EAS Exam 2 Question Bank

Which eruption style is characterized by short lived explosive bursts driven by bursting gas bubbles within magma?

Strombolian

Which eruption type does NOT involve new magma?

Phreatic

Which volcanic product travels as a fast moving mass of hot gas and volcanic matter at ~100 km/h?

Pyroclastic Flow

Which volcanic gas is most abundant in magma?

H2O

Which characteristic best describes mafic magma?

Hotter and flows easily

Which eruption type is associated with huge eruption columns reaching into the stratosphere?

Plinian

The Toba eruption (~74,000 years ago) is classified as

VEI 8

Which of the following settings is typically associated with mantle origin magmas?

Hot spots and divergent boundaries

The geothermal gradient alone is sufficient to melt rocks in the lower crust and upper mantle.

false

A decrease in confining pressure can cause decompression melting

true

Felsic magma tends to contain more water and gas than mafic magma

true

Shield volcanoes are typically formed by successive basalt lava flows

true

Pyroclastic flows are slower than most lava flows

false

The lateral blast at Mt. St. Helens (1980) removed over 300 meters from the summit

True

Volcanic aerosols can reach 20 to 25 km altitude and affect global climate.

True