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What are earthquakes?
Vibrations of the Earth caused by the rapid release of energy
Where do earthquakes occur and how often?
80% of earthquakes occur along the Pacific Rim bc all of the plate boundaries are around the rim.
What are the 4 plate boundaries?
- 1.Convergent plate boundaries
- 2.Divergent plate boundaries
- 3.Transform plate boundaries
- 4.Intraplate earthquakes
What is focus?
Point of origin of the energy release, usually less then 100km deep
What is epicenter?
The spot on the surface of the earth directly above the focus
When do earthquakes occur?
When built up pressure is suddenly released
What is the elastic rebound theory?
- -explains how energy is stored in rocks
- -rocks bend until the strength of the rock is exceeded
- -rupture or breakage occurs and the rocks quickly rebound to an undeformed shape
- -energy is released in waves
What is the sequence of Earthquake generation?
- 1.Foreshock-small,creep- happens before earthquake occurs
- 2.Main Earthquake
- 3.Aftershock-smaller, numerous earthquakes that can continue for up to 1-2yrs
What does seismo mean?
study of vibrations or earthquakes
What is seismology?
The study of earthquakes
What is a seismograph (seismometer)?
A machine that records the seismic waves
What is a seismogram?
The actual record of the seismic waves
What are the two types of Seimic Waves?
- 1.Body Waves
- 2.Surface Waves
What are body waves?
Waves that travel through the body of the earth
What are the two types of body waves?
- 1.P or primary waves-fastest 6-7km/s, compressional waves, travel through solids, liquids, and gases
- 2.S or secondary waves-slower 3.5km/s, only travel through solids
What are the two types of surface waves?
- 1.L or Love waves-side to side
- 2.R or Rayleigh waves-up down
- L and R waves are the slowest type of waves 2.5km/s, travel only through solids, very close to epicenter.
- *These waves cause the most damage during earthquakes*