Volcanoes in Eruption - Set 2
Entry ID:
gov.noaa.ngdc.G01223
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Summary
ABSTRACT: The word volcano is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain built up around the opening by the eruptive products. This slide set depicts ash clouds, fire fountains, lava flows, spatter cones, glowing avalanches, and steam eruptions from 18 volcanoes in 13 countries. Volcano ... types include strato, cinder cone, basaltic shield, complex, and island-forming. Perhaps no force of nature arouses more awe and wonder than that of a volcanic eruption. Volcanoes can be ruthless destroyers. Primitive people offered sacrifices to stem the tide of such eruptions and many of their legends were centered around volcanic activity. Volcanoes are also benefactors. Volcanic processes have liberated gases of the atmosphere and water in our lakes and oceans from the rocks deep beneath Earth's surface. The fertility of the soil is greatly enhanced by volcanic eruptive products. Land masses
such as islands and large sections of continents may owe their existence entirely to volcanic activity. The "volcano" is used to refer to the opening from which molten rock and gas issue from Earth's
interior onto the surface, and also to the cone, hill, or mountain built up around the opening by the eruptive products. The molten rock material generated within Earth that feeds volcanoes is called magma and the storage reservoir near the surface is called the magmachamber. Eruptive products include lava (fluid rock material) and pyroclastics or tephra (fragmentary solid or liquid rock material). Tephra includes volcanic ash, lapilli (fragments between 2 and 64 mm), blocks, and bombs. Low viscosity lava can spread great distances from the vent. Higher viscosity produces thicker lava flows that cover less area. Lava may formlava lakes of fluid rock in summit craters or in pit craters on the flanks of shield volcanoes. When the lava issues vertically from a central vent or a fissure in a
rhythmic, jet-like eruption, it produces a lava fountain. Pyroclastic (fire-broken) rocks and rock fragments are products of explosive eruptions. These may be ejected more or less vertically, then
fall back to Earth in the form of ash fall deposits. Pyroclastic flows result when the eruptive
fragments follow the contours of the volcano and surrounding terrain. They are of three main types: glowing ash clouds, ash flows, and mudflows. A glowing ash cloud (nuee ardente) consists of an avalanche of incandescent volcanic fragments suspended on a cushion of air or expanding volcanic
gas. This cloud forms from the collapse of a vertical ash eruption, from a directed blast, or is the
result of the disintegration of a lava dome. Temperatures in the glowing cloud can reach 1,000
deg C and velocities of 150 km per hour. Ash flows resemble glowing ash clouds; however, their temperatures are much lower. Mudflows (lahars) consist of solid volcanic rock fragments held in
water suspension. Some may be hot, but most occur as cold flows. They may reach speeds of 92
km per hour and extend to distances of several tens of kilometers. Large snow-covered volcanoes
that erupt explosively are the principal sources of mud flows. Explosions can give rise to air shock waves and base surges. Air shock waves are generated as a result of the explosive introduction of volcanic ejecta into the atmosphere. A base surge may carry air, water, and solid debris outward from the volcano at the base of the vertical explosion column. Volcanic structures can take many forms.
A few of the smaller structures built directly around vents include cinder, spatter, and lava cones.
Thick lavas may pile up over their vents to form lava domes. Larger structures produced by low viscosity lava flows include lava plains and gently sloping cones known as a shield volcanoes. A stratovolcano (also known as a composite volcano) is built of successive layers of ash and lava. A volcano may consist of two or more cones side by side and is referred to as compound or complex. Sometimes a violent eruption will partially empty the underground reservoir of magma. The roof of
the magma chamber may thenpartially or totally collapse. The resulting caldera may be filled by
water. The volcanic structure tells us much about the nature of the eruptions.
PURPOSE: Make available Damage Photos for research and education
CURRENTNESS REFERENCE: Publication Date
Fees: $25.00 plus handling and shipping outside the USA Free download $195.00/145.00 plus handling and shipping outside the USA
Geographic Coverage
Spatial coordinates
| N: 63.3 |
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S: -39.16 |
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E: 175.63 |
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W: -159.38 |
Data Set Citation
Dataset Creator:
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce (comp)
Dataset Title:
Volcanoes in Eruption - Set 2
Dataset Release Date:
1994
Dataset Release Place:
Boulder, CO
Dataset Publisher:
National Geophysical Data Center
Version:
First
Online Resource:
http://www.ngdc.noaa.gov/hazard/
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Temporal Coverage
Start Date:
1866-01-01
Stop Date:
1986-03-31
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Location Keywords
Science Keywords
ISO Topic Category
Project
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ACCESS CONSTRAINTS: None
DISTRIBUTION LIABILITY: While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
CUSTOM ORDER PROCESS: Contact Data Center
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None
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Distribution
Distribution Size:
20412.0
Distribution Format:
TIFF
Fees:
Please See Summary
Distribution Format:
TIFF
Fees:
Please See Summary
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Personnel
JOY
IKELMAN
Role:
TECHNICAL CONTACT
Phone:
303-497-6419
Fax:
303-497-6513
Email:
Joy.A.Ikelman at noaa.gov
Contact Address:
NOAA/NESDIS/NGDC
Mail Code E/GC4
325 Broadway
City:
Boulder
Province or State:
CO
Postal Code:
80303
Country:
USA
KELLY
STROKER
Role:
DIF AUTHOR
Phone:
(303) 497-4603
Fax:
(303) 497-6513
Email:
kelly.stroker at noaa.gov
Contact Address:
NOAA/NESDIS/NGDC E/GC1 325 Broadway
City:
Boulder
Province or State:
CO
Postal Code:
80305-3328
Country:
USA
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Related URL
Link:
GET DATA
Description:
View all the slides in this slide set
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Creation and Review Dates
DIF Creation Date:
2008-01-28
Last DIF Revision Date:
2008-04-14
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Links
