Seismology (Earthquakes)

Front 1

Definition and Cause of Earthquakes

Back 1

Def: a release of energy in the crust; explained by the Elastic Rebound Theory
Cause: meteor impact, train, movement of lithospheric plates

Front 2

Focus:
Shallow
Intermediate
Deep

Back 2

The point where seismic energy (waves) originate
S: 0-70km; found @ convergent boundaries
I: 70-300km; found @ divergent boundaries
D: 300-700km; found @ divergent boundaries

Front 3

Fault

Back 3

Any fracture in the Earth's crust where movement occurs; faults can be plate boundaries

Front 4

Epicenter

Back 4

Point on the Earth's surface about the focus

Front 5

Seismic Waves
Primary

Back 5

Travel as compressional energy (push-pull); fastest traveling seismic wave able to travel through all mediums

Front 6

Seismic Waves
Secondary

Back 6

Travel as shear energy (side to side); slower than P waves and only able to travel in SOLIDS; affected particles move at right angles to the direction of the wave

Front 7

Seismic Waves
Longitudinal

Back 7

Last seismic wave to arrive; a local product of the P and S waves; affected particles move in a circular motion as the wave passes--CAUSE THE MOST DESTRUCTION

Front 8

All seismic waves increase their speed and strength as the rock they trave through...

Back 8

...increases in density and rigidity

Front 9

Earthquake Magnitudes (based on logarithms)
Mercalli Scale

Back 9

Based on ground shaking and foundation failure

Front 10

Earthquake Magnitudes (based on logarithms)
Richter Scale

Back 10

Every increase of 1 on the scale translates into an increase of 32 in seismic wave energy (For example: an earthquake with a magnitude of 5.5 is 32 timres stronger that an earthquake of magnitude 4.5)

Front 11

Earthquake Magnitudes (based on logarithms)
Seismic Moment Scale

Back 11

Not as easy to measure, but it does give an accurate indicator of the total energy released in an earthquake (not just wave energy)

Front 12

Earthquake Prediction:
P-wave velocities increase before a major quake...why?

Back 12

Here's why...

Front 13

Earthquake Prediction:
Elevation changes can be detected and measured before a major tremor...why?

Back 13

Here's why...

Front 14

Earthquake Prediction:
Radon gas in well water...

Back 14

...increases before a major quake

Front 15

Earthquake Prediction:
Lasers are used to detect motion along active faults--If there is no motion...

Back 15

...there is

Front 16

Earthquake Prediction:
Seismic Gap Method

Back 16

Uses known periods of time between quakes as an indicator; this method is based on past quake patterns and power laws