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ES Chapter 19 Vocab
Chapter 19 vocab
Question | Answer |
---|---|
stress | forces per unit area that act on a material compression tension and shear |
strain | deformation of materials in response to stress |
elastic deformation | causes materials to bend and stretch proportional to stress so if the stress is reduced or returns to zero the strain or deformation is reduced or disappears |
plastic deformation | premanent deformation caused by strain when stress exceeds a certain value |
fault | fracture of system of fractures in Earth's crust that occurs when stress is applied too quickly or stress is too great can form as a result of horizontal compression horizontal shear or horizontal tension |
seismic wave | the vibrations of the ground during an earthquake |
primary wave | seismic wave that squeezes and pushes rocks in the same direction that the wave travles known as a P wave |
secondary wave | seismic wave that causes rock particles to move at right angles to the direction of the wave known as S wave |
focus | point at the initial fault rupture where an earthquake originates that usually lies at least several kilometers beneath earth's surface |
epicenter | point on earth's surface directly above the focus of an earthquake |
seismometer | instrument used to measure horizontal or vertical motion during an earthquake |
seismogram | record produced by a seismometer that can provide individual tracking of each type of seismic wave |
richter scale | numerical rating system used to measure the amount of energy released during an earthquake |
magnitude | measure of the energy released during an earthquake which can be described using the richter scale |
amplitude | the size of the seismic waves an increase of 1 in the scale represent an increase in amplitude of a factor of 10 |
moment magnitude scale | scale used to measure earthquake magnitude taking into account the size of the fault rupture the rocks stiffness and amount of movement along the fault using values that can be estimated from the size of several types of seismic waves |
modified Mercalli scale | measures earthquake intensity on a scale from I to XII the higher the number the greater the damage the earthquake has caused |
soil liquefaction | process associated with seismic vibration that occur in areas of sand that is nearly saturated resulting in the ground behaving like a liquid |
tsunami | large powerful ocean wave generated by the vertical motions of the seafloor during an earthquake in shallow water can form huge fast moving breakers exceeding 30 m in height can damage coastal areas |
seismic gap | place along an active fault that has not experienced an earthquake for a long time |