Earthquakes Study Guide
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Earthquakes Study Guide
Deformation is the change in the shape of rock in response to stresses placed on it.
Plastic deformation results in folding.
Elastic deformation leads to earthquakes.
An earthquake is the shaking of the Earth’s lithosphere that is caused by the energy released when rock breaks.
Most earthquakes occur along plate boundaries.
Focus: the point along a fault at which the first motion of an earthquake begins
Epicenter: the point on Earth’s surface directly above the earthquake’s starting point, or focus
You need 3seismograph readings to triangulate the location of an epicenter
The simplest method used to find the epicenter of an earthquake is the S-P method (S wave arrival time minus P wave arrival time).
Seismic waves: a wave of energy that travels through the Earth, away from an earthquake in all directions
Body waves
- P waves, also know as primary waves, or pressure waves
- Can travel through solids and liquids
- Are the fastest and first to arrive at a seismograph
- Cause particles of rock to move in a back and forth motion like an accordion
- S waves, also known as secondary waves, or shear waves
- Can only travel through solids
- Are slower than p waves
- Cause particles of rock to move in a side to side direction
Surface waves
- Move along the Earth’s surface
- Slowest moving seismic waves
- Cause the most destruction
A seismograph is an instrument that records vibrations in the ground and determines the location and strength of an earthquake
A seismogram is a tracing of earthquake motion that is created by a seismograph
Richter magnitude scale: measures the strength of an earthquake by measuring ground motion recorded on seismographs
Uses Arabic numbers
Each time the magnitude increases by 1 unit the ground motion becomes 10 times larger
Modified Mercalli Intensity Scale: measures the degree to which an earthquake is felt by people and the amount of damage caused
Uses Roman numerals
Intensity can vary from place to place
Earthquake Quiz Study Guide created 7 June 2012 by B. Ferri – edited 12 December 2016