Part 3 Seismology for Test 2

These flashcards cover key concepts related to earthquakes, including their causes, measurement scales, and effects.

Seismograph

A machine that records the waves produced by seismic events like earthquakes.

P wave

The fastest seismic wave, which compresses and expands the ground as it travels.

S wave

A type of seismic wave that moves the ground up and down or side to side; slower than P waves.

Surface waves

Seismic waves that travel along the Earth's surface and arrive last during an earthquake.

Fault

A fracture in the Earth's crust along which movement has occurred.

Convergent boundary

A type of tectonic boundary where two plates collide, often causing earthquakes and mountain formation.

Liquefaction

A phenomenon that occurs when saturated soil significantly loses strength and stiffness in response to an applied stress, often during an earthquake. Loose, weak, sediments/ soils start moving

Moment magnitude scale

A more accurate measurement of earthquake magnitude that considers the area of the fault that slipped, the average slip along the fault, and the rigidity of the rocks. Can measure megathrusts and is now the preferred scale for large earthquakes.

Richter scale

An outdated scale for measuring the magnitude of earthquakes based on the amplitude of seismic waves. Cannot measure megathrusts

Megathrust earthquake

A large subduction zone earthquake that occurs at convergent plate boundaries and can generate tsunamis.

Earthquake destruction

ground shaking + acceleration, liquefaction, fire, landslides, tsunamis

Ground shaking + acceleration

more shaking: soft, loose, weak saturated Mud and sand valleys, denser rock less shaking; strong, hard bedrock (igneous+metamorphic, mountains)

Fire

after quakes usually erupt (broken gas lines, broken pipes)

Landslides

loose sediment that failed

Tsunami

post mega thrust quakes

Chile 1960

M=9.5 largest ever recorded, long duration, high recurrence interval, moment scale, areal extent=very large, mega thrust subduction quake

Sumatra 2004

#2 M=9.2 long duration, high recurrence interval, moment scale, large areal extent

Alaska 1964

M=9.2, moment scale, high recurrence interval, long duration, large areal extent, mega thrust subduction quake