Deck 1: Earthquakes and Seismic Waves

What causes earthquakes in the brittle lithosphere?

Movement along faults

Which seismic wave travels through solids, liquids, and gases?

Primary (P) waves

Which seismic wave only travels through solids?

Secondary (S) waves

Which seismic wave causes the most destruction?

Surface waves

What is the focus of an earthquake?

The point inside Earth where rupture begins

What is the epicenter?

The point on Earth’s surface directly above the focus

What instrument records seismic waves?

Seismograph

What scale measures earthquake magnitude?

Richter scale (or Moment Magnitude)

What scale measures earthquake damage? 

Modified Mercalli Intensity scale

What is elastic rebound theory?

Rocks store energy until they break, releasing it as an earthquake

What is aftershock?

Smaller earthquake following the main shock

What is foreshock?

Smaller quake occurring before the main event

What is seismic gap theory?

Areas with little recent activity may be due for a large quake

What is liquefaction?

Saturated sediments lose strength and behave like a fluid during shaking.

Why are threshold slopes (>25) dangerous?

They are prone to landslides

What is a tsunami?

a large ocean wave generated by undersea earthquakes or landslides

What secondary hazard often follows large earthquakes near coasts?

tsunami

what is a seismic risk?

probability of earthquake damage in a region