Natural Disasters Midterm

Natural Disasters Midterm Study Guide

What is the key evidence supporting Wagner’s continental drift hypothesis?

The shapes of continents fit together like a puzzle, matching rock sequences and fossil distributions, and glacial evidence in tropical areas.

What are the pieces of evidence that support plate tectonics/seafloor spreading? Name all six.

(1) Seafloor Topography, (2) Age of the Seafloor, (3) Heat Flow, (4) Volcanoes, (5) Earthquakes, (6) Paleomagnetism.

What is the lithosphere?

The crust and very upper mantle where tectonic plates exist.

What defines the asthenosphere?

A layer below the lithosphere that consists of partially melted minerals allowing for the movement of tectonic plates.

What happens at a divergent boundary?

Tectonic plates move apart, creating new crust as magma rises, forming mid-ocean ridges.

What types of volcanic eruptions are characterized by low-viscosity magma?

Mild eruptions, typical for basaltic magma.

What conditions lead to explosive volcanic eruptions?

High-viscosity magma that traps gases leads to explosive eruptions.

What are some hazards associated with earthquakes?

Ground shaking, aftershocks, landslides, elevation changes, liquefaction, and tsunamis.

What is the focus of an earthquake?

The exact point inside the Earth where the earthquake begins.

What is the epicenter of an earthquake?

The point on the Earth's surface directly above the focus.

What types of seismic waves are there?

P waves, S waves, Rayleigh waves, and Love waves.

What is the Moment Magnitude Scale (MMS)?

A scale that measures the total energy released by an earthquake based on seismic wave amplitude.

What does the Modified Mercalli Intensity Scale measure?

The effects of the earthquake on people, buildings, and the Earth's surface.

What kind of volcano is formed from low-viscosity basaltic magma?

Shield volcanoes.

What features characterize stratovolcanoes?

Steeper slopes and composed of andesitic and rhyolitic magma.

What is the Volcanic Explosivity Index (VEI)?

A scale that classifies volcanic eruptions based on their explosiveness and volume.

How does a tsunami form?

A sudden vertical displacement of the ocean floor caused by underwater earthquakes, landslides, or volcanic eruptions.

What indicates a potential tsunami?

A rapid change in sea level, such as a sudden rise or retreat of the ocean.

What type of avalanche is typically more deadly?

Dry avalanches, as they are faster and more forceful.

What are the two primary triggers of mass wasting?

Increase in water content and seismic shaking.

What type of weathering involves the breakdown of rocks without changing their chemical composition?

Physical weathering.

What happens to a slope when water content increases?

It can weaken the material on the slope and increase erosion risk.

What are the three categories of motion during a slope failure?

Fall, Slide, and Flow.