Earthquakes

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earthquake

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a sudden movement of Earth's crust that releases energy

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mountains

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regions of higher relief relative to the surroundig landscape

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ways mountans form

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folded mts
fault block mts
volcano mts

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folded mts

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folds that are compressed by converging forces may be flexible enough to fold and not break

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fault block mts

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if a plate undergoes compression (convergence) and the rocks are brittle or it undergoes stress (divergent) then the rocks may crack and create faults

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fault block mts

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if there is vertical movement along these faults, mts may form

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normal faults

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the hanging wall moves down relative to the foot wal (divergent - tension)

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reverse faults

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the hanging wall moves up in relation to the foot wall (convergent -compression)

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transform faults (sheer)

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only horizontal movements are noticeable

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principle of original horizontality

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sediments are deposited in horizontal layers that are parallel to the surface at the line of deposition

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earthquakes

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a shaking of the earth's crust due to a release of energy

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seismology

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the study of earthquakes

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internal forces of earthquakes -
stress-

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a slow bonding force that eventually breaks rocks

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internal forces of earthquakes - strain -

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causes the break along a fault

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faults

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cracks along the earth's surface along which movement occurs

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parts of a fault -
focus -

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the actual location within the earth where an earthquake occurs

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epicenter

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the location in Earth's surface directly above the focus of an earthquake

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fault or sa

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the crack (fracture) along the surface where movement along a fault is noticeable

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strongest earthquakes occur -

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along transfom and convergent plate boundaries

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seismic waves

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vibrations of energy that are released by an earthquake

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common causes of earthquakes

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1.volcanic eruptions
2.collapse of caverns
3.meteor impacts
4. release of built up stress between the lithospheric plates moving past one another

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common effects of earthquakes
-short term -

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collapse of buildings, explosions, broken electric wires or gas mains, sewage line breakages, tsunamis

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long term effects of earthquakes

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spread of disease, food shortages, railways and airport closures,

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how do earthquake waves travel?

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earthquakes release their energy in the form of waves

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3 basic types of waves

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1. primary (compressional) waves
first to arrive (P waves)

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3 types of waves

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2. secondary (longitudinal ) waves (S waves)
second to arrive

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3 types of waves

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3. surface (longitudinal) waves
L waves
cause the most damage

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P waves travel....

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twice as fast as s-waves so they arrive at the location first

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seismograph

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measure movements within earth and they are recorded on a seismogram

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locating epicenters
Triangulation-

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the arrival of P and S waves can be used to determine the exact location of an epicenter by using data from 3 seismic stations

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locating epicenters
ESRT (Page 11)

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you can use page 11 to determine the exact time an earthquake occurred

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seismogram

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looking at the seismogram determines when the P-waves arrived, hen the s -waves and then figure out the differences in arrival time between the P and S waves.