Volcanoes

When Mt. St. Helens erupted in May of 1980, ash blew as far away as ________.

• Oklahoma

• Texas

• New Jersey

• New Hampshire

If you had to live on an active volcano, which of the following would you choose if safety was your only concern?

• Mount Fujiyama in Japan

• Mount Mauna Loa in Hawaii

• Mount Rainier in Washington

• Mount Spurr in the Aleutian volcanic arc in Alaska

________ is the major dissolved volatile constituent in both magmas and volcanic gases.

• Calcium Carbonate

• Water

• Carbon Monoxide

• Methane

Which of the following factors help determine whether a volcanic eruption will be violent or relatively quiescent (smooth flowing)?

• temperature of the magma

• Composition of the magma

• amount of dissolved gas in the magma

• all the above

________ tend to increase the explosive potential of a magma body beneath a volcano.

• high viscosity and high dissolved gas content

• low silica content and low viscosity

• low viscosity and low dissolved gas content

• high viscosity and low dissolved gas content

Which magma type has the lowest viscosity?

• pumice

• granite

• basalt

• adesite

What type of volcanic material is indicative of eruption under water?

• pillow basalt

• basalt apron

• pyroclastic flow

• Aa

Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface?

• Aa

• Pahoehoe

• pegmatitic

• scoria

Volcanic bombs originate ________.

• as erupted magma blobs that partly congeal before falling to the ground in the shape of lemons or footballs

• as ash particles that join together in the eruptive plume and fall as cobble-sized objects

• as blocks of volcanic rock ejected from an erupting volcanic crater

• as enormous blocks launched in a solid form from a volcanic plug

________ magma is the most abundant type of magma erupted on Earth.

• Andesitic

• Pegmatitic

• Granitic

• Basaltic