Volcanic Hazards

Lecture outline - Answer portion

What are compositional variations and physical properties of lavas?

How do you melt rocks? Three recipes:

What are the sources of magma? Multiple sources, mixing and segregation all play a role.

What are types of volcanic eruptions or phenomenon?

Lahar videos:


Columbia River flood basalts

Map showing the overall extent of the Columbia River Flood basalts. Humans have not witnessed eruptions on this scale. 170,000 cubic kilometers of basalt are included int his province. Image source: http://vulcan.wr.usgs.gov/Volcanoes/ColumbiaPlateau/Maps/map_columbia_plateau.html

Steamboat rock mesa along the Columbia River. The dark layers stacked one on top of each other are individual flows. SImage source: http://3dparks.wr.usgs.gov/grandcoulee/html2/gc711.htm

Figure of Columbia River flood basalts, two thick flows, one stacked on top of the other. Two red lines mark contact between flows. Medium sized trees at base for scale. these basalts represent part of a large igneous province that was emplaced some 16 million years ago. Taken during 1987 field trip.


What is determining these two different types of volcanic constructs? Melt viscosity and gas content!

What plate settings do different types of volcanism occur in?

So what's the concern? What should be included in a hazard map for a volcanic region?

Can an eruption be controlled or prevented?


© Harmon D. Maher Jr.. This page may be used for non-profit educational purposes. For any other use please contact me.

H.D. Maher Jr., 3/6/200

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