTER SOFTWARE AND MODEL USAGE 
Standard, built-in functions of Microsoft Excel, V5.0a, for Macintosh were used to calculate 
parameters in Tables 2, 3, and 4. All other calculations were done using a hand-held calculator. 
No numerical models were used to produce this report.

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4. INPUTS 
In this AMR, pertinent scientific literature is reviewed and some simple theoretical concepts are 
developed. This information is used to suggest parameter distributions for use in Yucca 
Mountain Site Characterization Project (YMP) TSPA calculations. Where possible, parameter 
distributions are based on data or models available in published sources. In cases for which there 
are insufficient published data, parameter distributions are suggested that conservatively capture 
the expected range based on the judgement of the authors. 
4.1 DATA AND PARAMETERS 
Locations and brief descriptions of data and assumed values that were used as input for this 
AMR are listed in Table 1a. Locations and descriptions of information inputs to support 
methodologies, assumptions, and calculations in this AMR are listed in Table 1b and discussed 
in Section 5. Qualification status of the inputs is indicated in the Document Input Reference 
System database. 
Table 1a. Summary of Data Used as Inputs for Calculations in this AMR 
Data Used Application of Data Data Sources Location in this AMR 
45 chemical analyses of 
products from Lathrop 
Wells volcano. 
Calculation of mean chemical 
composition of Lathrop Wells 
products. 
DTN: 
LA000000000099.002 
Section 6.2.1 
Xenolith contents at Alkali 
Buttes and Volcano Hill. 
Discussion of geologic 
constraints on entrainment of 
waste. 
DTN: 
LAGV831812AQ97.001 
Section 6.4 
Table 1b. Summary of Sources of Information Used as Technical Product Inputs 
to Support Methodologies, Assumptions, and Calculations in this AMR 
Information Used Application of Information Sources Location in this AMR 
Discussion of Lathrop 
Wells volcano conduit 
diameter. Xenolith (lithic) 
content at Lathrop Wells 
volcano. 
Development of distribution of 
conduit diameters for potential 
volcano in Yucca Mountain 
Region. Discussion of 
entrainment of waste during a 
potential eruption. 
Doubik and Hill (1999, 
pp. 60–61) 
Sections 6.1, 6.4 
Diameter of Grants Ridge 
plug. 
Development of distribution of 
conduit diameters for potential 
volcano in Yucca Mountain 
Region. 
Keating and Valentine 
(1998, p. 41); 
Woldegabriel et al. 
(1999, p. 392) 
Section 6.1 
Dike width measurements 
in Yucca Mountain 
Region. Ratios of fallout 
sheet volume to cone 
volume for violent 
strombolian eruptions. 
Comparison with dike width 
distribution suggested in this 
AMR. Discussion of 
characteristics of fallout and 
cone deposits from violent 
strombolian eruptions. 
Crowe et al. (1983, pp. 
266, 272) 
Section 6.1, 6.5.1 
Experimental constraints 
on water content of 
basaltic magmas. 
Constraints in developing 
distribution for water content of 
potential volcano in Yucca 
Mountain Region. 
Knutson and Green 
(1975, Fig. 1, p. 126) 
Section 6.2.2, 6.2.4

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Table 1b (continued) 
Relationship between 
temperature and 
composition for basaltic 
magmas. 
Calculation of temperatures of 
magmas forming potential 
Yucca Mountain Region 
volcanoes. 
Sisson and Grove 
(1993a, pp. 163, 167) 
Sections 6.2.2, 6.2.4 
Composition of gases 
from eight historically 
active volcanoes. 
Calculation of mean gas 
composition and associated 
uncertainty. 
Symonds et al. (1994, 
Tables 3–5) 
Section 6.2.3 
Equation relating water 
saturation to pressure in 
basaltic magmas. 
Calculation of saturation 
pressures, exsolution depths, 
and volume fraction of gas in 
magma as a function of 
pressure. 
Jaupart and Tait (1990, 
p. 219) 
Sections 6.2.4, 6.3.2 
Method for calculating 
magma viscosity as a 
function of composition. 
Calculation of viscosities of 
magmas forming potential 
Yucca Mountain Region 
volcanoes. 
Shaw (1972, pp. 873, 
878) 
Section 6.2.4 
Equation for density of 
basic magmas. 
Calculation of magma density 
for potential Yucca Mountain 
Region volcanos. 
Ochs and Lange (1999, 
p. 1314, Eq. 2) 
Section 6.2.4 
Estimate of magma flow 
rate necessary to form aa 
lavas. 
Discussion of constraints on 
magma discharge rates at 
Yucca Mountain Region 
volcanoes. 
Rowland and Walker 
(1990, p. 626) 
Section 6.3 
Theoretical equations and 
results describing the 
ascent of basaltic 
magmas. 
Equation for velocity of magma 
below exsolution depths, 
relationship between magmagas 
mixture density and water 
mass fraction, plots of eruption 
velocity as a function of initial 
water content of magmas. 
Wilson and Head (1981, 
pp. 2974, 2983, Eqs. 
16–18) 
Sections 6.3.1, 6.3.3, 
Figs. 3, 4 
Review of studies on the 
volume fraction of gas in a 
magma at which the 
magma fragments. 
Discussion of magma 
fragmentation criteria. 
Mader (1998, pp. 
55–56) 
Section 6.3.2 
Data on volumes and 
durations of scoria 
(cinder) cone-forming 
eruptions. 
Constraints on duration of 
potential volcanic eruptions in 
Yucca Mountain Region. 
Wood (1980, p. 402) Section 6.3.4 
Duration and power output 
of explosive eruptive 
phases at Cerro Negro, 
Hekla, Tolbalchik, 
Paricutin, and Heimaey 
volcanoes. 
Calculation of mass discharge 
rates of explosive eruptive 
phases. 
Jarzemba (1997, p. 
136) 
Section 6.3.4 
Bulk grain size for 
eruptions at Cerro Negro, 
Tolbachik, and Mount 
Etna. 
Estimation of statistics of grain 
size distributions for explosive 
basaltic eruptions. 
Maleyev and Vande- 
Kirkov (1983, pp. 
61–62); Rose et al. 
(1973, p. 342); 
McGetchin et al. (1974, 
p. 3264) 
Section 6.5.1 
Estimated bulk density of 
pyroclastic fallout 
deposits. 
Recommendations for treatment 
of bulk deposit density in 
consequence analyses. 
Blong (1984, p. 208); 
Sparks et al. (1997, p. 
366) 
Section 6.5.3

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4.2 CRITERIA 
No criteria applicable to this analysis have been identified. This AMR complies with the DOE 
interim guidance (Dyer 1999). Subparts of the interim guidance that apply to this analysis are 
those pertaining to the characterization of the Yucca Mountain site (Subpart B, Section 15), the 
compilation of information regarding geology of the site in support of the License Application 
(Subpart B, Section 21(c)(1)(ii)), and the definition of geologic parameters and conceptual 
models used in performance assessment (Subpart E, Section 114(a)). 
4.3 CODES AND STANDARDS 
No codes or standards apply to this analysis, which involves no design or construction.

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5. ASSUMPTIONS 
Our analyses are based on the assumption that a plausible future eruption (during the postclosure 
performance period) would be of the same character as Quaternary basaltic eruptions in the 
Yucca Mountain region (YMR). Eruptive styles and magmatic composition recorded at the 
Lathrop Wells volcano, the most recent in the region, are emphasized. Another overall 
assumption is that the event probabilities established in CRWMS M&O (2000c) pertain to the 
formation of a new volcano, and that a new volcano will contain some combination of scoria 
cone, spatter cones, and lava cones on the surface, and one or more dikes in the subsurface. 
Assumptions specific to each component of this report are described in the main text of Section 6 
and are summarized below with corresponding section numbers. 
1. Assumption: Data from analog sites provide a basis for estimating probability 
distributions related to the dimensions and geometry of volcanic plumbing for a 
plausible future (during postclosure performance period) formation of a new 
volcano. For conduit diameter, information from Tolbachik and Grants Ridge 
volcanoes is used to constrain the mean and maximum values. Dike-width 
distribution is based on data from dikes exposed in the YMR. Probability 
distribution for the number of dikes that would accompany formation of a new 
volcano is drawn from data on YMR volcanoes and intrusive suites. This 
assumption is discussed in Section 6.1. 
Sources of assumed values: Doubik and Hill (1999, pp. 60–61); Keating and 
Valentine (1998, p. 41); Woldegabriel et al. (1999, p. 392); Crowe et al. (1983, 
pp. 266, 272). 
Rationale: Direct data on the plumbing of the Lathrop Wells volcano are not 
available, so either theoretical estimates or data from analog sites must be relied 
upon. Theoretical estimates are not as reliable as analog data because general 
theories that account for all the complexities of magma intrusion at shallow depth 
do not exist. 
Need for verification: Verification is not required because this assumption is 
based on the best available information, as discussed in Section 6.1. Additional 
information would negligibly affect the analysis. 
2. Assumption: The most likely future eruptive event will have a magmatic 
chemical composition that is adequately represented by the mean composition of 
products of the Lathrop Wells volcano. This assumption is discussed in Section 
6.2.1. 
Rationale: Lathrop Wells volcano is well characterized chemically and represents 
relatively violent eruptions in the YMR, therefore this assumption is conservative 
from a perspective of potential atmospheric dispersal of waste by an eruption.

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Need for verification: Verification is not required because additional data should 
negligibly alter the mean composition values and, therefore, would not affect the 
conservatism inherent in the assumption. 
3. Assumption: Information on inferred eruptive styles, mineralogy, and 
crystallinity of Quaternary YMR basalts, combined with experimental studies on 
magmas of similar composition, constrain the water content of a plausible future 
eruption. This assumption is discussed in Section 6.2.2. 
Sources of assumed values: Knutson and Green (1975, Fig. 1, p. 126); Sisson and 
Grove (1993a, pp. 163, 167). 
Rationale: Direct measurements of pre-eruptive water content of magmas is very 
difficult, particularly at extinct volcanoes such as the YMR basaltic centers. The 
best approach would be to measure water contents in glass inclusions in 
phenocrysts, although even this method does not necessarily provide complete 
information on pre-eruptive water content. Furthermore, to the knowledge of the 
authors, such data do not exist for YMR basalts. Therefore, the less direct 
estimates using this assumption must be relied on. 
Need for verification: Verification is not needed because this assumption uses the 
best available information, as described in Section 6.2.2. Additional information 
should negligibly affect the analysis. 
4. Assumption: Gas compositions from active volcanoes (Mt. Etna, Momotomgo, 
Poas, Kilauea, Adoukoba, Erta Ale, Nyiragongo, and Surtsey) provide a basis for 
estimating gas composition of a potential new volcano in the YMR. This 
assumption is discussed in Section 6.2.3. 
Sources of assumed values: Symonds et al. (1994, Tables 3–5). 
Rationale: Absence of gas composition data for YMR basalts precludes the use 
of site-specific information. The volcanoes listed above define a range of basaltic 
composition that brackets the YMR basalt values. Therefore, the range of gas 
composition for these volcanoes should include the composition of a potential 
new eruption in the YMR. 
Need for verification: Verification is not needed because this assumption is based 
on the best available information, as described in Section 6.2.3.

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5. Assumption: Pressure in dikes and conduits during eruption is equal to lithostatic 
pressure. This assumption is discussed in Section 6.3.2. 
Sources of assumed values: Jaupart and Tait (1990, p. 219). 
Rationale: Actual pressure is a complex function of the velocity and density of 
the magma as it rises, and of the strength of wall rocks. Because a general model 
for these effects does not exist, lithostatic pressure is used as a first-order 
approximation. 
Need for verification: Verification is not needed because this assumption is based 
on the best available approach, as discussed in Section 6.3.2. 
6. Assumption: The flow of rising magma can be considered homogeneous and 
characterized by equilibrium between melt and exsolved volatiles. This 
assumption is discussed in Section 6.3.2. 
Rationale: Actual velocities of melt and bubbles (exsolved volatiles) are 
different, but a general theory for basaltic magmas is not yet available to account 
for this effect. 
Need for verification: Verification is not needed because this assumption is based 
on the best available approach, as discussed in Section 6.3.2. 
7. Assumption: Fragmentation of rising magma occurs when the volume fraction of 
bubbles exceeds 0.75. This assumption is discussed in Section 6.3.2. 
Sources of assumed values: Mader (1998, pp. 55–56). 
Rationale: This is an established value in the peer-reviewed literature but is used 
only as an approximate value. 
Need for verification: Verification is not needed because this assumption is based 
on the best available approach, as discussed in Section 6.3.2. 
8. Assumption: Data on duration, power output, and grain size of historic eruptions 
of non-YMR volcanoes provide a basis for estimating power and duration of a 
future YMR eruption. This assumption is discussed in Sections 6.3.4. and 6.5.1.

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Sources of assumed values: Crowe et al. (1983, pp. 266, 272); Wood (1980, p. 
402); Jarzemba (1997, p. 136); Maleyev and Vande-Kirkov (1983, pp. 61–62); 
Rose et al. (1973, p. 342); McGetchin et al. (1974, p. 3264). 
Rationale: As no direct data are available for these parameters for explosive 
eruption phases at YMR volcanoes, analog information must be used. 
Need for verification: Verification is not needed because this assumption is based 
on the best available approach, as described in Sections 6.3.4 and 6.5.1. 
9. Assumption: Methods, equations, and discussions in the peer-reviewed literature 
relating to calculations of magma viscosity, density, velocity, and discharge rates 
and of deposit density represent the best inputs to estimate these parameters for a 
new volcano. 
Sources of assumed values: Shaw (1972, pp. 873, 878); Ochs and Lange (1999, p. 
1314, Eq. 2); Rowland and Walker (1990, p. 626); Wilson and Head (1981, pp. 
2974, 2983, Eqs. 16–18); Blong (1984, p. 208); Sparks et al. (1997, p. 366). 
Rationale: As no direct data are available for eruptions at YMR volcanoes, 
approaches from the peer-reviewed literature must be used. 
Need for verification: Verification is not needed because this assumption is based 
on the best available approach, as described in Sections 6.2.4, 6.3, 6.3.1, 6.3.3, 
and 6.5.3.

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6. ANALYSIS/MODEL 
6.1 CHARACTERISTICS OF ERUPTIVE CONDUITS, DIKE WIDTHS, AND DIKE 
SWARMS 
Most observed basaltic eruptions begin as fissure eruptions, discharging magma where a dike 
intersects the Earth’s surface, and they rapidly become focused into semicircular conduit 
eruptions. Some eruptions, such as Paricutin in Mexico (Luhr and Simkin 1993, p. 62), 
originated from single-point sources, although the vent was located on a long fissure that opened 
just before eruption began. The fissure is likely the surface expression of an ascending dike that 
fed the eruptions. Because of the effect of the (1) conduit diameter and (2) depth (to which a 
conduit extends before merging into a simple feeder dike) on the number of waste packages 
disrupted by a potential eruption at Yucca Mountain, it is important to constrain both these 
variables. 
The best potential data for these parameters would come from a study of basaltic volcanic necks 
exposed by erosion in the southwestern United States where direct measurements of conduit 
diameter and its variation with depth could be made. However, such data are lacking; although 
many volcanic necks have been mapped as part of regional studies, they were not measured in 
detail, at least for the range of compositions of interest to the YMP. Without access to direct 
measurements of conduit diameter, estimates of this parameter are based on analog studies (see 
Section 5, Assumption 1). 
Doubik and Hill (1999, pp. 60–61) proposed that the Lathrop Wells conduit may have been as 
wide as 50 m at depths equivalent to repository depth during the last stages of eruption. Their 
estimate was derived from an inferred analogy with modern eruptions at Tolbachik (Kamchatka, 
Russia). The conceptual model is that conduit diameter increases during successive stages of an 
eruption and that the maximum diameter achieved near the end of an eruption is the value of this 
parameter to be considered in evaluating volcanic disruption of a nuclear waste repository. The 
method for calculating conduit diameter of the Tolbachik volcanic vents is based on estimates of 
eruption volume, xenolith content of the pyroclastic deposits, and source depths of the xenoliths. 
By assuming an initial conduit diameter and calculating the volume of country rock removed 
along part of the length of the conduit, one can calculate the progressive enlargement of the 
conduit as the eruption proceeds. 
The 50-m estimate of conduit diameter for Lathrop Wells is large, considering that Doubik and 
Hill (1999, p. 59) calculated a 48-m diameter for the Tolbachik conduit developed during a much 
larger eruption. This result is forced by their assumption that xenoliths at Lathrop Wells were 
derived only from a 550-m thick Tertiary ignimbrite section (compared to a 1.7-km source 
section at Tolbachik; Doubik and Hill 1999, pp. 57, 59), so that the erupted volume of xenoliths 
was derived from a shallower (but wider) conduit. 
In the absence of specific data to test the assumptions made by Doubik and Hill (1999, p. 59), 50 
m is suggested as a median value for conduit diameter at depth for potential eruptions at Yucca 
Mountain. The maximum value for the conduit diameter in the distribution to be used for 
performance assessment (PA) is 150 m, which corresponds to the diameter of the Grants Ridge

ANL-MGR-GS-000002, Rev 00 26 April 2000 
conduit/plug in New Mexico (Keating and Valentine 1998, p. 41; WoldeGabriel et al. 1999, p. 
392). The large size of the Grants Ridge plug reflects that it erupted a volume on the order of a 
few km3 of alkali basalt and, therefore, is expected to be a conservative upper bound for conduit 
diameter (compared, for example, to the Lathrop Wells volcano with its approximate volume of 
108 m3; Crowe et al., 1983, p. 269) for a potential Yucca Mountain eruption. The minimum 
conduit diameter value for a PA realization should be the same as the dike width selected for that 
realization. The distribution should be log normal. This distribution will conservatively capture 
the range of conduit diameters for a potential volcanic event at Yucca Mountain. 
Dike widths should be described with a log normal distribution with a minimum of 0.5 m, a 
mean of 1.5 m, and a 95th percentile width of 4.5 m. This distribution is consistent with data 
reported by Crowe et al. (1983, p. 266), who measured dikes in the YMR. 
Volcanoes in the YMR are fed by one main dike along which a central cone and other vents may 
form, but subsidiary dikes are also present. For example, the Lathrop Wells volcano likely is 
underlain by three dikes (inferred from Perry et al. 1998, Figure 2.10): (1) the dike that fed the 
main cone and small spatter vents in a chain to the north and south of the cone, (2) a dike that fed 
spatter and scoria mounds in a parallel chain just to the east of the main dike, and (3) possibly a 
dike that fed scoria vents near the northern edge of the volcano. In addition, there are likely to 
be small dikes that radiate outward from the main cone’s feeder conduit. The Paiute Ridge 
intrusive complex, which appears to have fed at least one volcanic vent (evidenced by the 
presense of lava-flow remnants and a plug-like body), may have as many as 10 dikes, in addition 
to sill-like bodies (as inferred from examination of Perry et al. 1998, Figures 5.15 and 5.16). To 
account for the likelihood of dike swarms, rather than single dikes, during formation of a new 
volcano, a log normal distribution is recommended for the number of dikes that has a minimum 
value of 1, a mean of 3 (reflecting our assumption that the most likely new volcano will be 
similar to the Lathrop Wells volcano), and a 95th percentile value of 10 (treating Paiute Ridge as 
a large event). 
6.2 CHARACTERISTICS OF IGNEOUS MATERIAL 
6.2.1 Magma Chemistry 
Magma-chemistry data are used to determine parameters for important variables such as 
magmatic viscosity, magma temperature, and density. Two approaches are possible for 
predicting the chemistry of future magmas. The first is to calculate a volume-weighted mean 
composition based on analysis of basaltic rocks from the YMR, which is a method that would 
capture the existing magma chemistry record. A second approach is to use the most recent 
eruption at Lathrop Wells volcano as the one that most likely represents the composition of 
future eruptions. The second approach was selected because it emphasizes the composition that 
produced more violent explosive eruptions compared to other YMR volcanoes (as inferred from 
Perry et al. 1998, Chapter 2); therefore, it is the more conservative of the two approaches 
because it represents a greater potential dispersal of radionuclides (see Section 5, Assumption 2). 
The major element variation for Lathrop Wells is based upon 45 chemical analyses (DTN 
LA000000000099.002). Table 2 gives the statistical parameters associated with these analyses.

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Table 2. Mean Lathrop Wells Lava Chemistry with Associated Statistics 
(All values except count are in weight percent) 
SiO2 TiO2 Al2O3 
Mean 48.50 Mean 1.93 Mean 16.74 
Standard Error 0.09 Standard Error 0.01 Standard Error 0.03 
Median 48.57 Median 1.93 Median 16.75 
Mode 48.55 Mode 1.97 Mode 16.87 
Standard Deviation 0.58 Standard Deviation 0.06 Standard Deviation 0.22 
Sample Variance 0.34 Sample Variance 0.00 Sample Variance 0.05 
Count 45.00 Count 45.00 Count 45.00 
Fe2O3Ta Fe2O3
b FeOb 
Mean 11.63 Mean 1.74 Mean 8.90 
Standard Error 0.03 Standard Error 0.00 Standard Error 0.02 
Median 11.58 Median 1.74 Median 8.86 
Mode 11.56 Mode 1.73 Mode 8.84 
Standard Deviation 0.22 Standard Deviation 0.03 Standard Deviation 0.17 
Sample Variance 0.05 Sample Variance 0.00 Sample Variance 0.03 
Count 45.00 Count 45.00 Count 45.00 
DTN: LA000000000099.002 
NOTES: a Total iron is reported as Fe2O3T 
b Fe2O3 and FeO were recalculated assuming a 0.15 mole fraction of ferric iron (Fe2O3)

ANL-MGR-GS-000002, Rev 00 28 April 2000 
Table 2 (continued). Mean Lathrop Wells Lava Chemistry with Associated Statistics 
MnO MgO CaO 
Mean 0.17 Mean 5.83 Mean 8.60 
Standard Error 0.00 Standard Error 0.02 Standard Error 0.03 
Median 0.17 Median 5.83 Median 8.55 
Mode 0.17 Mode 5.88 Mode 8.41 
Standard Deviation 0.00 Standard Deviation 0.11 Standard Deviation 0.22 
Sample Variance 0.00 Sample Variance 0.01 Sample Variance 0.05 
Count 45.00 Count 45.00 Count 45.00 
Na2O K2O P2O5 
Mean 3.53 Mean 1.84 Mean 1.22 
Standard Error 0.01 Standard Error 0.01 Standard Error 0.00 
Median 3.55 Median 1.84 Median 1.22 
Mode 3.59 Mode 1.84 Mode 1.21 
Standard Deviation 0.09 Standard Deviation 0.04 Standard Deviation 0.03 
Sample Variance 0.01 Sample Variance 0.00 Sample Variance 0.00 
Count 45.00 Count 45.00 Count 45.00 
DTN: LA000000000099.002 
NOTE: The following sample analyses from Perry and Straub (1996, Appendix A) were used to develop the 
statistics in this table: LW11FVP, LW12FVP, LW74FVP, LW45FVP, LW72FVP, LW73FVP, 
LW100FVP, LW120FVP, LW121FVP, LW30FVP, LW31FVP, LW32FVP, LW63FVP, LW64FVP, 
LW65FVP, LW66FVP, LW67FVP, LW110FVP, LW115FVP, LW20FVP, LW21FVP, LW22FVP, 
LW23FVP, LW06FVP, LW07FVP, LW40FVP, LW41FVP, LW44FVP, LW55FVP, LW56FVP, 
LW19FVP, LW25FVP, LW26FVP, LW27FVP, LW28FVP, LW29FVP, LW04FVPA, LW54FVP, 
LW57FVP, LW58FVP, LW05FVPA, LW59FVP, LW60FVP, LW61FVP, LW62FVP. 
6.2.2 Water Content 
Eruptive styles in the YMR ranged from violent strombolian on one end of the spectrum to 
quiescent aa lava on the other as indicated by geologic mapping (Perry et al. 1998, Chapter 2). 
Eruption style is primarily controlled by volatile content (which is dominated by water) and the 
rate at which volatiles are exsolved from the magma. The observed eruptive styles indicate a 
large range in volatile contents and, hence, water of YMR magmas. In addition, variations in 
energy are suggested at individual volcanic centers such as those of the Quaternary Crater Flat 
field and Lathrop Wells volcanoes. 
Amphibole, possibly of magmatic origin, is found as a rare and sparse phase in some Quaternary 
Crater Flat basalts. Knutson and Green (1975, Figure 1, p. 126), performing experiments on 
material similar in composition to YMR basalts, observed that magmatic amphibole was 
stabilized at water contents between 2 and 5 weight percent (wt%). Baker and Eggler (1983, p. 
387) showed that at 2 Kbar pressure, water content in excess of 4.5 wt% is required to stabilize 
amphibole in high-alumina basalt similar to YMR basalts. However, water content substantially 
greater than 5 wt% is not considered likely because this high water content is most commonly

ANL-MGR-GS-000002, Rev 00 29 April 2000 
associated with more chemically evolved magmatic compositions than observed at the YMR. 
Also, Sisson and Grove (1993a, p. 167) note that low-Mg basalts with high alumina content 
cannot erupt as liquids with water content in excess of 4 wt% (by mass) because they will 
exsolve liquid and rapidly crystallize to form phenocryst-rich magmas as they approach the 
surface. Based on this, it is argued that 4 wt% is an upper bound on initial dissolved water 
content. Aa lava, on the other hand, may form from relatively low-volatile-content eruptions. 
Even if one could tie a particular concentration of volatiles to a particular eruptive style, the 
YMR post-Miocene record is sparse; therefore, it is difficult to define rigorously a probability 
distribution function for water content for use in PA (see Section 5, Assumption 3). The 
following distribution is recommended: 
From 0 to 1 wt% water, probability increases linearly such that magma with 0 wt% water has 
a zero probability of occurrence. This reflects our knowledge that very low volatile contents 
are very rare. Between 1 and 3%, the probability should be uniform, reflecting that this is the 
most likely range of water contents but that more specific information is not available. 
Between 3 and 4 wt%, the probability should decrease linearly so that it is zero at 4 wt%, 
representing the expectation that at about 4 wt%, basaltic magmas will crystallize 
underground rather than erupt. 
Direct measurements of water in mafic magmas or magmatic products from a range of tectonic 
settings indirectly support the recommended parameter values and cover the range of values that 
can be reasonably expected for future basaltic igneous activity. Garcia et al. (1989, Table 1, p. 
10527), Byers et al. (1985, Figure 4, p. 1891), and Muenow et al. (1979, Table 1, p. 74) found 
total water contents in Hawaiian tholeiites and transitional alkalic basalts that range from near 0 
to nearly 1%. These melts probably represent higher degrees of partial melting than YMR 
basalts, so their low water contents are expected. On the other hand, Gaetani et al. (1993, pp. 
332–334) and Sisson and Grove (1993b, p. 163) present experimental evidence that high-alumina 
basalt and basaltic andesite magmas commonly contain up to several percent by mass of water. 
Sisson and Layne (1993, Table 1, p. 622) measured water contents in glass inclusions from arc 
basalts and basaltic andesites that range from 1 to 6%. True magmatic values could be 
somewhat lower because of concentration of water in the inclusions, which is caused by partial 
crystallization of the melt after entrapment. Water contents of 0.2 to 2% have been reported for 
back arc basin lavas and 1.2 to 3% for island arc tholeiites and boninites (Danyushevsky et al. 
1993, Tables 1 and 4, pp. 349 and 358). 
6.2.3 Mole Percent of Constituents in Volcanic Gas 
A survey of data compilations from the literature, including volcanoes from convergent, 
divergent, and hot-spot tectonic settings, must suffice to constrain the gas constituents in YMR 
basalts owing to the absence of current activity in the YMR from which gases could be directly 
sampled. Two types of data exist in the literature: (1) measurements of emitted volcanic gases 
and (2) measurements of gases trapped in volcanic glass, or melt inclusions. The first type of 
data is more directly relevant to eruptive scenarios at Yucca Mountain because the gases released 
from an igneous event will include corrosive species. Also, gases will fractionate between the

ANL-MGR-GS-000002, Rev 00 30 April 2000 
magma and the gas phase during exsolution. Consequently, gas composition data for glasses 
may not directly represent their relative abundances in the gas phase after exsolution. 
Measured concentrations of volcanic-gas constituents were taken from a compilation by 
Symonds et al. (1994, Tables 3–5), and only the data for mafic centers were included in the 
present analysis (see Section 5, Assumption 4). Data include hawaiite from Mt Etna; tholeiitic 
basalt from Momotombo, Poas, Kilauea, Ardoukoba, and Erta Ale; nephelenite from 
Nyiragongo; and alkali basalt from Surtsey (Table 3). The Table 3 statistics were calculated by 
first computing the mean for each of the above mentioned volcanic centers from the data in 
Symonds et al. (1994, Tables 3–5) and then using these individual means to generate the overall 
statistics. 
Table 3. Mole Percent Concentration of Volcanic 
Gases and Associated Uncertainty Estimates 
H2O H2 CO2 CO SO2 
MEAN 73.16 1.17 14.28 0.57 9.45 
SQRRT SUM SQRa 17.97 0.89 16.03 0.59 8.90 
STD DEVb 19.81 0.67 15.32 0.75 8.95 
S2 HCl HF H2S fO2
c 
MEAN 0.41 0.87 0.17 0.74 –10.63 
SQRRT SUM SQRa 0.63 0.21 0.04 1.04 1.92 
STD DEVb 0.40 1.12 0.08 0.69 1.80 
Source: Symonds et al. (1994, Tables 3 through 5) 
NOTES: a square root of the sum of the squares of individual standard deviations for 
individual volcanic centers. 
b standard deviation of the individual means for individual volcanic centers 
c fO2 is listed as log bars. 
This is a closed data set, indicating that each parameter (other than fO2) must vary between 0 and 
100%. Clearly, a species such as H2O will rarely be present at levels less than 50% and probably 
has some mean or median value of geologic significance. If data from sufficient eruptions and 
individual volcanoes were gathered, a normal distribution of values seems likely. As for the 
minor species, which are also corrosive, the cited uncertainties are quite large relative to mean 
values. Thus, it seems likely that adequate conservatism will be accommodated by a normal, or 
even a uniform, distribution. 
6.2.4 Magmatic Temperatures, Viscosities, and Densities 
Magmatic temperature is a function of pressure, major-element composition, and water content. 
Many direct measurements of magmatic temperatures have been made for erupting lavas. 
However, this is only possible where water contents are low enough, or rates of magmatic 
outgassing are slow enough, to permit direct measurement. Thus, although direct measurements 
are available for the low end of the spectrum of water content, experiments must be relied on to

ANL-MGR-GS-000002, Rev 00 31 April 2000 
constrain magmatic temperatures for magmas with elevated water content (see Section 5, 
Assumption 9). 
YMR basaltic lavas are generally aphyric to sparsely porphyritic (Perry and Straub 1996, p. 6), 
which indicates that they erupted at near-liquidus or superliquidus temperatures. The liquidus 
for dry basaltic magmas has a positive slope and varies as a function of pressure. Wet liquidi, 
however, have negative slopes, so that water-bearing magmas may exist at a temperature less 
than that of the dry liquidus. Jaupart and Tait (1990, p. 219) present a simple expression for the 
solubility of water in basaltic magma 
n = 6.8 x 10–8P0.7 (Eq. 1) 
where n is the mass fraction of water and P is the pressure in Pascals. Because of the negative 
slope of the basalt solidus, corresponding temperatures on the solidus represent minimum 
liquidus temperatures. As magmas decompress, not only will they tend to exsolve more fluid, 
they will also tend to crystallize. A magma is saturated with respect to water when the pressure 
is such that n equals the initial water content. Table 4 shows saturation pressures, calculated 
from Equation 1, for initial water contents of 0.5, 1.0, 2.0, 3.0, and 4.0 wt% (wt% = 100 times 
the mass fraction). At lower pressures, water vapor would begin to exsolve and form bubbles 
(see also Section 6.3.2 below). 
Using saturation pressures derived from Table 4, the following expression of Sisson and Grove 
(1993a, p. 178) can be used to estimate multiple phase-saturation (liquidus) temperatures in the 
magmas: 
T(°C) = 969 – (33.1 x H2O) + 0.0052 (Pb – 1) + 742.7 x Al# – 138 x NaK# + 125.3 x Mg# 
(Eq. 2) 
where H2O is the wt% of water, Pb is pressure in bars (note that elsewhere in this document 
pressure is in Pascals), Al# is the ratio of mass fractions of Al2O3/(Al2O3 + SiO2), NaK# is the 
ratio of mass fractions of (Na2O + K2O)/(Na2O + K2O + CaO), and Mg# is molar Mg/(Mg + 
2Fe2O3T). It should be noted that Al#, NaK#, and Mg# do not vary as a function of water content 
in Lathrop Wells magmas as these parameters simply express relative proportions. 
Liquidus temperatures for Lathrop Wells magmas with different hypothetical water contents 
were calculated as follows. First, the mean Lathrop Wells composition (from Table 2) was 
normalized to 100% (anhydrous). Then, major element oxides were renormalized to sum to 
99.5, 99.0, 98.0, 97.0, and 96.0 wt%. To these values were added 0.5, 1.0, 2.0, 3.0, and 4.0 wt% 
H2O, respectively, so that the sum of the renormalized major element oxide content and the 
water content sum to 100 wt% in each case. With these new hypothetical compositions, and the 
saturation pressure calculated as described above, Equation 2 was used to compute the liquidus 
temperatures shown in Table 4. The same hypothetical compositions and calculated 
temperatures were used to calculate bubble- and crystal-free viscosity using the method of Shaw 
(1972, pp. 873, 878).

ANL-MGR-GS-000002, Rev 00 32 April 2000 
Density can also be calculated as a function of composition (including water content), pressure, 
and temperature using the formulation and data of Lange and Carmichael (1990, Table 3) with 
additional data for H2O (Ochs and Lange 1999, pp. 1314–1315). Equation 2 from Ochs and 
Lange (1999, p. 1315) produces the molar volume of the silicate liquid, which only requires a 
simple conversion to density. The density conversion can be done as follows: Assume that 100 
g of magma are present. In doing the calculation, one converts the weight of each oxide (which 
is just the wt%) to the number of moles of each constituent. These terms can be summed to give 
a total number of moles. The density is then equal to the inverse of the product of molar volume 
(cm3/mol) and number of moles per 100 g of liquid. This result, in g/cm3, can then be converted 
to kg/m3 as shown in Table 4. 
Table 4. Calculated Saturation Pressures and Temperatures as 
a Function of Water Content for Lathrop Wells Magmas 
Water Content 
(wt%) 
Saturation Pressure 
(Pa) 
Liquidus 
Temperature (°C) 
Viscosity 
(log poise) 
Density 
(kg/m3) 
0 1 x 105 1169 2.678 2663 
0.5 9.0 x 106 1153 2.572 2633 
1 2.4 x 107 1137 2.472 2605 
2 6.5 x 107 1106 2.284 2556 
3 1.2 x 108 1076 2.112 2512 
4 1.7 x 108 1046 1.957 2474 
Derived using mean Lathrop Wells compositions from Table 2. 
A review of some relevant experimental data reveals these values are reasonable. The 
temperature between 1174 and 1188°C is the liquidus temperature for a mildly alkalic basalt 
similar in composition to the mean Lathrop Wells lava composition (Sample 1 of Mahood and 
Baker (1986); composition of Sample 1 is reported in Table 7, and liquidus temperature is the 
temperature above which there are no mineral phases in Table 1 of that paper) and close to the 
temperature reported by Knutson and Green (1975, Figure 1) for a hawaiite that is also similar in 
composition to Lathrop Wells. Yoder and Tilley (1962, Figure 28) published results for watersaturated 
liquidus for a high-alumina basalt. At 1.75 x 108 Pa water pressure, the liquidus was 
more than 100°C cooler than the 105 Pa liquidus temperature. Thus, our calculated parameter 
values are consistent with a well- and long-established body of experimental data. 
6.3 ERUPTIVE PROCESSES 
Quaternary basalts of the YMR display textural and depositional facies that indicate a range of 
eruptive processes. Explosive processes, in which fragments, clots, or melt were erupted in a 
stream of gas, are evidenced by the presence of scoria cones and remnants of ash fallout 
blankets. Effusive processes, in which magma fragmentation did not occur in the feeding 
system, are recorded by the presence of lava flows, although it is also common in basaltic 
eruptions to produce lava flows by the coalescence and remobilization of explosively erupted 
clasts. Within these two broad categories of eruptive facies (explosive and effusive), there are 
further distinctions. Explosively erupted deposits, for example, may display a range of facies

ANL-MGR-GS-000002, Rev 00 33 April 2000 
depending on the local rate of accumulation and on the temperature of clasts when they are 
deposited. Very high accumulation rates of hot (still molten) clasts result in coalescence and 
formation of lava flows. Somewhat lower accumulation rates and temperatures may result in 
welded spatter, in which relicts of individual clasts shapes may still be observed to varying 
degrees. Still lower accumulation rates and temperatures (such that the clasts are still plastic 
upon deposition) result in partly welded spatter, in which clast shapes are quite obvious but the 
deposit is resistant to erosion. Low accumulation rates of very hot clasts result in individual 
spatter clasts that flatten upon deposition but solidify before subsequent clasts are deposited on 
top and, therefore, do not weld. Deposits of nonindurated, brittle cinders (or scoria) result from 
deposition of already-cooled clasts. All of these explosive facies are present to some degree in 
the Yucca Mountain basalts. Effusive lava flows in the YMR are mainly of the aa type, 
indicating relatively high effusion rates (greater than c. 1.5–3 x 104 kg/s; Rowland and Walker 
1990, p. 626) (see Section 5, Assumption 9), although the limited extent of the flows suggests 
relatively short eruption duration. 
The Lathrop Wells volcano is a good example of a range of eruptive processes recorded by a 
single volcano (Perry et al. 1998, Chp. 2). The surface of the main cone is composed mainly of 
loose scoria with a relatively high vesicularity. The cone is surrounded, particularly to the south, 
west, and north, by a fallout blanket up to c. 3 m thick (within 1 km of the cone) composed of the 
same loose scoria. Remnants of this fallout deposit are exposed northward up to 2 km from the 
crater, and ~20 km north of the crater, where its reworked equivalent is exposed in trenches 
excavated across the Solitario Canyon fault (Perry et al. 1998, pp. 4.24–4.30). These features all 
suggest a relatively high-energy eruption with an ash column that rose kilometers into the air so 
that clasts were cool when they fell to the ground and finer ash was dispersed widely by winds 
(termed a “violent strombolian eruption” by many volcanologists). Other parts of the Lathrop 
Wells volcano were emplaced by quite different mechanisms. For example, mounds of coarse, 
partially welded spatter indicate a local, relatively low-energy strombolian eruption. Recent 
quarry exposures reveal welded scoria and agglutinate, typical of a strombolian eruption, in the 
main cone, raising the possibility that only the late stages of the cone-forming eruptions were 
violent strombolian. Thick, stubby aa flows suggest short-duration, high-mass-flux effusive 
eruption. Other volcanoes of the YMR (e.g., Sleeping Butte, Red Cone, Black Cone) are less 
well preserved, but they seem to exhibit a similar range in eruptive styles at individual centers. 
This observation means that it is not representative to assume one eruption mechanism and, 
therefore, one exposure pathway for volcanic disruption of a potential repository. 
The solubilities of volatiles such as H2O and CO2 in basaltic magmas are proportional to 
pressure. At depth (for example, in a magma chamber), magmas will have relatively high 
volatile contents, but as they ascend through progressively lower lithostatic pressure, they will 
become oversaturated and bubbles will nucleate. Continued rise results in increasing numbers 
and sizes of bubbles (caused by combined exsolution of volatiles and decompression and 
coalescence growth of the bubbles); these two processes increase the specific volume of the 
magma, and as a consequence, its velocity also increases gradually (according to conservation of 
mass). Explosive eruption occurs when, at shallow depths, the magma reaches a foamy state 
and, with further decompression, it fragments, switching from being a melt with dispersed 
bubbles to a gas with dispersed fragments or clots of melt. At and above this fragmentation 
depth, the gas-melt mixture accelerates rapidly until it leaves the volcanic vent at speeds of tens

ANL-MGR-GS-000002, Rev 00 34 April 2000 
to a few hundreds of meters per second. A further complication in this sequence of events is the 
possibility of loss of volatiles through the walls of the conduit or dike as magma ascends. This 
action can reduce the effective volatile content for the eruption. 
The dynamics of magma ascent and particularly the fragmentation process are currently a topic 
of intense research in the volcanological community. Most recent advances in this area focus on 
silicic rather than basaltic magmas. The reasons for this are twofold. First, silicic magmas are 
responsible for the most explosive eruptions and present the most severe hazard to populations; 
understanding their dynamics is key in mitigating these hazards. Second, silicic magmas have 
viscosities several orders of magnitude higher than basaltic magmas. This conditon reduces 
greatly the effects of bubbles rising more rapidly than their host melts and coalescing with each 
other. Thus, theoretical modeling is made more tractable by having to consider only nucleation, 
decompression growth, and growth by diffusion of exsolving volatiles into bubbles. In other 
words, the dynamics are closely approximated by a “homogeneous flow” approach, in which the 
gas and melt move at about the same velocity everywhere and are in thermal equilibrium. 
Unfortunately, the rise of basaltic magmas with their lower viscosities is complicated by the 
potential for rapid rise and coalescence of bubbles (Vergniolle and Jaupart 1986, pp. 
12842–12846). Extreme results of this process are represented by classic strombolian bursts, 
which are basically large bubbles rising through and bursting at the top of a magma column, 
producing eruptions of mostly gas with small amounts of melt (fragments of bubble walls) 
thrown out ballistically. Another example is the Hawaiian fire fountain eruptions, which have 
been observed to erupt mixtures with H2O vapor content much higher than the H2O solubility at 
depth. A general theory for the rise of basaltic magmas, accounting fully for the important twophase 
flow effects, does not exist. Instead, the treatment relied on below simplifies the problem 
by assuming homogeneous flow. 
6.3.1 Magma Ascent Rate Below Volatile Exsolution 
Wilson and Head (1981) developed a theory for the ascent of basaltic magmas along dikes and 
cylindrical conduits using the homogeneous flow simplification. At depth, where magma is 
under sufficient pressure that all volatiles are dissolved, the buoyancy-driven ascent velocity, uf, 
is 
u 
A
K r 
gr K 
A f 
m 
c m m = + - .
. . 
.
. .
- 
.
. .. .
. .. 
.
. 
. . . 
. 4 
1 
64 
1 
3 
2 2 
1 2 ( ) / 
(Eq. 3) 
where A = 64 (circular conduit) or 24 (dike), . is magma viscosity, K = 0.01, .m is the melt 
density (no bubbles), .c is the wall rock density, r is the conduit radius or dike half width, and g 
is gravitational acceleration (Wilson and Head 1981, p. 2974) (see Section 5, Assumption 9). 
Note that flow described in Equation 3 can occur only when .c > .m. 
6.3.2 Volatile Exsolution and Fragmentation 
As magmas rise, volatiles may begin to exsolve. The solubility of water (n), the major volatile 
species in basalt, is approximated by Equation 1 (Jaupart and Tait 1990, p. 219). The depth at

ANL-MGR-GS-000002, Rev 00 35 April 2000 
which exsolution of water vapor begins to occur is the depth at which the magma becomes 
saturated with respect to its original water content, which, assuming lithostatic pressure (P = 
.cgd, where d is depth; see Section 5, Assumption 5), can be derived as: 
d 
n 
g exs 
i 
c 
= 
× ( )- / . / 6 8 10 8 10 7 
. 
(Eq. 4) 
where dexs is exsolution depth in meters (m), ni is the initial dissolved mass fraction of water at 
the magma’s depth of origin, .c is the average density of the crust above dexs in kg/m3, and g is 
gravitational acceleration (m/s2). This relation is plotted in Figure 1. The mass fraction of water 
exsolved from a basaltic magma, nexs, at a given depth is 
nexs = ni – n when d < dexs (Eq. 5a) 
nexs = 0 when d > dexs . (Eq. 5b) 
The density of the mixture of silicate melt and water vapor bubbles ( .mix) can be calculated from 
(Wilson and Head 1981, p. 2973) 
1 1 
. . . mix 
exs 
g 
exs 
m 
n n = + - ( ) 
. (Eq. 6) 
The density of the gas phase ( .g) can be calculated using the ideal gas law, 
.g 
P 
RT 
= (Eq. 7) 
where R is the gas constant for water (in this report, a value of 461 J/kg-K is used) and T is 
temperature. If it is assumed that the pressure in a conduit or dike is determined by the 
lithostatic pressure, .g can be computed as a function of depth d: 
. . 
g 
cgd 
RT 
= . (Eq. 8)

ANL-MGR-GS-000002, Rev 00 36 April 2000 
DTN: N/A (plot of Equation 4) 
NOTE: The calculations assume that pressure in the magma column is lithostatic and that bubble nucleation 
kinetics can be ignored. The average (shallow) crustal density ( .c) is taken to be 2000 kg/m3, as an 
example. 
Figure 1. Plot of the Depth at Which Volatile (H2O) Exsolution Begins 
(dexs) for Initial Dissolved Water Content (ni) up to 0.05 
Equations 1 and 4 to 8 can be used to calculate the mixture density for any initial volatile content 
at any depth, which may be useful for estimating the interactions between the mixture and the 
repository. The mixture density can also be expressed in terms of gas volume fraction, f, as 
0
1
2
3
4
5
6
7
8
9 
10 
11 
12 
13
0 0.01 0.02 0.03 0.04 0.05 
ni 
dexs (km)

ANL-MGR-GS-000002, Rev 00 37 April 2000 
. f. f. mix g m = + - ( ) 1 (Eq. 9) 
Rearranging, the gas volume fraction is here derived as: 
f . . 
. . 
= - 
- 
mix m 
g m 
(Eq. 10) 
Figure 2 shows the depth at which fragmentation occurs in rising basalt, assuming that: 
1. The flow is steady and homogeneous, the system is closed (no gas loss into country 
rock), and bubble nucleation and growth kinetics can be ignored (see Section 5, 
Assumption 6). 
2. The vertical pressure profile in the dike/conduit below the fragmentation depth is very 
close to the lithostatic pressure profile (see Section 5, Assumption 5). 
3. A gas volume fraction at which fragmentation commences can be established. 
The limitations of the first assumption have already been discussed. The second assumption is 
very good at depths where f is small, but it becomes less accurate toward the fragmentation 
depth, and it is probably very inaccurate above the fragmentation depth. However, the second 
assumption is a good estimate of the “average” fragmentation depth for a variety of different 
scenarios. The third assumption is currently a subject of intense research. A critical value of f 
at which fragmentation occurs has commonly been assumed to be close to 0.75 (Mader 1998, p. 
55), and this is adopted in Figure 2. Recent studies have demonstrated, however, that 
fragmentation can take place in a range from 0.60 < f < 0.95 (for example, Mader 1998, p. 56). 
The commonly assumed critical fragmentation value of fcrit= 0.75 is adopted as a reasonable 
estimate given how little is understood about this process, particularly with regard to basaltic 
magmas (see Section 5, Assumption 7). With all these assumptions, Figure 2 illustrates that 
estimated fragmentation depths for initial volatile contents between 0 and 4 wt% ranges from 
about 0 to 900 m.

ANL-MGR-GS-000002, Rev 00 38 April 2000 
DTN: N/A (plot of Equation 10) 
NOTE: Calculations assume .c= 2000 kg/m3, .m = 3000 kg/m3, T = 1300 K, and R = 461 J kg/K. The dashed line 
defines a critical gas volume fraction of 0.75, which in this report is assumed to be the threshold for 
fragmentation of the magma. Plot is derived by solving Equations 1 and 5 as functions of depth for a given 
value of ni, Equations 8 and 6, and finally Equation 10 for each value of ni. 
Figure 2. Plot of the Variation of Gas Volume Fraction ( f) with Depth (d), Assuming Pressure in the 
Magma is Lithostatic, for Initial Dissolved Water Content ni = 0.01, 0.02, 0.03, 0.04, and 0.05. 
0
1
2
3
4
5
6
7
8
9 
10 
11 
12
0 0.2 0.4 0.6 0.8 1.0 
f 
d (km) 
Fragmented flow 
ni = 0.05 
0.01 
0.02 
0.03 
0.04

ANL-MGR-GS-000002, Rev 00 39 April 2000 
6.3.3 Velocity as a Function of Depth Above dexs 
Descriptions of the magma velocity, conduit/dike dimensions, and magma pressure as functions 
of d require, even with the homogeneous flow approximation and a steady-state assumption, 
solution of three coupled equations (Wilson and Head 1981, Equations 16, 17, and 18 on p. 
2974). Two of these equations are ordinary differential equations. Detailed solution of these 
equations for a range of parameters appropriate to volcanism in the YMR is beyond the scope of 
this report. However, Wilson and Head (1981, p. 2983) do provide some plots that relate 
eruption velocity, uerupt, (where the magma-gas mixture exits the vent) to initial dissolved water 
content (ni) of the magma, assuming that the pressure in the conduit/dike is equal to lithostatic 
pressure. Their solutions, shown with the solid curves in Figures 3 and 4, are for values of ni up 
to approximately 0.02 for both dike (fissure) and circular conduit geometries. As discussed in 
Section 6.2.2, it is possible that ni values for basalts of the YMR have been as high as 0.03 to 
0.04, and the possibility of values as high as 0.05 is allowed in these plots. It is expected that 
YMR basaltic magmas with such high water contents would not erupt (Section 6.2.2). Thus, 
Figures 3 and 4 show the extrapolated values (dashed parts of the curves) for velocity at these 
higher initial water contents. Note that these are only graphical extrapolations, not actual 
solutions to the governing equations. However, given the various simplifications that are made 
in arriving at the Wilson and Head (1981, p. 2983) results, these extrapolations are reasonable 
approximations (see Section 5, Assumption 9). 
The velocity of magma ascending from some depth to the vent probably can be estimated with 
sufficient accuracy for PA by simplifying such that velocity increases linearly from 0.01uerupt at 
dexs to 0.1uerupt at the fragmentation depth, thence increasing linearly to uerupt at the vent (uerupt 
obtained from Figures 3 and 4). Using such an approach will account for the greater 
accelerations that are thought to occur above the fragmentation depth and the more gradual 
acceleration below it. In addition, this approach guarantees consistency in the calculations of 
velocity at various depths (as opposed to random sampling from distributions at different 
depths). 
6.3.4 Eruption Duration and Volume 
Eruption duration is difficult to estimate because, during the formation of a volcanic center, it is 
likely that eruptive discharge rates could have varied substantially. Wood (1980, p. 402) 
provides data on the duration of scoria-cone forming eruptions, showing that they range from 
one day to about 15 years, with a median value of 30 days. Wood (1980, p. 402) also states that 
about 93% of such eruptions last less than one year. Note that this duration is for formation of 
the entire volcano, including lava flows, scoria cone, and fallout blanket. As mentioned above, 
the aa character of the Lathrop Wells lava flows implies a mass discharge rate of at least 3 x 104 
kg/s. Using this value as a conservative minimum eruption rate, the Lathrop Wells volcano, with 
a total volume of about 108 m3 (Crowe et al. 1983, p. 269; mass of about 3 x 1011 kg calculated 
using an approximated magma density of 2600 kg/m3 from Table 4), would have erupted in 
about 107 s (about 120 days) if the eruption rate was maintained during that time. For 
comparison, the Hekla 1947 eruption reached discharge rates of about 4.7 x 107 kg/s during 
highly explosive phases (Table 5). At this rate, which could be considered a reasonable

ANL-MGR-GS-000002, Rev 00 40 April 2000 
Source: Wilson and Head (1981); plot of equations from reference and extrapolations 
NOTE: Solid curves show values calculated by Wilson and Head (1981, p. 2983), whereas dashed lines are 
graphical extrapolations to include the range of initial volatile contents of concern for Yucca Mountain. The 
Wilson and Head calculations assume homogeneous flow and lithostatic pressure in the rising magma 
column. 
Figure 3. Plot of the Variation of Eruption Velocity (uerupt) with Initial Dissolved Water 
Content (ni) for Various Mass Discharge Rates Along a Fissure 
maximum rate for volcanoes of the YMR, the Lathrop Wells volcano would have completely 
formed in about 1.8 hours, which is an unrealistically short time. For total eruption duration 
(formation of the entire volcano), a log normal distribution with a minimum of one day, a mean 
of 30 days, and a maximum of 15 years is recommended. 
Total erupted volume can be obtained by multiplying eruption duration by mass discharge rate, 
and then dividing by magma density of 2600 kg/m3 (a representative density for magmas for a 
Lathrop Wells type eruption, see Table 4). This will result in a “dense rock equivalent” volume 
(often referred to as the DRE volume). The bulk volume of deposits from an eruption will be 
larger because of the presence of voids (vesicles) within particles and of void space between 
particles. For a violent strombolian eruption, the fallout blanket will have a density within a 
range specified below. If the bulk volume of a violent strombolian eruption is needed, then one 
should use the bulk density (see Section 6.5.3) instead of the magma density. 
0.05 
0.04 
0.03 
0.02 
0.01 
0.007 
0.005 
0.003 
0.002 
25 50 100 200 300 400 500 
Calculated by Wilson 
and Head (1981) 
Extrapolated 
Fissure eruption 
Eruption velocity (m/s) 
Initial dissolved H2O content (mass fraction) 
103 kgs-1m-1 
104 kgs-1m-1 
105 kgs-1m-1 
106 kgs-1m-1

ANL-MGR-GS-000002, Rev 00 41 April 2000 
Source: Wilson and Head (1981); plot of equations 17 to 18 from reference and extrapolations 
NOTE: Solid curves show values calculated by Wilson and Head (1981, p. 2983), whereas dashed lines are 
graphical extrapolations to include the range of initial volatile contents of concern for Yucca Mountain. The 
Wilson and Head calculations are based on the assumption of homogeneous flow and lithostatic pressure in 
the rising magma column. 
Figure 4. Plot of the Variation of Eruption Velocity (uerupt) with Initial Dissolved Water (ni) 
Content for Various Mass Discharge Rates from a Circular Conduit. 
Table 5. Explosive Eruptive Events, Duration, and Power and Estimated Mass Discharge Rates 
Used to Develop Probability Distributions for Eruptive Plume Dispersal Calculations 
Event Log (t) 
(t in s) a 
Log (Po) 
(Po in W) a 
Mass Discharge Rate 
(kg/s) b 
Cerro Negro, 1992 
Hekla, 1970 
Tolbachik, 1975 
Paricutin, 1944 I 
Paricutin, 1944 II 
Paricutin, 1946 
Hekla, 1947 
Heimaey, 1973 
4.8 
3.9 
6.1 
5.6 
6.8 
6.8 
3.3 
6.4 
12.0 
12.8 
11.7 
11.1 
11.5 
9.0 
13.8 
9.9 
7.4 x 105 
4.7 x 106 
3.7 x 105 
9.3 x 104 
2.3 x 105 
7.4 x 102 
4.7 x 107 
5.9 x 103 
Sources: aJarzemba (1997, p. 136) 
b Mass discharge rates based on T = 1350 K and magma heat capacity cp = 1000 J/kg-K (Best 1982, 
p. 301). Mass discharge rate = Po(cpT)-1. 
0.05 
0.04 
0.03 
0.02 
0.01 
0.007 
0.005 
0.003 
0.002 
25 50 100 200 300 400 500 
Calculated by Wilson 
and Head (1981) 
Extrapolated 
Central vent (conduit) eruption 
Eruption velocity (m/s) 
Initial dissolved H2O content (mass fraction) 
104 kg/s 
106 kg/s 
108 kg/s 
109 kg/s

ANL-MGR-GS-000002, Rev 00 42 April 2000 
For the duration of individual explosive phases that produce a high column and disperse ash 
widely, we adopt the same range of parameter values used in Jarzemba (1997, pp. 136–137; see 
Section 5, Assumption 8). The data supporting this range are shown in Table 5, which also 
includes the estimated mass discharge rate for the eruptions, using an estimated magma specific 
heat of 1000 J/kg-K (see, for example, the range of values in Best 1982, p. 301) and temperature 
of 1350 K. Explosive phases lasted from about half an hour to 73 days. However, we note that 
the longer duration events occurred at volcanoes of larger volume than is typical of the YMR in 
the Quaternary. For example, Paricutin volcano is more than an order of magnitude larger in 
volume (2.1 x 109 m3; Wood 1980, p. 390) than the Lathrop Wells volcano. 
6.4 ENTRAINMENT OF RADIOACTIVE WASTE IN ASCENDING MAGMA 
Quantification of the amount of waste that could be entrained by rising magma and subsequently 
erupted and dispersed is difficult because of uncertainties regarding the potential interactions of 
the magmatic system with the repository. Some of these uncertainties are volcanological in 
nature, and some are related to the nature of the engineered system; the latter are beyond the 
scope of this report. 
Uncertainties are inherent in the following volcanic processes: (1) the interaction between a 
rising dike and the perturbed stress field around repository drifts; (2) the interaction between 
rising, vesiculating magma and the partially open drifts (for example, would magma run like lava 
flows for long distances down the drifts, would it pile up quickly to block the drift and therefore 
allow magma to continue rising, or would it explode down the drift?); and (3) the depth to which 
conduits might extend (that is, if a wide conduit is formed but extends only 200 m below the 
surface, then it will not have as large a disruptive effect on the potential repository). 
There are a few data available on the interaction of magma with undisturbed country rock and 
subsequent eruption of the lithic debris for the range of eruptive styles that can be reasonably 
expected at Yucca Mountain. For example, Valentine and Groves (1996, pp. 79–84) report data 
on the quantity of wall rock debris erupted from various depths during strombolian, Hawaiian, 
effusive, and hydrovolcanic activity at two volcanoes. Hydrovolcanic eruptions reported by 
Valentine and Groves contained between 0.32 and 0.91 volume fraction of wall rock debris, with 
most of that originating in the uppermost ~510 m of the dike/conduit feeder systems. 
Strombolian, Hawaiian, and effusive eruptions ejected much lower volumes of wall rock debris, 
commonly resulting in total volume fractions of 10–3 to 10–5. Studies of more sites, including 
those that probably produced violent strombolian eruptions, were not completed by YMP. 
Doubik and Hill (1999, p. 60) state that the Lathrop Wells volcano has a relatively high average 
lithic volume fraction of 9 x 10–3 for xenoliths > 1 mm, based on image analysis of unspecified 
locations. It is possible that all the locations studied by Doubik and Hill were located in a quarry 
that exposes proximal cone deposits. Clarification of this issue will require analysis of more 
exposures at Lathrop Wells and analysis of previously collected data. Addressing this issue may 
be important because Doubik and Hill (1999) cite similarity of lithic content as a justification for 
using the relatively large and violent Tolbachik eruptions as analogs for the Lathrop Wells 
volcano (and, hence, potential eruptions at Yucca Mountain).

ANL-MGR-GS-000002, Rev 00 43 April 2000 
6.5 ASH PLUMES AND THEIR DEPOSITS 
6.5.1 Bulk Particle Size and Distribution of Deposits from Strombolian and Violent 
Strombolian Eruptions 
As described in Section 6.3, explosive eruptive styles of Quaternary volcanoes in the YMR 
include both strombolian and violent strombolian. Strombolian eruptions are characterized by 
short-duration bursts that throw relatively coarse fragments of melt out on ballistic trajectories. 
Most of the fragments (clasts) are deposited immediately around the vent, with only a very small 
fraction of finer particles rising higher and being dispersed by wind to form minor fallout sheets. 
Table 6 shows estimated bulk eruptive grain-size distribution parameters for the Etna Northeast 
Crater eruptions of September 1971 (McGetchin et al. 1974, Figure 8, p. 3264). This result is 
probably representative of many strombolian eruptions, being skewed toward very coarse clast 
sizes. 
Violent strombolian eruptions, on the other hand, are characterized by vertical eruption of a highspeed 
jet of a gas-clast mixture. As the eruptive mixture rises in the jet, it entrains and heats air, 
which in turn reduces the bulk mixture density until the jet becomes buoyant and continues to 
rise as a plume. The plume rises to an altitude of neutral buoyancy compared to the surrounding 
atmosphere, in which it then spreads laterally as an anvil or “umbrella” cloud that is transported 
downwind. Clasts fall out from both the vertical eruption column and from the umbrella cloud 
according to their settling velocities. Such an eruption tends to produce a fallout sheet with 
volume comparable to or as much as 13 times that of the cone (excluding lava flows; Crowe et 
al. 1983, p. 272). Historic violent strombolian eruptions at Paricutin produced a fallout 
sheet:cone volume ratio of about 4:1, and Sunset Crater (Arizona) produced a ratio of about 3.2:1 
(Crowe et al. 1983, p. 272). Table 6 shows bulk eruptive grain-size distributions for three violent 
strombolian eruptions (Tolbachik and Cerro Negro, 1971 and 1968; Maleyev and Vande-Kirkov 
1983, pp. 61–62; Rose et al. 1973, p. 342; see Section 5, Assumption 8). Mean clast diameters 
for these eruptions range from 0.19 to 0.37 mm, and standard deviations range from 1.5 to 
2.5 F units ( F = –log2d, where d is the particle diameter in mm). For comparison, Jarzemba 
(1997, p. 137) gives a log-triangular distribution with a minimum of 0.1 mm, a maximum of 100 
mm, and a median of 1 mm. 
Given the data in Table 6, and the fact that there are not many data available to constrain bulk 
particle size in violent strombolian eruptions, we suggest using a log triangular distribution for 
mean clast size, as Jarzemba (1997, p. 137) did, but have the minimum value be 0.01 mm, the 
mode at 0.1 mm, and the maximum value be 1.0 mm. This distribution more closely matches the 
data provided here. 
Given a mean clast size, the standard deviation of the particle size is needed to provide 
ASHPLUME with sufficient information on the particle size distribution. Table 6 provides 
information on the graphic standard deviation sF, which is defined as 
sF = ( F84 - F16)/2 (Eq. 11)

ANL-MGR-GS-000002, Rev 00 44 April 2000 
where F84 is the 84th percentile grain size and F16 is the 16th percentile grain size expressed in f 
units. It is recommended that, for a given mean particle diameter, sF be sampled from a uniform 
distribution between sF = 1 and sF = 3. 
Table 6. Estimated Bulk Clast Size Distribution Parameters for Three Violent Strombolian 
Eruptions (Tolbachik and Cerro Negro 1971 and 1968) and One Strombolian Eruption (Etna 1971) 
Combined Great 
Tolbachik N. 
Breakthrougha 
Cerro Negro 1971 
(overall)b 
Cerro Negro 1968 
(overall)b 
Bulk Etna 
Northeast Craterc 
Median (mm) 0.3 0.24 0.15 95 
Graphic Mean 
(mm) 
0.37 0.23 0.19 110 
Graphic Standard 
Deviation (sF) 
2.5 1.5 1.83 3.48 
Sources: a Derived from data presented in Maleyev and Vande-Kirkov (1983, pp. 61–62). 
b Rose et al. (1973, p. 342). 
c McGetchin et al. (1974, p. 3264). 
6.5.2 Clast Characteristics 
The clasts produced by strombolian and violent strombolian eruptions can be quite different in 
character. As can be seen in Table 6, strombolian eruptions produce a much higher proportion of 
coarse clasts, with the mean size commonly being > 10 cm. Common strombolian clast types 
include ribbon, spindle, and cowpie bombs. Ribbon and spindle bombs take their shape as they 
are stretched and torn or as they spin through the air on their dominantly ballistic paths; these 
shapes indicate the hot, fluid state of the clasts during flight. Cowpie bombs are very hot and 
fluid when they hit the ground. All these clasts are hot during flight and deposition because of 
their large size (low surface-area-to-volume ratio minimizes heat loss) and low eruption height 
(they have less time to cool before hitting the ground). These large clasts may have vesicle 
(bubble) volume fractions up to ~70%. Smaller clasts, in the mm to cm range, tend to be subequant 
vesicular scoria clasts, and they can have a range of vesicularities (for example, the 
Cinder Cone eruption at Lassen Volcanic National Park, California, produced scoria with 
vesicularities of 20 to 70%; Heiken and Wohletz 1985, p. 34). Finer ash-sized clasts tend to be 
less vesicular, and can range from irregular to fluidal to blocky in shape. 
Violent strombolian eruptions carry clasts much higher in the air, providing more cooling time; 
the clasts cool more quickly because they have a much higher degree of fragmentation. A much 
larger proportion of the clasts is in the mm to cm size range compared to strombolian eruptions, 
and most of these clasts have irregular shapes and relatively high vesicularities. 
In violent strombolian eruptions, the long-range, downwind transport and fallout of clasts 
becomes an important issue for YMP PA calculations. Transport and deposition of clasts depend 
on their settling velocity in air, which in turn depends on their bulk density (the melt density 
corrected for the porosity, or vesicularity, of the clasts) and shape. Calculations of clast dispersal

ANL-MGR-GS-000002, Rev 00 45 April 2000 
commonly use a shape factor, F = (b + c)/2a, where a, b, and c are the lengths of the longest, 
medium, and shortest axes of the clasts. Clasts produced by these types of eruptions can have a 
range of shapes. Jarzemba (1997, p. 139) used a value of F = 0.5 as a shape factor that is likely 
to be representative of common clast shapes, and in the absence of further data, we recommend 
this value for PA calculations for YMP. 
Density of erupted particles varies with particle size because larger particles tend to have a 
higher fraction of vesicles (bubble voids) than small particles. Detailed data are lacking, but it is 
recommended that the particle density be varied as follows: 
• For particle diameters less than or equal to 0.01 mm, the particle density is 0.8 of the 
magma density (which is taken to have an average value of 2600 kg/m3 for a Lathrop 
Wells-type magma). This is based on a fine-particles void fraction of 0.2 due to vesicles. 
• For particle diameters greater than or equal to 10 mm, the particle density is 0.4 of the 
magma density. This is based on a void fraction of 0.6 due to vesicles. 
• Between 0.01 mm and 10 mm, density should decrease linearly with increasing diameter. 
6.5.3 Density of Fallout Deposits 
Bulk in-situ density of fallout deposits typically ranges from 300 to 1500 kg/m3 (Sparks et al. 
1997, p. 366) but is rarely directly measured, particularly for basaltic deposits such as are most 
likely in the YMR. Blong (1984, p. 208) estimates that some fallout deposits have a density of 
approximately 1000 kg/m3. There are two possible ways of treating deposit density in TSPA-SR 
calculations: (1) simply use 1000 kg/m3 or (2) sample from a normal distribution of deposit 
densities ranging from 300 to 1500 kg/m3, with a mean of 1000 kg/m3 (see Section 5, 
Assumption 9).

ANL-MGR-GS-000002, Rev 00 46 April 2000 
INTENTIONALLY LEFT BLANK

ANL-MGR-GS-000002, Rev 00 47 April 2000 
7. CONCLUSIONS 
This AMR provides technical bases for parameters that will be used by PA related to the effects 
of a volcanic eruption through the potential Yucca Mountain repository. Uncertainties in the 
parameters are described in the text as appropriate. The information in this AMR is based 
largely on literature values and simple calculations. 
The following specific parameter distributions are suggested: 
• Conduit diameter – Log normal distribution, minimum diameter equal to dike width, 
median diameter equal to 50 m, maximum value 150 m. 
• Dike width – Log normal distribution, minimum of 0.5 m, mean of 1.5 m, 95th percentile 
value of 4.5 m. 
• Number of dikes associated with formation of a new volcano – Log normal distribution 
with minimum of 1, mean of 3, 95th percentile value of 10. 
• Magma chemistry – Mean Lathrop Wells composition, Table 2. 
• Water content of magmas – Uniform distribution between 1 and 3 wt%, zero probability 
of 0 wt% increasing linearly to 1 wt%, zero probability of 4 wt% with linear distribution 
between 3 and 4 wt%. 
• Gas composition – Derived from a suite of active volcanoes, Table 3. 
• Magmatic temperatures, viscosities, and densities – Calculated from theoretical relations, 
Table 4. Liquidus temperature ranges from 1046 to 1169oC, viscosity ranges from 1.957 
to 2.678 (log poise units), density ranges from 2474 to 2663 kg/m3. 
• Magma ascent rate below vesiculation depth – Equation 3. 
• Volatile exsolution depths – Figure 1, range from about 9 km to zero depth for water 
contents between 0 and 4 wt%. 
• Fragmentation depths – Figure 2, range from 0 to 900 m (approximately) for water 
contents between 0 and 4 wt%. 
• Velocity as a function of depth –Eruption velocity uerupt is estimated from Figures 3 and 
4. Velocity then decreases linearly downward to 0.1uerupt at the fragmentation depth. 
Below fragmentation depth the velocity continues to decrease linearly to 0.01uerupt at the 
depth where water exsolution begins. 
• Eruption duration – For formation of an entire volcano, a log normal distribution with a 
minimum of one day, a mean of 30 days, and a maximum of 15 years. Duration and 
volume of individual explosive phases during formation of a new volcano should be a 
probability distribution function derived from Table 5, with a cutoff so that sampled

ANL-MGR-GS-000002, Rev 00 48 April 2000 
volumes or the sums of sampled volumes do not exceed the sampled volume of the whole 
volcano. 
• Mean particle size erupted during violent strombolian phases – Log triangular 
distribution with a minimum of 0.01 mm, a mode of 0.1 mm, and a maximum of 1.0 mm. 
• Standard deviation of particle size distribution for a given mean – Uniform distribution 
between sf = 1 and sf = 3. 
• Clast characteristics – Shape factor of 0.5. 
• Density of erupted particles – For particle diameters less than or equal to 0.01 mm, 
density is 0.8 of the magma density. For particles greater than 10 mm, density is 0.4 of 
the magma density. For particles between 0.01 and 10 mm, density should decrease 
linearly with increasing diameter. 
• There are two possible ways of treating deposit density in TSPA-SR calculations – (1) 
Simply use 1000 kg/m3 or (2) sample from a normal distribution of deposit densities 
ranging from 300 to 1500 kg/m3, with a mean of 1000 kg/m3. 
The current qualification status of input data on major element composition of the Lathrop Wells 
volcanic center is qualified.

ANL-MGR-GS-000002, Rev 00 49 April 2000 
8. INPUTS AND REFERENCES 
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000003. Las Vegas, Nevada: CRWMS M&O. ACC:MOL.19990811.0287 
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Rose, W.I., Jr., Bonis, S., Stoiber, R.E., Keller, M., and Bickford, T. 1973. “Studies of Volcanic 
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Controls the Lava Structure.” Bulletin of Volcanology, 52, 615–628. New York, New York: 
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A.W. 1997. Volcanic Plumes. New York, New York: John Wiley & Sons, 574 pp. TIC: 
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Valentine, G.A., and Groves, K.R. 1996. “Entrainment of Country Rock During Basaltic 
Eruptions of the Lucero Volcanic Field, New Mexico.” Journal of Geology, 104, 71–90. 
Chicago, Illinois: University of Chicago Press. TIC: 246146. 
Vergniolle, S., and Jaupart, C. 1986. “Separated Two-Phase Flow and Basaltic Eruptions.” 
Journal of Geophysical Research, 91, (B12), 12842–12860. Washington, D.C.: American 
Geophysical Union. TIC: 239308. 
Wemheuer, R.F. 1999. “First Issue of FY00 NEPO QAP-2-0 Activity Evaluations.” Interoffice 
correspondence from R.F. Wemheuer (CRWMS M&O) to R.A. Morgan (CRWMS M&O), 
October 1, 1999, LV.NEPO.RTPS.TAG.10/99-155, with attachments, Activity Evaluations. 
ACC: MOL.19991028.0162.

ANL-MGR-GS-000002, Rev 00 53 April 2000 
Wilson, L., and Head, J.W., III. 1981. “Ascent and Eruption of Basaltic Magma on the Earth 
and Moon.” Journal of Geophysical Research, 86, (B4), 2971–3001. Washington, D.C.: 
American Geophysical Union. TIC: 225185. 
WoldeGabriel, G., Keating, G.N., and Valentine, G.A. 1999. “Effects of Shallow Basaltic 
Intrusion into Pyroclastic Deposits, Grants Ridge, New Mexico, USA.” Journal of Volcanology 
and Geothermal Research, 92, 389–411. Amsterdam, The Netherlands: Elsevier Science. TIC: 
246037. 
Wood, C.A. 1980. “Morphometric Evolution of Cinder Cones.” Journal of Volcanology and 
Geothermal Research, 7, 387–413. Amsterdam, The Netherlands: Elsevier Scientific Publishing. 
TIC: 225565. 
Yoder, H.S., Jr., and Tilley, C.E. 1962. “Origin of Basalt Magmas: An Experimental Study of 
Natural and Synthetic Rock Systems.” Journal of Petrology, 3, (3), 342–532. London, England: 
Oxford University Press. TIC: 247024. 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
AP-3.10Q, Rev 2, ICN 0. Analyses and Models. Washington, D.C.: U.S. Department of Energy, 
Office of Civilian Radioactive Waste Management. ACC: MOL.200000217.0246. 
DOE. 2000. Quality Assurance Requirements and Description. DOE/RW-0333P, Rev. 9. 
Washington, D.C.: DOE OCRWM. ACC: MOL.199910281.0012. 
QAP-2-0, Rev. 5. Conduct of Activities. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.19980826.0209. 
QAP-2-3, Rev. 10. Classification of Permanent Items. Las Vegas, Nevada, CRWMS M&O. 
ACC: MOL.19990316.0006. 
8.3 SOURCE DATA, LISTED BY DATA TRACKING NUMBERS 
LA000000000099.002. Major Element, Trace Element, Isotopic, and Mineral Chemistry Data 
from Lathrop Wells. Submittal date: 08/02/1995. 
LAGV831812AQ97.001. Magmatic Effect Data for Revision and Final Publication of the 
Volcanism Synthesis Report. Submittal date: 08/29/1997.