06 Earthquakes and Seismic Hazards Free Online FlashCards

How do normal, reverse, and strike-slip faults differ?

Normal faults form as rocks are pulled apart, reverse faults as they are compressed, and strike-slip faults as blocks slide horizontally past one another.

What is elastic rebound in an earthquake?

Elastic rebound is the partial springing back of rock after stress overcomes friction and a fault slips, releasing energy as seismic waves.

How do an earthquake’s focus and epicenter differ?

The focus is where rupture begins inside Earth; the epicenter is the point on the surface directly above it.

What is distinctive about P waves?

P waves are compressional waves: particles move back and forth in the direction the wave travels. They are the fastest seismic waves and travel through solids and liquids.

How do scientists locate an earthquake’s epicenter using seismic waves?

Scientists compare distance estimates from several seismometer stations to locate an earthquake’s epicenter.

How do earthquake magnitude and intensity differ?

Magnitude describes an earthquake’s size at its source; intensity describes shaking and effects at a particular place.

What changes with a one-unit increase in earthquake magnitude?

An increase of one whole magnitude unit corresponds to ten times the measured wave amplitude and roughly 32 times the energy release.

What causes liquefaction during an earthquake?

Liquefaction occurs when loose, water-saturated sediment temporarily loses strength during shaking, which can make buildings settle or tilt.

What should you do indoors during earthquake shaking?

Drop to your hands and knees, cover your head and neck under sturdy cover if possible, and hold on until the shaking stops.

Name ways communities can reduce earthquake risk.

Communities can reduce risk by using hazard maps and land-use planning, enforcing seismic building codes, and retrofitting vulnerable buildings and infrastructure.

How do S waves move, and what can they travel through?

S waves move material perpendicular to their direction of travel. They pass through solids, but not liquids.

What are surface waves, and what shaking can they cause?

Surface waves travel along Earth’s surface after body waves pass through Earth; they often cause strong, prolonged shaking.