Chapter 4 Volcanism Practice Flashcards

This set of flashcards covers key concepts from Chapter 4 on Volcanism, including magma formation, volcano classification, and hazardous volcanic processes.

At divergent boundaries and mantle plumes, magma is primarily formed through __________ melting.

decompression

At convergent boundaries, magma is formed through __________ melting, where water from a subducting plate acts as a flux.

flux

A __________ eruption occurs on the ocean floor or under a lake, while a subaerial eruption occurs on land.

subaqueous

Mount Garibaldi, near Squamish, B.C., last erupted approximately __________ years ago.

$$10,000\,years$$

Felsic magmas tend to have higher levels of volatiles, typically representing __________ to __________ of their weight.

$4\%$ to $7\%$

A volcanic eruption that involves a steady, non-violent flow of magma is described as __________.

effusive

__________ are small, steep-sided volcanoes typically made up of fragments of vesicular mafic rock called scoria.

Cinder cones

The world's largest shield volcano, Mauna Loa, rises __________ above sea level.

$$4,169\,m$$

The cool, ropy texture formed by non-viscous lava flowing gently is called __________.

pahoehoe

Blocky lava that forms when magma is forced to flow faster than it is able to is called __________.

aa

A __________ is a volcanic crater that is more than $2\,km$ in diameter.

caldera

Large igneous provinces (LIP) are associated with enormous bursts of magma from __________ plumes.

super

Kimberlites originate in the mantle at depths ranging from __________ to __________.

$150\,km$ to $450\,km$

Direct volcanic hazards have accounted for fewer than __________ deaths during historical times.

$$200,000$$

A __________ density current is a mixture of hot gases and tephra that can flow down a volcano at hundreds of kilometres per hour.

pyroclastic

A __________ is a mudflow or debris flow related to a volcano, often caused by melting snow and ice.

lahar

In 1985, a massive lahar triggered by the eruption of __________ killed 23,000 people in Armero, Colombia.

Nevado del Ruiz

The most abundant volatile in magma is __________, followed by carbon dioxide ($CO_2$).

water ($H_2O$)

A __________ is a sensitive three-directional level used to sense small changes in ground tilt near a volcano.

tiltmeter

Canada's most recent volcanic eruption occurred approximately $250\,years$ ago at the __________ Cone.

Tseax River