a break in the earth's crust aong which the earth's crust slides relative to other rocks.
the change in the shape of rock in response to stress
1) plastic deformation: like clay (doesn't lead to earthquakes)
2) elastic deformation: like a rubber band; rocks stretches and eventually breaks due to the realease of energy
the sudden return of elastically deformed rock to its original shape (stress is applied to rock, energy is released as seismic waves,causes an earthquake)
a)strike-slip fault (crust slides horizantally)
b)reverse fault (rocks are pushed together)
c) nromal fault (rocks pull away)
waves of energy that travel through the earth
1) p waves
-waves that travel trough solids, liquids and gasses
- pressure waves and primary waves
-fastest waves and are always the first to be detected
-creates a movement that makes rock move side to side. (stretch the rock sideways) It then springs back to its original position.
-cannot travel through any liquid
- shear waves or secondary waves
-move along the surface of the earth
-types; one produces a motion of up, down, and around whil the other typeproduces back and forth motion
-surface waves are slower, but cause more destruction
elastic rebound- sudden return ofelastically deformed rock to its original shape
A seismogram is a tracing of an earthquake motion and is created by a seismograph. A seismograph is an instrument that is located at the surface of the earth and they record seismic waves.
the point on the earth's surface above an earthquakes starting point, or focus.
the point along afault at which the first motion of an eartquake occurs
It is used to find an earthquake's epicenter. while doing this, it also colleects information on how fast the P and S waves are moving and the distance between them.
seismograph station, epicenter
in one, earthquake's epicenter
-used to measure the strength of an earthquake
-compare earthquakes by measuring ground motion recorded by seimographs and seismograms
the measure of strenth in an earthquake
-a measure of degree to which an earthquake that is felt by people and the amount of damage caused by the earthquake
-intensity values are usually higher near the earthquake's epicenter
-a measurement of how likely an area is to have damaging earthqakes in the future
-determined by past and present seismic activity
The strength of an earthquake is related to how often they occur. Also, by just a decrease in the magnitude of an earthquake, the number of earthquakes occuring will increase by about 10 times.
8.0 or higher with a frequency of one earthquake
The Mercallli system records the damage done after an earthquake (or the intensity) while the Richter Magnitude Scale mostly measures the strength if the earthquake. It compares earthquakes by measuring the ground motion. The Mercalli record the ending results, or the aftermath.
-hypothesis that is based on the idea that a major earthquake is more liikely to occur along the part of an active fault where no earthquakes have occured for a certain period of time
-an area along a fault where relatively few earthquakes have occured recently but where string earthquakes have occured in the past