5 Earthquakes and Seismic Hazards Free Online FlashCards

What is a fault in the context of earthquakes?

A fault is a fracture in rock where sudden slip can release energy and cause an earthquake.

How do P waves move, and when do they arrive?

P waves compress and expand material in the direction they travel. They are the fastest seismic waves and arrive first.

How do a seismometer and a seismogram differ?

A seismometer detects ground motion; a seismogram is the recording it produces.

What is liquefaction during an earthquake?

Liquefaction occurs when strong shaking makes some water-saturated, loose sediments temporarily lose strength, causing settlement or ground movement.

How do earthquake hazard and risk differ?

Hazard is the potential for damaging shaking or related effects; risk concerns the expected harm to people and property, which increases when exposure or vulnerability is greater.

What should you do during shaking using Drop, Cover, and Hold On?

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

What is an earthquake’s focus?

The focus, or hypocenter, is the underground point where an earthquake rupture begins.

What is an earthquake’s epicenter?

The epicenter is the point on Earth’s surface directly above the earthquake’s focus.

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

S waves move material perpendicular to their direction of travel. They travel through solids, not liquids, and arrive after P waves.

Why can surface waves be especially damaging?

Surface waves move along or near Earth’s surface and often produce strong, damaging ground motion.

How do seismic-wave arrival times help locate an earthquake?

The time difference between P-wave and S-wave arrivals helps estimate a station’s distance from the earthquake source; readings from multiple stations narrow down its location.

How do earthquake magnitude and intensity differ?

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