Seismic Waves and Inversion

[attachment=16125]


What are Seismic Waves ???

1 Seismic waves are the vibrations from earthquakes that travel through the Earth

2 They are the waves of energy suddenly created by the breaking up of rock within the earth or an explosion .They are the energy that travels through the earth and is recorded on seismographs


History Cont

1 Around 132 AD, Chinese scientist Chang Heng invented the first seismoscope, an instrument that could register the occurrence of an earthquake.

2 They are recorded on instruments called seismographs. Seismographs record a zigzag trace that shows the varying amplitude of ground oscillations beneath the instrument. Sensitive seismographs, which greatly magnify these ground motions, can detect strong earthquakes from sources anywhere in the world. The time, location and magnitude of an earthquake can be determined from the data recorded by seismograph stations.

Types of Seismic Waves 

Body waves 
Travel through the earth's interior

Surface Waves
Travel along the earth's surface - similar to ocean waves

Secondary Wave 

Secondary or shear (S) waves
a)The second type of body wave is the S wave or secondary wave, which is the second wave you feel in an earthquake.

b) An S wave is slower than a P wave and can only move through solid rock. (3.6 km/sec in the crust)

c) This wave moves rock up and down, or side-to-side.