Department of Biological Sciences and Geology


Materials extruded during a volcanic eruption include:

Types of Volcanoes

Distribution of Volcanic Activity


1) pyroclastic debris can cover a landscape, kill crops and animals, collapse roofs, and even obscure sunlight. Even small volcanoes can cover large areas with ash; for instance, Mt. St. Helens erutpion of 1980 spewed ash as far east as Oklahoma. Nuees Ardentes (fiery clouds of superhot poison gas and ash moving up to 100 MPH) can kill everything in their path.

Volcanic Hazards, visit ash fall zone for Mt. St. Helens, 1980

2) volcanic emissions of gases can cause acid rain; aerosols released such as SO2 coupled with fine ash in the upper atmosphere can block and reflect sunlight back into space and cause global cooling, for instance the year without summer caused by the Mt. Tamora's eruption of 1815 (see p. 85)

3) Lahars (a Polynesian word for mudflows) can kill people and destroy property and move at suprisingly rapid speeds, up to 60 MPH

4) Eruptions can trigger seismic sea waves, TSUNAMI, that can race across vast oceans (at speeds close to that of a jet airliner) and then rise with little warning to break along the shore. Waves of close to a hundred feet are known. While in the deep ocean these waves are barely detectable, when the waves get into shallow water and crest there is no time left to evacuate. The eruption of Krakatau in 1883 generated tsunamis that were responsible for most of the deaths caused by the eruption. 36,000 people died.

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Suggested Sites to Visit

Ashfall Fossil Beds State Park
USGS Volcanic Hazards Program
Volcano World
Virtually Hawaii
Michigan Technological University Volcanoes Page
LANL-UNM Volcanology Program
Global Volcanism Program, Smithsonian Institution
World-Wide Volcanism, NASA
Satellite Images, NASA (includes volcanos)
Views of the Solar System, Terrestrial Volcanism
The Electric Volcano--Dartmouth College's Volcanic-information
Volcano Information Center
Volcano Information, USGS
Hawaiian Volcano Observatory
Hawaiian Center for Volcanology
JASON Project VI: Island Earth
Cascades Volcano Observatory, USGS
Mount St. Helens, Washington, USGS
Nordic Volcanological Institute, Iceland
Volcanism on the Moon
Volcanism on Io, Jupiter's moon
Volcanic Jump Station, List of web pages with Volcanos
Worldwide Weather
BBC News, Super Volcanoes