Caplan, A.J., Duennebier, F., and Okubo, P., 1997, Seismicity of the 1996 Loihi Seamount eruption [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p. 7. [Geological Society of America, 93rd Annual Cordilleran Section meeting, Kailua-Kona, HI, May 21-23, 1997]

The earthquake swarm which began on July 16, 1996 on Loihi seamount was the largest ever recorded on a Hawaiian volcano. The initial phase of activity, lasting for three days and consisting of 72 located events, was followed by 30 hours of quiescence. The main body of the swarm began on July 20, averaging over 88 events per day for the next ten days and over 12 events per day for the subsequent 12 days. Hypocentral locations were calculated for over 1200 events using data from the seismic network operated by the Hawaii Volcano Observatory (HVO). Initial hypocentral locations suggested a sharply delineated plane of seismicity between 13 and 14 km depth, shallowing to the south. The HVO network lies north of Loihi seamount, and there are no permanent seismometers located elsewhere near Loihi, hence these initial locations were found to be imprecise. Data from an ocean bottom seismometer (OBS), enabled us to approximate a new velocity model for the area beneath Loihi seamount. The new velocity model allows us to relocate swarm events with tighter constraints on earthquake location. The majority of events cluster near the summit of the volcano. Those events for which we have both HVO and OBS data lie at depths of approximately 8-9 km. These depths are consistent with petrologic data which suggest the presence of a Loihi magma chamber near depths of 9-10 km. Due to locator bias, depths on events for which we have no OBS data are poorly constrained.

Cashman, K.V., and Kauahikaua, J.P., 1997, Reevaluation of vesicle distributions in basaltic lava flows: Geology, v. 25, no. 5, p. 419-422.

A fundamental dichotomy in the study of basaltic lava flows is that observations of active flows are restricted to flow surfaces, yet older flows are often exposed only in vertical cross section. Cross-sectional exposures of an inflated basaltic sheet flow emplaced in Kalapana, Hawaii, from 1990 to 1991 provide an unusual opportunity to merge these two viewpoints, permitting the development of the internal structure of the flow to be viewed in the context of its known emplacement history. We demonstrate that fundamental features of the flow structure-a thick upper vesicular crust that diminishes downward in overall vesicularity, a dense flow interior, and a thin lower vesicular zone-are generated through syn-emplacement cooling of upper and lower flow crusts. Both the inverse correlation of overall vesicularity and vesicle size and the constant relative thickness of the upper vesicular zone are unique to inflated flows and permit a reinterpretation of flows previously interpreted to be ponded (rapidly emplaced). Identification of inflation, in turn, implies near-horizontal paleoslopes and permits estimates of flow duration based on upper flow crust thickness.

Cashman, K.V., Kauahikaua, J.P., and Thornber, C., 1997, Cooling and crystallization in open lava channels [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F793. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

We have measured rates of lava cooling and crystallization within a lava channel active at Kilauea Volcano in May, 1997. Samples were collected from both the channel and channel breakouts over a distance of 1 to 2.3 km from the feeder vent. Over this distance, channel lava changed from pahoehoe to 'a'a in surface texture, and channel breakouts changed from smooth to pasty (transitional) pahoehoe. Examination of sample thin sections shows that (1) while vent samples contain only minor phenocrystic olivine, all channel samples that we examined contained microlites of plagioclase and pyroxene; (2) open channel and breakout samples collected at similar distance from the vent have similar groundmass crystallinities; and (3) pahoehoe breakouts from the 'a'a portion of the channel have lower crystallinities than corresponding channel surface samples. Measured glass compositions indicate cooling of channel core lava of almost 20° over 2.3 km (30°C/hr) and corresponding increases in groundmass crystallinity of 20%. These temperature and crystallinity changes can be adequately modeled using observed flow velocities and thicknesses and assuming radiative cooling under conditions of perfect mixing (e.g., Crisp and Baloga, 1994). This suggests that cooling in proximal 'a'a channels is controlled by wholesale mixing of the flow, consistent with observations of unsteady flow behavior in the early stages of channel formation. Furthermore, this mixing and protracted radiative cooling induces rapid crystallization throughout the flow thickness, thus explaining the consistently fine-grained textures within and among Hawaiian 'a'a flows.

Chouet, B., Dawson, P., Ohminato, T., and Okubo, P., 1997, Broadband measurements of magmatic injection beneath Kilauea volcano, Hawaii [abs.]: Seismological Research Letters, v. 68, no. 2, p. 317. [Seismological Society of America, 92nd Annual Meeting, Honolulu, HI, April 9-11, 1997]

We use data from short-period and broadband seismometers deployed around the summit of Kilauea Volcano, and electronic tilt measurements made in the summit vault to quantify the mechanism associated with a transient in the flow of magma feeding the east rift eruption of the volcano. The transient has a duration of 24 h and is marked by rapid inflation of the Kilauea summit peaking at 15 microradians 4 h into the event. A swarm of volcano-tectonic (VT) earthquakes superimposed on tremor with periods of 0.3-1 s is observed starting within a half hour of the onset of detectable tilt. Accompanying the short-period seismicity are a series of pulses with periods near 30 s occurring at intervals of 2-3 min, which lead into an episode of sustained tremor with periods near 15 s 1.5 h after the onset of inflation. Peak tremor and VT activities occur between 2 and 3 h after the beginning of inflation and decay rapidly to background levels within the next 2 h. Particle trajectories associated with the pulses are linear and dominated by compressional motion at all receiver sites. The similarities of the waveforms point to the repeated activation of a fixed source. The source location inferred from semblance and particle motion analyses is 1 km beneath the northeastern edge of the Halemaumau pit crater. The radiation pattern of the pulses and moment tensor inversions of the data are consistent with a pulsating transport mechanism operating on an inclined fracture linking the summit reservoir to the east rift of Kilauea. The VT earthquakes are thought to represent the brittle response of the shallow crust to this forceful injection, and the shorter-period tremor is viewed as a manifestation of mechanisms of vesiculation and degassing in the magma.

Conrey, R.M., Sherrod, D.R., Hooper, P.R., and Swanson, D.A., 1997, Diverse primitive magmas in the Cascade arc, northern Oregon and southern Washington: Canadian Mineralogist, v. 35, p. 367-396.

Bulk-rock and major- and trace-element composition, petrography and mineral compositions are presented for a diverse suite of 22 primitive mafic lavas in the Cascade Range of northern Oregon and southern Washington. With the exception of an early Western Cascade basalt, all the rocks are younger than 7 Ma. Intensive parameters [ò(H2O), ò(O2), T, P] for the magmas have been inferred mostly from equilibrium olivine-liquid and plagioclase-liquid relations. Nearly anhydrous, MORB-like, low-K tholeiite was probably derived from relatively high degrees of decompression-induced melting of shallow, depleted, relatively unmetasomatized lithospheric mantle during intra-arc rifting. The degree of partial melting decreases northward along the arc, whereas the depth of average melt generation increases. OIB-like basalt represents deeper, wetter, smaller-degree melts of more enriched asthenospheric mantle, unaffected by subduction. Olivine analcimite resembles the silicate melt considered responsible for within-plate mantle metasomatism. Post-7-Ma subduction-related basalt was derived by low degrees of partial melting of subduction-metasomatized garnet lherzolite, similar to OIB-like basalt source-mantle before modification. The spectrum of subduction-related basalt from cooler and wetter (and slightly more oxidized) absarokite to pregressively hotter and drier high-K calc-alkaline basalt and calc-alkaline basalt seems to be due to varying degrees of metasomatism of the deep mantle wedge by relatively cool, wet, LILE-rich absarokitic magmas coming from near the subducted slab. Early Western Cascade basalt is more typically arc-like in its composition and mineralogy, and was probably generated under H2O-rich conditions when more vigorous subduction prevailed. Depleted basaltic andesite may have been generated by low degrees of partial melting of residual harzburgite, possibly formed during the generation of early Western Cascade basalt.

Elias, T., and Sutton, A.J., 1997, SO2 Emission rate measurements at Kilauea Volcano, Hawaii [abs.], in IAVCEI, 6th Field Workshop on Volcanic Gases, Hawaii National Park, HI, May 1997, Abstracts: Hawaii National Park, HI, U.S. Geological Survey, University of Hawaii at Hilo, Center for the Study of Active Volcanoes, [unpag.]. [Sponsored by International Association of Volcanology and Chemistry of the Earth's Interior]

Kilauea volcano, currently in its 15th year of nearly continuous eruptive activity, releases significant amounts of SO2 from its summit and middle East Rift Zone (ERZ). Summit SO 2 emission rates have been regularly measured at Kilauea using a Correlation Spectrometer (COSPEC) since 1982. This ongoing record shows that variations in SO2 emission rate reflect changes in eruptive activity. Recently, a waning in the eruptive activity on the ERZ was accompanied by a decline in summit emissions, and the nominal 100 t/d that is being released at the summit approaches the low rates measured prior to the onset of the current Pu`u `O`o-Kupaianaha eruption, which started in 1983. Over the past several years, measurements of ERZ SO2 emission rates during active periods have yielded 2,000 t/d + 500 t/d, but during the recent episodic lull in eruptive activity, ERZ emissions declined to less than 10% of this level. During periods of fluctuating eruptive activity, SO2 emission rate measurements, with geophysical observations, are a useful tool for assessing eruptive status and dynamics.

Harris, A.J.L., Keszthelyi, L., Flynn, L.P., Mouginis-Mark, P.J., Thornber, C.R., Kauahikaua, J.P., Sherrod, D.R., and Trusdell, F.A., 1997, Near-real-time monitoring of effusive volcanic eruptions from geostationary satellites [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 6, p. A-165.

We show that GOES-9 weather satellite data can be used to monitor effusive volcanic eruptions. The GOES Imager infrared detectors have the appropriate sensitivity to detect even quite small (-0.2 km^2) effusive events via their thermal emissions. While the data have poor spatial resolution(4 km/pixel) and are affected by clouds, they are freely available, in near-real-time, every 15 minutes. The activity during and around episode 54 of the ongoing eruption of Kilauea (Hawaii) was used to demonstrate the utility and limitations of this type of monitoring. Prior to episode 54, Kilauea was feeding lava into the sea via a stable 10-km-long tube system. The thermal anomaly from the ocean entry was clearly visible in the GOES data and increased thermal radiance due to upslope breakouts could be identified. Episode 54 itself consisted of 22 hours of fissure-fed fountaining located 2-4 km uprift of the Pu`u `O`o vent, starting at 2:40 AM, January 30, 1997. A total of 6 different fissure segments (A-F) opened, and the Pu`u `O`o cone underwent a major collapse and ceased to issue lava. Following the shut-down of Pu`u `O`o, draining of the tube system was evident in the GOES data from diminished thermal radiance at the ocean entry pixels. The GOES data were also able to clearly indicate the time of fissure opening and shut down with few exceptions: fissure A shut down while the detector was still saturated by activity from fissures B and C, and clouds partially obscured the shut-off of fissure F. GOES data were also used to pinpoint the time of the reappearance of a lava lake within Pu`u `O`o and the start of episode 55. Work is underway at the University of Hawaii to automatically feed processed GOES data into the USGS Hawaiian Volcano Observatory for near-real-time analysis.

Harris, A.J., Keszthelyi, L., Flynn, L.P., Mouginis-Mark, P.J., Thornber, C., Kauahikaua, J., Sherrod, D., and Trusdell, F., 1997, Chronology of the episode 54 eruption at Kilauea Volcano, Hawaii, from GOES-9 satellite data: Geophysical Research Letters, v. 24, no. 24, p. 3281-3284.

The free availability of GOES satellite data every 15 minutes makes these data an attractive tool for studying short-term changes on cloud-free volcanoes in the Pacific basin. We use cloud-free GOES-9 data to investigate the chronology of the January 1997, episode 54 eruption of Kilauea Volcano, Hawaii. Seventy-six images for this effusive eruption were collected over a 60-hour period and show the opening and shutdown of active fissures, the draining and refilling of the Pu`u `O`o lava lake, and the cessation of activity at the ocean entry.

Heliker, C., and Wright, T.L., 1997, Ongoing eruption of Kilauea volcano devastates coastal communities [abs.]: Eos, Transactions, American Geophysical Union, v. 78, no. 17, p. S51. [AGU-MSA-GS spring meeting, Baltimore, MD, May 27-30, 1990, Program and abstracts]

The Island of Hawaii is still growing, thanks to the frequent eruptions of Kilauea and Mauna Loa, two of the most active volcanoes on earth. Living in such a geologically dynamic environment has its rewards - and its hazards. Most Hawaiian eruptions produce fluid lava flows that can travel many miles from their source. Such flows are the volcanic hazard most likely to have a serious impact on island residents and their property. In the 800 years since Hawaiians settled the shoreline of Kilauea, more than 80 [% of] the volcano's surface has been covered by fluid, basaltic lava flows. The ancient Hawaiians adapted to volcanic activity; modern communities with their greater dependence on permanent structures, highways, and utilities, are more vulnerable.
The current eruption on Kilauea's east rift zone, which began in January 1983, ranks as the volcano's most destructive episode of the last two centuries. Since 1987, lava flows have entered the ocean along Kilauea's southern coast almost continuously, adding over 500 acres of new land to the island. But in the process of creating new real estate, the flows have destroyed old. Lava flows have repeatedly invaded the small coastal communities just outside Hawaii Volcanoes National Park, destroying 181 houses. Inside the Park, a visitor center and many important archeological sites have been buried forever. Eight miles of the state highway that parallels the shore have been resurfaced by pahoehoe lava.
Once the flows reached the flat-lying coastal plain, they spread out, increasing the range of devastation. The Kupaianaha flowfield, which was responsible for most of the destruction outside the park, is three times as wide at the coast as it is on the steep slopes above.
In 1990, the flows turned toward Kalapana, an area treasured for its historic sites and black sand beaches. By the end of the year, all of these landmarks lay buried under 50 feet of lava. During this crisis, the USGS worked closely with the agencies responsible for public safety, providing information on lava flow location and movement to guide their decisions to close roads and evacuate residents.
In May 1990, President Bush signed a Federal Disaster Declaration for the Kalapana area. Following the declaration, the Federal Emergency Management Agency worked with the USGS and state and county agencies on a plan to mitigate future volcanic disasters on the island. FEMA based their recommendation to limit development on and near Kilauea's east rift zone on the lava-flow hazard zone map published by the USGS. This map is based on the location of active vents, the frequency of past lava coverage, and the topography of the volcanoes.
Since 1992, lava flows from the ongoing eruption have remained within the National Park, reducing the immediate threat to residential areas. The pattern of Kilauea's activity during the last three centuries, however, suggests that the current eruption will be followed by other eruptions on the east rift zone, posing a renewed threat to downslope communities.

Heliker, C., Stauffer, P.H., and Hendley, J.W.I., 1997, Living on active volcanoes--the island of Hawaii: U.S. Geological Survey Fact Sheet 074-97, (Reducing the Risk from Volcano Hazards series), 2 p.

People on the Island of Hawaii face many hazards that come with living on or near active volcanoes. These include lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and tsunami (giant seawaves). As the population of the island grows, the task of reducing the risk from volcano hazards becomes increasingly difficult. To help protect lives and property, USGS scientists at the Hawaiian Volcano Observatory closely monitor and study Hawaii's volcanoes and issue timely warnings of hazardous activity.

Heliker, C.C., Sherrod, D.R., Thornber, C.R., and Kauahikaua, J.P., 1997, Kilauea Volcano east rift zone eruption update: 1997 brings era of instability [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F648. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

The Pu'u 'O'o-Kupaianaha eruption of Kilauea is in its 15th year. From 1993-96 (eruptive episode 53), a single vent on the west flank of the Pu'u 'O'o cone fed lava to the ocean almost continuously. This period of steady-state effusion ended on January 29, 1997, when the Pu'u 'O'o crater pond drained and the summit of the cone collapsed. The next day, a new fissure, 4 km uprift, erupted for 22 hrs (episode 54). A 23-day hiatus in the eruption, the longest since 1986, followed episode 54. Episode 55 began on February 24, when a lava pond returned to the Pu'u 'O'o crater. Lava first erupted outside of the crater on March 28, and for the next three months the eruption shifted among four main vents on the west and south flanks of the Pu'u 'O'o cone. During this interval, flows extended less than 4 km from Pu'u 'O'o, both because activity at the vents was erratic and because the eruption was interrupted by ten pauses, ranging in duration from 3 to 15 hours. As a result of the numerous short flows, the episode 50-53 shield, which abuts the west flank of the Pu'u 'O'o cone, gained 35 m in height.
In late April, the active lava pond that had occupied Pu'u 'O'o crater almost continuously since 1990 was replaced by a single vent on the western side of the crater. Flows from the "crater cone" intermittently formed a rootless lava pond. In mid-June, the pond rose until it overtopped the gap in the west wall of Pu'u 'O'o formed by the January 1997 collapse. Lava spilled from the crater for the first time in 11 years. In early August, lava also overtopped the east crater rim, sending flows 1.5 km downrift. These spillovers lasted less than 4 hours, ending when the lava drained through conduits in the crater floor.
By July, the dominant vent outside the cone was the "south shield", which formed in June, 300 m south of Pu'u 'O'o. Sustained effusion from this vent fed flows that finally reached the ocean on July 12, near the eastern boundary of Hawaii Volcanoes National Park. In July and August, the lava flux ranged from 250,000-1,000,000 m3/day (determined by geoelectrical measurements using Very Low Frequency profiles over lava tubes). From April through July 1997, the MgO content of episode 55 lava increased from 7.7 to 8.1 wt percent. This lava is less fractionated than the rift-stored lava of episode 54 (5.5- 6.5 wt percent MgO) and is approaching the more primitive olivine-saturated compositions erupted late in episode 53 (8.4-8.8 wt percent MgO).

Hinkley, T., Wilson, S.A., Lamothe, P.J., Landis, G.P., Finnegan, D.L., Gerlach, T.M., and Thornber, C.R., 1997, Metal emissions from Kilauea--propertions, source strength, and contribution to current estimates of volcanic injection to the atmosphere [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F803. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

Ordinarily-rare metals are abundant in the plumes of quiescently-degassing volcanoes. These include volatile metals such as Pb, Cd, Cu, Zn, Tl, In, Sb and others. Collections of metals from the Kilauea plume have been made during the present eruptive cycle which began in 1983, most recently in 1996. Metal emissions are assessed by normalizing to those of sulfur, for which total emissions are closely monitored at Kilauea and some other volcanoes in the world. We measured metals by ICP-MS, and sulfur and other anionic species by ion chromatography. Kilauea is representative of an important volcanic type (hotspot, basaltic) and its emissions are significant for defining worldwide fluxes. It emits metals in proportions different from those reported from other volcanoes (at Kilauea, Pb:Cd:Cu:Zn are 1:2.5:6:~30; compare Indonesia 1:0.01-0.1:0.1-2:0.1-0.2. The metal proportions, and metal-to-sulfur ratios, vary less wildly over short times at Kilauea than elsewhere. The Kilauea metal emissions also have different proportions from what has been suggested as a worldwide volcano average (Nriagu, 1988, Pb:Cd:Cu:Zn are 1:0.3:3:3). Also different from worldwide estimates are the metal/sulfur ratios at Kilauea, which appears to emit only about half of the metal per unit of sulfur that has been proposed worldwide: Kilauea might be expected to emit more than the average, because its low-viscosity lava should rapidly convect metals to the melt-vapor interface, feeding its plume. Worldwide estimates of volcanic metal emissions currently rely on data predominantly from surprisingly old, pioneering studies. If these estimates are accepted, Kilauea might account for 3-4 percent of the worldwide total metal emissions.
The problem of why ordinarily-rare metals are abundant in the atmospheric load (atmospheric deposition) persists after being known for several decades, and proposed contributions to the anomaly by ocean surface spray, plants, mineral surfaces, and anthropogenic activity have not been thoroughly documented. Recent data on long term deposition of rare metals in Antarctic ice suggest that volcanic metal emissions alone can account for the masses found in the ice, although the proportions of metals do not appear to correspond perfectly between the ice and volcanic emissions at Kilauea or other volcanoes (Pb dominates in ice of all ages). The depth-concentration profiles of trace metals in the oceans may be influenced or controlled by atmospheric deposition. Because Kilauea metal emission measurements differ from those at other volcanoes and from worldwide estimates, and because of the continuing uncertainty about he reasons for trace metal abundance in the atmospheric load, we feel that measurements of metal emissions should continue and should be extended, at Kilauea and at other quiescently-degassing volcanoes of key types around the world.

Kong, L.S.L., Okubo, P.G., Moore, G.F., Duennebier, F.K., Webb, S.C., Crawford, W.C., Macdonald, M.A., and Hildebrand, J.A., 1997, Crustal structure of Kilauea's south flank and Loihi Seamount [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p. 23. [Geological Society of America, 93rd Annual Cordilleran Section meeting, Kailua-Kona, HI, May 21-23, 1997]

During the 1994, Loihi-Kilauea seismic experiment, over 200 km of seismic line were collected using a 4-element air gun array (2775 cu in) fired at 100-150 m intervals. Data were recorded by the 52-station permanent Hawaiian Volcano Observatory seismic network and three portable seismometers on land, and four ocean-bottom instruments, 10 sonobuoys, and a 6-channel seismic streamer at sea. Coherent P wave energy is identifiable on a majority of Kilauea's seismic stations out to 40-50 km, and detectable out to ranges as great as 85 km. PmP reflections from the crust-mantle boundary are observed from 30-50 km range, and PcP reflections from the volcano-crust boundary from 20-30 km range. Rays passing through Kilauea and Mauna Loa's magma conduit systems were not well-detected. A 15° attenuative shadow zone at 45-50 km range sampling 10-15 km depths, but not extending more than 3 km south of the caldera, is observed from waves passing through Kilauea's magmatic system; along the east rift zone, this volume extends to depths of 5-10 km (23-30 km range), but only downrift to Pu'u O'o. A reflection section across Kilauea's south flank shows ponded sediments on a topographic bench, suggesting that two slumps comprise the submarine portion with the landward block responding to the active Hilina fault system. All lines show mass-wasting to be the dominant slope-forming process. Velocities <4 km/s characterize the uppermost crust immediately offshore from the former Wahaula visitor center, where numerous subaerial bench collapses contribute to the steep submarine slope; talus debris extend 10 km offshore with nearshore thicknesses of ~1.5s 2-way travel time. The Loihi-to-shore reflection line shows a landward-dipping reflector extending upwards to within 0.1 s of the sea bottom; this structure could be related to a previous landslide episode which slumped along a listric fault surface and left a hummocky seafloor near its seismometer and hydrophone records. Velocities from 3.5 to 5 km/s describe the uppermost 1-2 km of crust beneath the summit region of Loihi, with a 4.8 km/s isovelocity layer (seen to 8 km range) characterizing the central summit. Lower velocities (3.5 km/s) describe the shallowmost crust between Loihi and the shore.

Lisowski, M., Miklius, A., Sako, M., Owen, S., and Segall, P., 1997, Deformation monitoring at the Hawaiian Volcano Observatory: recent results and future plans [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p. 25. [Geological Society of America, 93rd Annual Cordilleran Section meeting, Kailua-Kona, HI, May 21-23, 1997]

Active Hawaiian volcanoes are subject to a number of volcanic and tectonic forces that act over a wide range of time scales. The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) deformation monitoring program strives to accurately track ground movements over intervals from seconds to decades. We use repeated campaign-style leveling, trilateration, and GPS surveys to obtain good areal coverage and to resolve long-term rates of deformation. These surveys reveal very high rates of deformation concentrated on the summits and south flanks of Kilauea and Mauna Loa Volcanoes. For example, over the last decade, we've measured up to 8 cm/yr of seaward movement of Kilauea's south flank and up to 10 cm/yr of subsidence at its summit. On Mauna Loa, we've recorded southeastward motion of the southeast flank at rates of up to 4 cm/yr, and uplift at the summit of up to 5 cm/yr. These movements have occurred at nearly constant rates on Kilauea, but numerous short-period events, including dike intrusions and earthquakes, punctuate these motions. Until recently, a network of platform and shallow borehole tiltmeters provided our only continuous monitor. Our ability to track ground movements on Kilauea over short intervals was enhanced in 1995 and 1996 with the installation of 13 continuously recording GPS stations. Stanford University and HVO cooperatively installed seven stations, and the University of Hawaii installed six stations. Episodic changes in the positions of the GPS stations are evident during eruption pauses, during Kilauea's summit intrusion on February 01, 1996, and at other times when there are no obvious volcanic events. We hope to enhance our real-time monitoring capability over the next several years by upgrading our Kilauea tiltmeter network and by adding a network of tiltmeters, strainmeters, and continuous GPS stations on Mauna Loa.

Lisowski, M., Miklius, A., Owen, S., and Segall, P., 1997, Surface deformation before and after the January 30, 1997, Napau Crater eruption along Kilauea Volcano's east rift zone [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F633-634. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

Dense temporal sampling of regional deformation is crucial to the detection, tracking, and understanding of episodic changes in the magmatic and tectonic systems of active volcanoes such as Kilauea. We use data from a 7-station continuous GPS network on Kilauea Volcano to track deformation in the months before and after the January 30, 1997, Napau Crater eruption. The GPS network is jointly operated by the USGS (Hawaiian Volcano Observatory) and Stanford University. No detectable short-term deformation anomalies preceded the eruption, which occurred during a period of sustained surface flows from the Pu'u 'O'o vent and after several months of slower than normal seaward movement of Kilauea's mobile south flank. The sporadic 20-hr-long eruption on January 30 occurred when magma intruded into a shallow 5-km-long, 2.5-km-deep, 2-m-wide dike reached the surface. Formation of this dike drained lava from a pond in the Pu'u 'O'o vent, located 4 km down rift, and tapped magma from other shallow storage areas in the summit and east rift zone. The volcano's shallow magma system rapidly repressurized during the 54-day-long pause in surface flows that followed the eruption. Inflation of the shallow summit magma chamber was relatively steady, except for a brief episode of deflation that was followed by renewed extension across the east rift zone. Shortly afterward, a lava pond reappeared at Pu'u 'O'o. Sustained extension across the summit and east rift zone continued for several weeks as the shallow magma system filled. This extension slowed when surface flows began again from Pu'u 'O'o. Following the intrusion, seaward movement of coastal stations on Kilauea's south flank increased to rates typical of those measured over the last few years and has remained relatively steady to the present time.

Lockwood, J., and Trusdell, F., 1997, Summit and northeast rift zone, Mauna Loa (Trip 11), in Batiza, R., Lee, P., and McCoy, F., ed(s)., Molokai and Lanai, Maui, and Hawaii field trip guide: [s.l.], Geological Society of America, 6 p. [unpag.]. [Prepared for the 93rd annual Cordilleran section meeting, Geological Society of America, Kailua-Kona, HI, May 21-23, 1997]

[no abstract]

Mangan, M.T., and Lowenstern, J., 1997, Volcano Hazard Program five-year science plan--1998 to 2002: U.S. Geological Survey Open-File Report 97-680, 20 p.

The United States has 65 active and potentially active volcanoes. During the twentieth century, volcanic eruptions in Alaska, California, Hawaii, and Washington have devastated thousands of square miles of land and caused substantial economic and societal disruption and, in the worst instances, loss of life. The Volcano Hazards Program (VHP) seeks to lessen the harmful impacts of volcanic activity by monitoring active and potentially active volcanoes, assessing their hazards, responding to volcanic crises, and conducting research on how volcanoes work. To fulfill a Congressional mandate (P.L. 93-288) that the USGS issue "timely warnings" of potential geologic hazards to responsible emergency-management authorities and the populace affected, the VHP strives to obtain the best possible scientific information about volcanic hazards and to communicate it effectively to the authorities and the public in an appropriate and understandable form.

Mangan, M.T., Clarke, A., Cole, P., Harford, C., Hoblitt, R., Rowley, K., and Watts, R., 1997, Soufriere Hills Volcano, Montserrat: the destructive pyroclastic flows of 25 June 1997 [abs.]: Eos, Transactions, American Geophysical Union, v. 78, no. 46, p. F780 . [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

The Soufriere Hills Volcano on the East Caribbean island of Montserrat is an andesitic dome complex surrounded by an apron of block and ash flows and associated lahars. After ~350 years of dormancy, the volcano reawakened in July 1995 with a burst of phreatic activity, followed in September 1995 by extrusive dome growth and pyroclastic flow (pf)-generating dome collapses that continue to the present. The volcano's most destructive act was struck on 25 June 1997 when ~4.9x106 m3 of the north face of the active dome collapsed, producing pfs that destroyed 150 homes and claimed 19 lives. By early June 1997, the dome had amassed ~65x106 m3 of andesitic lava and attained a height of ~1010 m ASL. Throughout the month, rockfalls and minor pfs were shed from the dome's eastern, northeastern, and northern faces. On the morning of 25 June, unusually intense rockfall activity deposited blocks at the base of the dome in Mosquito Ghaut, a major drainage on the north flank of the volcano. In the early afternoon, a dilute ash cloud billowed out of the summit of the dome above Mosquite Ghaut. Fifteen minutes later (~1300 hrs), a dark coluimn of ash shot upward to a height of ~14 km, signaling a major dome collapse. Over the next 25 minutes, a succession of three pfs swept down the flanks of the volcano. The dense underflows (block and ash) traveled at speeds of ~25 m/s northeastward down Mosquite Ghaut to the coastline (regional slope of ~10¡). Scouring of the valley walls indicate that the flows were inflated up to 8 times their final thickness over runout distances of ~6.5 km during transit. The distal margins contained blocks up to 5 m across and exhibited temperatures of >642¡C four weeks after emplacement. The overlying turbulent ash cloud flattened trees on the ridges at the head of Mosquite Ghaut and surged ~2.5 km to the WNW. The western margin of the surge drained into a small valley and flowed an additional 3.5 km to the west. The surge carried a small proportion of <0.5 m blocks over distances of ~2 km. Overall, ~4 km2 of the island received deposits ranging in thickness from a few tens of centimeters (western valley) to 15 meters (lower Mosquito Ghaut and coastal areas). The collapse lopped off ~60 m of the dome's summit relief and created a steeply-dipping, spoon-shaped scar in its northern face. Almost immediately, the dome began to extrude new lava. By 1 July, roughly 65% of the scar had refilled (effusion rate of ~6m3/s).

Mattox, T.N., and Mangan, M.T., 1997, Littoral hydrovolcanic explosions: a case study of lava-seawater interaction at Kilauea Volcano: Journal of Volcanology and Geothermal Research, v. 75, no. 1-2, p. 1-17.

A variety of hydrovolcanic explosions may occur as basaltic lava flows into the ocean. Observations and measurements were made during a two-year span of unusually explosive littoral activity as tube-fed pahoehoe from Kilauea Volcano inundated the southeast coastline of the island of Hawai`i. Our observations suggest that explosive interactions require high entrance fluxes (³4 m3/s) and are most often initiated by collapse of a developing lava delta. Two types of interactions were observed. "Open mixing" of lava and seawater occurred when delta collapse exposed the mouth of a severed lava tube or incandescent fault scarp to wave action. The ensuing explosions produced unconsolidated deposits of glassy lava fragments or lithic debris. Interactions under "confined mixing" conditions occurred when a lava tube situated at or below sea level fractured. Explosions ruptured the roof of the tube and produced circular mounds of welded spatter. We estimate a water/rock mass ratio of 0.15 for the most common type of littoral explosion and a kinetic energy release of 0.07-1.3 kJ/kg for the range of events witnessed.

Table of Contents
Introduction 1
Littoral setting 4
Types of explosions 6
Tephra jets
Lithic blasts
Lava bubble bursts
Littoral lava fountains
Explosion mechanisms 12
Open mixing
Confined mixing
Summary and discussion 15
Acknowledgements 15
References 16

McNutt, S.R., Ida, Y., Chouet, B.A., Okubo, P., Oikawa, J., and Saccorotti, G., 1997, Kilauea Volcano provides hot seismic data for joint Japanese-U.S. experiment: Eos, Transactions, American Geophysical Union, v. 78, no. 10, p. 105-111. [Authors comprise the Japan-U.S. Working Group on Volcano Seismology]

A team of 25 researchers from the United States, Japan, and Italy joined the staff of the Hawaiian Volcano Observatory (HVO) from January 8 through February 9, 1996, to make the most detailed seismic recordings on Kilauea Volcano ever. One-hundred-sixteen portable seismographs were installed in and near Kilauea Crater in Hawaii Volcanoes National Park as a joint Japanese-U.S. research project to record volcanic earthquakes and tremor. The importance of these events has long been recognized, but their origin remains poorly understood due to inadequate network coverage and limitations of the analog instrumentation used in the past.
On February 1, a swarm of over 500 earthquakes was recorded by the dense network, providing the best recording of an intrusive earthquake swarm at Kilauea. The data collected offer an unprecedented opportunity to understand earthquakes associated with magma transport.

McNutt, S.R., Ida, Y., Chouet, B.A., Okubo, P., Oikawa, J., and Saccorotti, G., 1997, Kilauea Volcano provides hot seismic data for joint Japanese-U.S. experiment: Eos, Transactions, American Geophysical Union, v. 78, no. 10, p. 105-111. [Authors comprise the Japan-U.S. Working Group on Volcano Seismology]

[Abstract needed]

Miklius, A., Coloma, F., Denlinger, R., Lisowski, M., Owen, S., Sako, M., and Segall, P., 1997, Gobal Positioning System measurements on the island of Hawaii: 1993 through 1996: U.S. Geological Survey Open-File Report 97-698, 114 p.

Global Positioning System (GPS) measurements on the island of Hawaii began in 1987 and have proven to be a very effective tool in monitoring ground deformation associated with volcanic and volcano-tectonic activity (e.g. Dvorak, 1994; Owen et al., 1995). Sources of deformation on Hawaii include the magma chambers beneath the summits of Kilauea and Mauna Loa, the magma systems in their rift zones, and slip along detachment faults beneath the southern flanks of both volcanoes. From 1993 through 1996, Kilauea Volcano erupted almost continuously on the east rift zone from various vents in the Pu'u 'O'o area (Figure 1), continuing the eruption that began in January of 1983. There were, however, numerous pauses in eruptive activity. Most of these lasted only one to two days, but several longer pauses occurred in 1993 and 1996. The 1993 pause followed an upper east rift zone earthquake swarm on February 7 and continued until lava erupted from a new vent on the side of Pu'u 'O'o cone on February 20 (Heliker et al., in press). A summit intrusion on February 1, 1996, preceded a surge in supply to the eruption site, followed by a 10-day pause in eruptive activity. Another substantial pause started on May 30 and lasted until June 4, 1996 (Thornber et al., 1996).

Mauna Loa volcano, which last erupted in 1984, remained quiescent. Only one earthquake of magnitude greater than 5 was recorded on the island during this reporting period. This was a M5.2 earthquake on February 1, 1994, that originated at about 32 km beneath the south flank of Kilauea.
The largest motions on the island from 1993 through 1996 were observed on the south flank of Kilauea (Figure 3), with maximum displacement rates of about 10 cm/yr, similar to rates observed with GPS from 1990 to 1993 (Owen et al., 1995a). However, not all stations moved at a constant rate over this time period. For example, displacement rates on Kilauea's south coast slowed to about 6 cm/yr between 1993 and 1994 (Owen et al., 1995b), and velocities on the southeastern flank of Mauna Loa varied from a maximum of over 4 cm/yr between 1993-94 to less than 2 cm/yr between 1995-96. The summit of Kilauea underwent substantial subsidence and contraction from 1993 to 1996, while Mauna Loa's summit, which had been extending and rising since its last eruption (Miklius et al., 1995), showed very low rates of deformation.
Figure 4 shows a time series of the data from the two longest-running continuous stations as an example of the data collected by the continuous GPS network. The network has shown great potential for monitoring both the long-term deformation and the variations in deformation rates that are crucial to understanding the relationship between the magma system and structure of Hawaii's active volcanoes.

Nakata, J., Honma, K., Tanigawa, W., Tomori, A., Furukawa, B., and Okubo, P., 1997, Seismographic monitoring of the active Hawaiian volcanoes [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p. 55. [Geological Society of America, 93rd Annual Cordilleran Section meeting, Kailua-Kona, HI, May 21-23, 1997]

Seismographic monitoring of the active Hawaiian volcanoes began in 1912. Since then, the seismographic network operated and maintained by the U.S. Geological Survey's Hawaiian Volcano Observatory has expanded to 64 station sites island-wide, generating continuously telemetered data, in real-time, on a total of 123 channels recorded at HVO. The network consists principally of high-gain, short-period instrumentation for use in earthquake monitoring and cataloging. Recent network upgrades include the implementation of direct-to-line technology, increasing telemetry bandwidth in the regional network, and the installation of a 10-station broadband, digitally telemetered subnetwork in the summit region of Kilauea Volcano.
Our network coverage is focused on Kilauea Volcano and, to a lesser extent, on the southeast flank of Mauna Loa Volcano. The monitoring capabilities of the regional network extend to other active volcanoes, Loihi and Hualalai, as well as to the numerous tectonic features on the island of Hawaii. At HVO, the telemetered data are recorded in analog and digital formats. The analog recordings are scanned for an overview of daily seismicity. Digital recordings are initially computer processed and analyzed, in near-real time. Automated identification of primary wave arrival times determines preliminary hypocentral parameters. Interactive data analysis follows in order to refine hypocentral estimates before data are archived onto magneto-optical disk. Continuous data from the entire network are also written onto digital audio tape.
We continue to monitor the seismicity of the current eruption of Kilauea's east rift zone. At the same time, we also catalog island-wide seismicity with particular attention to the possible eruption of the other volcanoes. 1996 was highlighted by a strong earthquake swarm, on February 1, beneath the summit of Kilauea. During July-August, we recorded several thousand submarine earthquakes associated with Loihi Volcano. Current and historical data are archived at HVO. The archive is maintained to provide data for scientific studies, administrative reports and general inquiries.

Owen, S., Segall, P., Lisowski, M., Miklius, A., Bevis, M., and Foster, J., 1997, The January 30, 1997 fissure eruption in Kilauea's east rift zone as measured by continuous GPS [abs.]: Eos, Transactions, American Geophysical Union, v. 78, no. 17, p. S105. [AGU-MSA-GS spring meeting, Baltimore, MD, May 27-30, 1990, Program and abstracts]

Stanford, HVO and UH have installed 13 continuous GPS receivers on Kilauea to study south flank stability and its relation to magmatic processes. On January 30, 1997, the continuous GPS network recorded the largest volcanic event to occur on Kilauea since the receivers were installed. Tremor was first detected by HVO seismometers at 0445 UTC near the eventual eruption site. New fissures erupted on the floor of Napau Crater and just east of the crater at around 1243 UTC. The fissures are located a few kilometers east of Pu`u O`o and 4 km west of the nearest continuous GPS stations (see Thornber et al., this volume, for further details of the eruption).
Rapid southward displacement of Kalapana Trail (KTPM), a station close to the fissure and south of the rift zone, started shortly after seismic tremor began and slowed at about the time of the fissure eruptions. The figure shows the north component of the baseline between a stable GPS station on Mauna Loa and KTPM, as estimated averaging over 40 minute intervals.
Continuous GPS sites spanning the summit help constrain the summit deformation, with a shallow deflation source within the summit caldera giving the best fit to the data. Preliminary analysis shows that the best-fitting model rift plane is less than 3 km deep, and dips towards the south, explaining the pronounced asymmetry in displacement about the rift. Early results do not require changes in slip-rate along the south flank decollement before, during, or immediately after the event [figure].

Owen, S., Miklius, A., Segall, P., Lisowski, M., and Sako, M., 1997, Displacements from the June 30, 1997 M5.5 Kilauea south flank earthquake and preceding decrease in slip rate [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F166. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

On June 30, 1997, a M5.5 earthquake occurred on the south flank of Kilauea. The quake's epicenter is located near the epicenter of previous large south flank earthquakes (M7.2, 1975; M6.1, 1989). Significant surface displacements were measured using GPS at more than 10 sites, 2 of them continuous, and the maximum coseismic surface displacement was 4.8 centimeters. The displacements from the earthquake are consistent with seaward slip along the decollement.
Prior to the M5.5 quake, a decrease in the velocity of several GPS sites was observed. These sites have been measured at least once a year since 1993. A comparison of the 1994-95 velocities with the 1995-96 velocities shows that seven stations had a statistically different velocity in the 1995-96 time period. Four sites near the 1997 epicenter decreased their seaward slip rates by at least 3 cm/yr. This decrease amounts to roughly 40 to 100% of the sites' 1994-5 velocities. In addition, the seaward velocity of two stations immediately north of the east rift zone increased by approximately 3 cm/yr. It is possible that these changes in velocity, which occurred in the same region as the 1997 M5.5 earthquake, are the result of a decrease in slip at depth on the decollement. A model allowing spatially variable slip along the fault plane has been developed, and will be used to test this hypothesis.
Whether or not the stations that experienced a decrease in velocity were moving at similar rates in 1996-97 is complicated by the occurrence of a shallow rift intrusion on January 30, 1997. Indeed, the rift intrusion itself may have triggered the M5.5 earthquake. Stress changes caused by the rift event will be computed and compared with the models of coseismic fault slip.

Owen, S., Lisowski, M., Segall, P., Miklius, A., and Sako, M., 1997, Kilauea's most recent rift event: a shallow rift eruption caused by long-term deep rift extension [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F634. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

The dense continuous GPS network on Kilauea, combined with traditional survey GPS data, have captured the most recent rift intrusion in Kilauea's East Rift Zone with unprecedented spatial and temporal coverage. The January 30, 1997 event included a small eruption at Napau Crater and several kilometers of ground cracking. Models of the surface displacements show that while the rift zone was extending and the summit magma chamber was deflating, a secondary magma storage area underneath Makaopuhi crater was also being drained. The rift plane is estimated to be 4.4 km ~0.7 km long, extending from near the surface to 2.4 ~1 km depth, with 2 m of opening across the plane. The estimated volume increase within the rift zone is an order of magnitude greater than the volume of magma estimated to have drained from the summit and the Makaopuhi storage areas.
Continuous GPS data shows that the long-term deflationary trend of the summit magma chamber continued up until the onset of the rift intrusion. This data suggests that the standard model for rift eruptions, magma being forced out of an overpressurized summit storage area, is not applicable for this event. Sub-hourly GPS solutions show rift dilation beginning 8 hours before the onset of the fissure eruption. No precursory slip along the basal decollement has been detected. In models of the GPS velocities for the 1992-6 time period, rift opening between 9 and 3 km is required to decouple the stable north flank from the rapidly displacing south flank, where stations are displacing seaward at rates up to 8 cm/yr. We suggest that this long-term deep dilation stressed the upper locked portion of the East Rift Zone, leading to the sudden shallow rift extension on January 30.

Realmuto, V.J., Sutton, A.J., and Elias, T., 1997, Multispectral thermal infrared mapping of sulfur dioxide plumes: a case study from the East Rift Zone of Kilauea Volcano, Hawaii: Journal of Geophysical Research, v. 102, no. B7, p. 15,057-15,072.

The synoptic perspective and rapid mode of data acquisition provided by remote sensing are well suited for the study of volcanic SO2 plumes. In this paper we describe a plume-mapping procedure that is based on image data acquired with NASA's airborne thermal infrared multispectral scanner (TIMS) and apply the procedure to TIMS data collected over the East Rift Zone of Kilauea Volcano, Hawaii, on September 30, 1988. These image data covered the Pu'u 'O'o and Kupaianaha vents and a skylight in the lava tube that was draining the Kupaianaha lava pond. Our estimate of the SO2 emission rate from Pu'u 'O'o (17-20 kg s-1) is roughly twice the average of estimates derived from correlation spectrometer (COSPEC) measurements collected 10 days prior to the TIMS overflight (10 kg s-1). The agreement between the TIMS and COSPEC results improves when we compare SO2 burden estimates, which are relatively independent of wind speed. We demonstrate the feasibility of mapping Pu'u 'O'o - scale SO2 plumes from space in anticipation of the 1998 launch of the advanced spaceborne thermal emission and reflectance radiometer (ASTER).

Scott, W.E., Gardner, C.A., Sherrod, D.R., Tilling, R.I., Lanphere, M.A., and Conrey, R.M., 1997, Geologic history of Mount Hood Volcano, Oregon - a fieldtrip guidebook: U.S. Geological Survey Open-File Report 97-263, 38 p.

This guidebook was prepared for a field trip that was part of the April 1996 meeting of the Cordilleran Section of the Geological Society of America, which was held in Portland, Oregon. The trip provides participants with a broad undrstanding of the evolution of Mount Hood volcano from stops at several view points and at outcrops that sample the range of eruptive products and other deposits around the volcano. The trip begins in Portland, follows U.S. Interstate Highway 84 (I-84) east through the Columbia River gorge, ascends Hood River Valley southward to Mount Hood, and returns to Portland along the Sandy River valley (frontispiece). Most of the stops are on public land, but Stop 2 and parking for Stop 3 are on private land. Mount Hood is a chiefly andesitic volcano of Quaternary age that has been built by a succession of lava-flow and lava-dome eruptions (Wise, 1968, 1969; Crandell, 1980). Its volume of about 50 km3 (Sherrod and Smith, 1980) is mid-sized among the major Cascade centers. The apparent lack of widespread pumiceous tephra deposits suggests that the volcano has not produced explosive plinian eruptions. From the perspective of its recent behavior, the greatest hazards posed by Mount Hood include (1) collapse of growing lava domes and generation of pyroclastic flows, which in turn melt snow and ice to form lahars that flow far down valleys; (2) the long-term adjustment of river channels to the large quantities of volcanogenic sediment dumped into valleys that head on the volcano; and (3) landslides of hydrothermally altered material from the steep upper slopes of the volcano that spawn debris avalanches and related lahars that sweep far downstream. The last class need not be associated with eruptive activity, but the triggering of the largest volume and farthest traveled events is likely heightened during periods of unrest as magma intrudes and deforms the volcano, accompanied by earthquakes and phreatic and magmatic explosions. The Mount Hood edifice occupies a long-lived focus of andesitic volcanism that, on the basis of our initial K-Ar results, has been recurrently active for the past 1.5 m.y. The cone of Mount Hood has been present for at least 0.5 m.y. By the conclusion of our work, we hope to have a well-constrained estimate of eruption rate throughout Quaternary time. The following discussion and figures summarize our current understanding of the stratigraphy and chronology of Mount Hood products. Many of our interpretations should be regarded as preliminary because numerous units remain undated and stratigraphic relations in many locations need further resolution.

Self, S., Cashman, K., Thornber, C., Keszthelyi, L., and Kauahikaua, J., 1997, Active and recent volcanism on Hawaii (Trip 4), in Batiza, R., Lee, P., and McCoy, F., ed(s)., Molokai and Lanai, Maui, and Hawaii field trip guide: [s.l.], Geological Society of America, 14 p. [unpag.]. [Prepared for the 93rd annual Cordilleran section meeting, Geological Society of America, Kailua-Kona, HI, May 21-23, 1997]

"This field workshop will examine the full range of recent and active styles of emplacement of Hawaiian basaltic lavas. It is hoped that during the workshop we will be able to share with the participants the most recent lessons and experiences gained by working on active and historical basaltic volcanism on Hawai'i and to gain new insights from active discussions in the field between participants working on a wide range of volcanological problems. This workshop is not a sight-seeing tour. Instead, it is designed to be most useful for those geologists currently dealing with basaltic volcanism (e.g., submarine lavas, planetary volcanism, paleomagnetism, igneous petrology, and/or stratigraphy in basaltic provinces) who have not had an opportunity to work extensively in Hawai'i."

Sherrod, D.R., for the Hawaiian Volcano Observatory Staff, 1997, Real-time data collection and public communication during eruptions at active shield volcanoes, Hawaii [abs.]: Eos, Transactions, American Geophysical Union supp., v. 78, no. 46, p. F38. [AGU fall meeting, San Francisco, CA, Dec. 8-12, 1997, Program and abstracts]

The U.S. Geological Survey's response during a typical eruption crisis at Kilauea, an active shield volcano, shows the elements of our real-time monitoring at the Hawaiian Volcano Observatory. Our first alert is commonly seismic, occurring when tremor alarms herald the migration of magma in the volcanic edifice. Tiltmeters across the volcano's summit and along the east rift zone trace the ground deformation as magma is injected as shallow intrusions. The seismic and ground deformation data are telemetered instantaneously to the Observatory. So too are images from remote surveillance cameras near Kilauea's active vent, which allow a near-constant visual assessment of the eruption. The video technique is limited by the fixed aspect of camera viewpoints and by weather, however, so personnel are commonly deployed early in a crisis, with guidance from the tilt and seismic data, to determine if new vents are forming in previously inactive areas. As lava erupts, we use high-precision hand-held GPS receivers to map flow boundaries, either by foot or helicopter. These data are downloaded at desktop computers to produce digital maps at any scale for reporting and analysis. Continuous monitoring of sulfur dioxide and carbon dioxide, and measurements of sulfur dioxide discharge, reveal changes in magmatic gas content and the attendant environmental effects downwind from the volcano. Fixed-site and campaign-style GPS data and conventional level-line surveys verify the magnitude and extent of deformation resulting from the magmatism. A future goal is to automatically track changes in the magma system by applying real-time GPS, tiltmeter, and borehole strainmeter data into computer code that models the swelling intrusive sources.
Information is released to an increasingly broad audience as the events unfold. The National Park Service, which manages land in much of the summit area, and Hawaii County Civil Defense are notified early in the alert, as soon as the tremor is verified and appears sustained. The call-down list expands to include the press and broadcast news media when the eruption begins-or sooner if the tremor provides sufficient warning. Conventional press releases are issued by fax and e-mail and posted on our web site.

Sherrod, D.R., Mastin, L.G., Scott, W.E., and Schilling, S.P., 1997, Volcano hazards at Newberry Volcano, Oregon: U.S. Geological Survey Open-File Report 97-513, 14 p.

Newberry volcano is a broad shield volcano located in central oregon (dfig. 1). It has been built by thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during several eruptive episodes of the past 10,000 years. The most recent eruption 1,300 years ago produced the Big Obsidian Flow. Thus, the volcano's long history and recent activity indicate that Newberry will erupt in the future. The most-visited part of the volcano is Newberry Crater, a volcanic depression or caldera at the summit of the volcano. Seven campgrounds, two resorts, six summer homes, and two major lakes (East and Paulina Lakes) are nestled in the caldera. The caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Other eruptions during this time have occurred along a rift zone on the volcano's northwest flank and, to a lesser extent, the south flank. Many striking volcanic features lie in Newberry National Volcanic Monument, which is managed by the U.S. Forest Service. The monument includes the caldera and extends along the northwest rift zone to the Deschutes River. About 30 percent of the area within the monument is covered by volcanic products erupted during the past 10,000 years from Newberry volcano. Newberry volcano is presently quiet. Local earthquake activity (seismicity) has been trifling throughout historic time. Subterranean heat is still present, as indicated by hot springs in the caldera and high temperatures encountered during exploratory drilling for geothermal energy. This report describes the kinds of hazardous geologic events that might occur in the future at Newberry volcano. A hazard-zonation map is included to show the areas that will most likely be affected by renewed eruptions. In terms of our own lifetimes, volcanic events at Newberry are not of day-to-day concern because they occur so infrequently; however, the consequences of some types of eruptions can be severe. When Newberry volcano becomes restless, be it tomorrow or many years from now, the eruptive scenarios described herein can inform planners, emergency response personnel, and citizens about the kinds and sizes of events to expect.

Sherrod, D.R., Taylor, E.M., Ferns, M.L., Scott, W.E., Conrey, R.M., and Smith, G.A., in press, Geologic map of the Bend 30- by 60-minute quadrangle, central Oregon: U.S. Geological Survey Miscellaneous Investigations Map, scale 1:100,000.

Sutton, A.J., and Elias, T., 1997, Volcanic gases, vog and laze: what they are, where they come from, and what they do [abs.], in Vog and Laze Seminar, Hilo, HI, Nov. 1997, Abstracts: Hilo, HI, University of Hawaii at Hilo, Center for the Study of Active Volcanoes, [unpag.]. [Sponsored by the Federal Emergency Management Agency]

Airborne volcanic pollution in Hawaii became a widespread public concern in mid-1986, when activity at Kilauea volcano changed from short episodes of vigorous fountaining, occurring about once every three weeks, to a more constant discharge of lava and gas. Of the several gases released from Kilauea, sulfur dioxide (SO2) is the major species responsible for airborne pollution. SO2 is an irritant which can cause bronchoconstriction, especially in asthmatics, and can also impede the ability of the upper respiratory tract to rid itself of other harmful substances. Kilauea currently releases about 2,000 metric tonnes of SO2 gas each day (T/d) during active eruption and 200 T/d during eruptive pauses. In the absence of strong winds, the gas accumulates in the air, sometimes reaching levels that exceed the Environmental Protection Agency's 24-hour primary health standard of 0.14 parts per million. Since 1986, this has occurred more than 70 times within Hawaii Volcanoes National Park.
Another tuype of pollution results when molten lava enters the ocean, evaporating seawater. A vigorous physical and chemical interaction results in the generation of a large "laze" steam plume laden with hyudrochloric acid. This plume poses a local hazard, especially for people who visit ocean entry sites.
The SO2 and other gases emitted from Kilauea combine and react chemically with oxygen, atmospheric moisture, dust and sunlight over periods of minutes to days to form the hazy pollution we know as vog. Vog is composed primarily of gas, tiny particles and droplets (aerosols), including sulfuric acid and other sulfate compounds. SO2 gas is a significant component of volcanic pollution at locations close to the main gas emission source, currently Halema`uma`u at the summit of Kilauea, and Pu`u `O`o on the east rift zone. However aerosols dominate at greater distances from emission sources. Trace amounts of several toxic metals, including selenium, mercury, arsenic and iridium have also been measured in aerosols derived from Kilauea's emissions.
Although the measured amount of aerosol in Hawaii's air does not routinely exceed Federal health standards, the unique combination of SO2 gas, acidic particles, and trace amounts of toxic metals in volcanic pollution from Kilauea may account for the wide range of human health symptoms reported. These anecdotal symptoms vary considerably among individuals, but can include headaches, breathing difficulties, increased susceptibility to respiratory ailments, watery eyes, sore throat, flu-like symptoms and a general lack of energy.
During prevailing tradewind conditions, the nearly constant stream of emissions from Kilauea is blown to the southwest where wind patterns send it up the Kona coast. Here, some of the vog becomes trapped by daytime (onshore) and night time (offshore) sea breezes. Traces of vog aerosol have been detected as far away as Johnston Island, 1000 miles to the southwest of Hawaii. In contrast, when tradewinds are absent, or when light southerly (Kona) winds blow, much of the volcanic air pollution remains in east Hawaii. Under sustained Kona winds, vog reaches Oahu, 230 miles to the northwest. The present level of volcanic air pollution on the Island of Hawaii will probably persist as long as the current steady effusion of lava and gas continues.

Sutton, A.J., Elias, T., and LaHusen, R., 1997, Some results from continuous monitoring of SO2 and CO2 at Kilauea Volcano, Hawaii [abs.], in IAVCEI, 6th Field Workshop on Volcanic Gases, Hawaii National Park, HI, May 1997, Abstracts: Hawaii National Park, HI, U.S. Geological Survey, University of Hawaii at Hilo, Center for the Study of Active Volcanoes, [unpag.]. [Sponsored by International Association of Volcanology and Chemistry of the Earth's Interior]

Data from continuous monitoring of volcanic gases has shown that gas release "events" sometimes correlate with changes in a volcanic system measured by geophysical methods. These gas events, however, may occur on a time scale too short (minutes to hours) to be reliably detected by emission-rate studies such as COSPEC, or by intermittent field sampling with laboratory analysis. We are testing a self-contained, species-selective system for continuous, in-situ monitoring of ambient CO2 and SO2 at remote locations on Kilauea's summit and East Rift Zone. Wind-vector data and fumarole temperature are also monitored by the system to better interpret the ambient gas measurements. Data collected so far, synthesized with other geochemical and geophysical measurements has, over the past year, recorded significant changes in Kilauea's eruptive status and style.

Sutton, J., Elias, T., Hendley, J.W.I., and Stauffer, P.H., 1997, Volcanic air pollution--a hazard in Hawaii: U.S. Geological Survey Fact Sheet 169-97, (Reducing the Risk from Volcano Hazards series), 2 p.

Noxious sulfur dioxide gas and other pollutants emitted from Kilauea Volcano on the Island of Hawaii react with oxygen and atmospheric moisture to produce volcanic smog (vog) and acid rain. Vog poses a health hazard by aggravating preexisting respiratory ailments, and acid rain damages crops and can leach lead into household water supplies. The U.S. Geological Survey's Hawaiian Volcano Observatory is closely monitoring gas emissions from Kilauea and working with health professionals and local officials to better understand volcanic air pollution and to enhance public awareness of this hazard.

Swanson, D.A., 1997, Geologic map of the Packwood Quadrangle, southern Cascade Range, Washington: U.S. Geological Survey Open-File Report 97-157, scale 1:24,000, 18 p.

[No abstract]

Swanson, D.A., 1997, Uplift of the southern Washington Cascades in the past 17 million years, 1997, [abs.]: Geological Society of America Abstracts with Programs, v. 29, no. 5, p. 68. [Geological Society of America, 93rd Annual Cordilleran Section meeting, Kailua-Kona, HI, May 21-23, 1997]

The Grande Ronde Basalt is a widespread datum against which to gauge the amount of uplift in the southern Washington Cascades. The contact between the two youngest magnetostratigraphic units (N2 over R2) in the Grande Ronde can be mapped across the Columbia Plateau to the Cascades. The nearly uniform southwestward slope of the Plateau (1.8 m/km) from the Idaho panhandle to central Washington suggests little deformation (aside from gentle tilting toward pasco Basin) and hence little change in elevation of the N2-R2 contact (670 m) in the Spokane-Coeur d/Alene area (the "Coeur d/Alene datum"). The difference in elevation between this datum and the N2-R2 contact in the Washington Cascades, which ranges in elevation from 830 m to more than 2 km, is a measure of the amount of uplift since R2 time (16-17 Ma). However, the actual uplift was greater, because the basalt moved westward down an unknown though surely small gradient, as judged from the broad extent and sheetlike nature of single flows. For example, at a primary gradient of 1 m/km, the contact would have had a pre-uplift elevation of about 330 m along the east base of the Cascades, 360 km west of Coeur d'Alene datum. At a gradient of 0.2 m/km, the elevation would have been about 600 m. The maximum amount of uplift, west of Yakima, relative to these elevations is 1.7 km and 1.4 km respectively. The uplift decreases to 0.5 km and 0.2 km, respectively, both southward near the Columbia River and northward west of Ellensburg. The uplift partly relflects folding at the subdued western end of the Yakima fold belt, but the area of greatest uplift, west of Yakima, extends more than 2 km north-south across projected fold axes and indicates uplift along the Cascades. The highest basalt projects westward above the goat Rocks, a large Pliocene-Pleistocene eruptive center along the Cascade crest. The 1-Ma Tieton Andesite, erupted in the Goat Rocks, moved 80 km eastward down the old Tieton River. Today's gradient of the old river, defined by elevations of the contact between the andesite flow and underlying stream gravel, is steeper than that of the modern river (15.5 m/km vs. 9.9 m/km in Tieton River canyon, 5-27 km from the river mouth). Stream power, measured by gravel size, is similar for the ancient and modern rivers, however, and suggests similar original gradients. The Tieton Andesite may therefore have been tilted eastward 5.6 m/km during Cascade uplift to account for the difference between the original and modern gradients.

Thatcher, W., Marshall, G., and Lisowski, M., 1997, Resolution of fault slip along the 470-km-long rupture of the great 1906 San Francisco earthquake and its implications: Journal of Geophyusical Research, v. 102, no. B3, p. 5353-5367.

Data from all available triangulation networks affected by the 1906 earthquake have been combined to assess the trade-off between slip resolution and its uncertainty and to construct a conservative image of coseismic slip along the rupture. Because of varying network aperture and sttion density, slip resolution is very uneven. Although slip is determined within uncertainties of +1.0 m along 60% of the fault, constraints are poor on the remaining, mostly offshore portions of the rupture. Slip decreases from maxima of 8.6 and 7.5 m at Shelter Cove and Tomales Bay to 4.5 m near Mount Tamalpais and 2.7 m at Loma Prieta. The geodetically derived slip distribution is in poor agreement with estimates based on analysis of S wave seismograms, probably because these waves register only 20-30% of the total seismic moment obtained from longer-period surface waves. Consideration of a range of fault geometries for 1906 slip near Loma Prieta indicates right-lateral motions lie between 2.3 and 3.1 m. These values are considerably greater than the 1.5 m of measured surface slip on which several assessments of high earthquake hazard for this fault segment were based. This factor, along with the absence of 1989 slipping where 1906 surface slip was used to make the forecasts, casts doubt ojn some claims of success in predicting the 1989 M - 6.9 Loma Prieta earthquake.

Thornber, C.R., 1997, HVO/RVTS-1: a prototype remote video telemetry system for monitoring the Kilauea east rift zone eruption, 1997: U.S. Geological Survey Open-File Report 97-537, 19 p.

HVO/RVTS-1, a prototype Remote Video Telemetry System, is currently in use at the U.S. Geological Survey's Hawaiian Volcano Observatory (HVO). Recording of video images transmitted at near real-time from the currently active Pu'u 'O'o vent on the east rift zone of Kilauea Volcano, began in early April 1997. Since that time, the RVTS-1 has proven its value and reliability as an eruption monitoring device and promises to be a long-lived addition to HVO's real-time instrumental array.
The system comprises a unique configuration of mostly "off-the-shelf" products. The key components are a HyperScan(tm) digital transmitter module and a desktop computer with HyperScan(tm) receiver software (Sensormatic, Inc.). The high-speed broad-band radio communication link is achieved using FreeWave(tm) Wireless Data Transceivers (Free Wave Technologies, Inc.). The receiver software package allows for near-real-time, high-resolution image display along with storage and review of digital images in a moving picture mode.
This report provides a technical overview of the first remote video telemetry system of its type. The HVO-RVTS-1 is significantly more advanced than slow-scan video telemetry developed by USGS for monitoring Mount St. Helens in 1987 (Furakawa, et al. 1992). Also, this system provides a more robust, portable and low-cost alternative to the closed-circuit, microwave TV system that was successfully used by the USGS at Mount St. Helens in 1980 (Miller and Hoblitt, 1981). There is sufficient information provided herein to reproduce the new system. Detailed instructions on the installation and operation of system components is beyond the scope of this report and the reader is referred to well-written equipment manuals supplied by respective manufacturers. A brief summary of recorded eruptive activity from April through September 1997 is presented to demonstrate the utility and value of the system as an eruption monitoring tool. Finally, suggestions are made for improvements which could lend greater versatility to this prototype system for live volcano monitoring.

Thornber, C.R., Sherrod, D., Heliker, C., Kauahikaua, J., Trusdell, F., Lisowski, M., and Okubo, P., 1997, Kilauea's ongoing eruption: Napau Crater revisited after 14 years [abs.]: Eos, Transactions, American Geophysical Union, v. 78, no. 17, p. S329. [AGU-MSA-GS spring meeting, Baltimore, MD, May 27-30, 1990, Program and abstracts]

The current eruption on Kilauea's east rift zone began on January 3, 1983, when fissures opened in Napau Crater, 12 km downrift from the summit. After six months, the eruption localized at a principal vent, 4.5 km east of Napau, and from 1983 to 1986 was characterized by episodic high-fountaining phases that built the 257-m-high Pu'u 'O'o cone (Episodes 1-47). In 1986, the vent migrated 4 km further downrift to the Kupaianaha vent (Episode 48), and eruptive activity was characterized by continuous low level effusion. In 1991, a short-lived fissure eruption occurred between Kupaianaha and Pu'[u] 'O'o (Episode 49). In 1992, the eruption returned to the flank of Pu'u 'O'o, and since 1993 lava has issued from a vent on the uprift side of the cone (Episodes 50-53). Episode 53 continued through January 29, 1997, with lava flowing through a 10-km-long tube system from Pu'u 'O'o to the ocean.
Episode 54 began at ~0240 hrs on January 30, when a new eruptive fissure opened on the floor of Napau Crater. Seismic tremor near the site of this event was first detected at 1841 hrs on January 29. Eleven minutes later, low-level shallow tremor was detected at Kilauea's summit and was followed at 1930 hrs by the onset of rapid summit deflation. Summit tremor and shallow earthquake swarms intensified at 2015 hrs. During Episode 54, a total of 30 mrad of deflation were recorded by the water-tube tiltmeter at the summit and 0.1 m of summit contraction was measured with EDM and GPS. Leveling across the summit caldera shows subsidence localized within a few kilometers of Halema'uma'u pit crater. Summit tremor, subsidence, and contraction continued until the eruption stopped at 0033 hrs on January 31, after which time, summit tilt reversed with slow inflation accumulated 5 mrad of east-northeasterly tilt and 0.02 m of extension by February 10.
The early east rift zone seismic activity (1845 to 2015 hrs on January 29) may correspond to the timing of a complete drainback of the lava pond within the Pu'u 'O'o crater, followed by collapse of the west side (summit and flank) of the Pu'u 'O'o cone. The Pu'u 'O'o crater floor, previously 60 m below the low point on the rim, dropped over 150 m, to a level ~60 m below the pre-1983 surface and the collapse of the flank generated a debris deposit extending 5 km southeast from the cone. From 0240 hrs to 0630 hrs, on January 30, Fissures A, B and C erupted along a 0.8 km long, N60°E line striking from the center of Napau Crater. Fissure D erupted from 1239 to 1450 hrs, overlapping C and extending another 0.5 km northeastward. Fissure E, less than 100 m in length, opened en echelon and 150 m SE of D and was active from 1639 to 1840 hrs. Fissure F erupted from the west wall of Napau Crater from 2043 hrs until 0033 hrs on January 31.
About 300,000 m3 of lava were erupted from six fissures in the Napau Crater area. Surface cracks indicate 1.8 m of opening of the crater floor. GPS stations located 2 km uprift of the fissures and several kilometers away from the rift zone show 0.3 m of extension across the rift during the event. Chemical analysis of Episode 54 lava samples indicate that two separate and distinct rift-stored magma bodies near Napau Crater supplied lava for the eruption. Both Episode 54 magmas are differentiated relative to the lava erupted at Pu'u 'O'o since late 1983 which has been supplied directly from the summit magma chamber.