Study Guide for Test 3: Natural Disasters (Geol 1151)

Flashcards covering key concepts related to volcanic eruptions, magma types, volcanic landforms, and case studies of notable volcanic events.

Plate margins

Areas where most volcanic eruptions occur, including divergent, convergent/subduction, and transform boundaries.

Divergent margin

A plate boundary where seafloor spreading occurs, characterized by the extruding of high volumes of basaltic magma.

Viscosity

A measure of a fluid's resistance to flow; lower viscosity results in more effusive eruptions, while higher viscosity can lead to explosive eruptions.

Volcanic Explosivity Index (VEI)

A scale that measures the size of volcanic eruptions from 0 to 8, indicating the explosiveness of an event.

Shield volcano

A type of volcano with low viscosity basaltic lava, resulting in broad, gentle slopes, like those found in Hawaii.

Caldera

A large depression formed when a volcano's magma chamber empties and the land above collapses, potentially causing tsunamis.

Pyroclastic flow

A fast-moving current of hot gas and volcanic matter that flows down the sides of a volcano during an explosive eruption.

Lahar

A destructive mudflow on the slopes of a volcano, typically triggered by volcanic activity and often causing fatalities and damage.

Cascade Range volcanoes

Volcanoes located in the Pacific Northwest of the U.S., notably Mount St. Helens and Mount Hood, known for their activity over the past 4,000 years.

Carbon dioxide (CO2) leak

A dangerous phenomenon where CO2 accumulates beneath a lake, leading to asphyxiation of nearby life, as seen in Lake Nyos in Cameroon.