Earthquake definitions Flashcards
Aftershock
Smaller earthquake that occurs after a large earthquake in the same area
Elastic rebound
Stress of plate movement is stored in the crust until it is suddenly released as an earthquake
Epicentre
Point on the earths surface directly above the focus. Most damage occurs here
Focus
Point underground where an earthquake begins, crust suddenly cracks here
Intensity
The effect of an earthquake on the earth’s surface observed and felt by people where they live. Measured by Modified Mercalli Scale
Liquefication
Sandy soil and sediment turns to liquid when shaken during an earthquake. Water held in pores of the sediment is released as the ground shakes causing buildings and cars to sink into ground. Eg. Christchurch New Zealand 2010
Magnitude
Energy released by an earthquake , measured on Richter Scale
Modified Mercalli Scale
Developed in 1931 by Harry Wood and Frank Neumann. Ranking based on observed effects. Levels of intensity range. I - XII
P Waves
Compressional wave, is an earthquake wave that shakes ground back and forth in same direction as wave is moving
Richter Scale
Charles Richter, 1935. Used to measure energy released
S Waves
Shear wave, an earthquake wave that shakes ground back and forth perpendicular to direction wave is moving
Seismic wave
Pulse of energy generated by an earthquake. Waves may travel along surface or inside earth
Seismograph / seismometer
Instrument used to detect or record earthquakes
Shockwaves
Another word for seismic waves / tremors
Surface waves
These slow waved travel along earth’s surface moving up and down as well as side to side
