Chapter 19 science vocabulary
Tsunami
Large powerful ocean wave generated by the vertical motions of the seafood during an earthquake in shallow water can for huge fast moving breakers exceeding 30m in height that can damage coastal areas
Magnitude
Measure of the energy released during an earth quake which can be described using the Richter scale
Modified mercalli scale
Measures earth quakes intensity on a scale of 1 to 7the greater the number the more damage the earth quake caused
Richter scale
Numerical rating system that used to measure the amount of energy that is real eased during an earthquake
Amplitude
The size of seismic waves an increase of one in the scale represents an increase in amplitude of a factor 10
Seismic wave
The vibrations of the ground during an earthquake
Elastic deformation
Causes material to bend and stretch. Proportional to stress so if stress is reduced or returns to its zero the strain or deformation is reduced or disappears
Strain
Deformation of minerals in response to stress
Stress
Forces per unit area that act on a material compression tension and shear
Fault
Fracture or systems of fractures of earths crust that occurs when stress is applied to quickly or stress is to great can form as a result of horizontal compression ( reverse fault) horizontal shear ( strike slip fault) or horizontal tension ( normal fault)
Seismometer
Instrument used to measure horizontal or vertical motion during a earthquake
Seismic gap
Place along a active fault,that has not experienced a earthquake for a long period of time
Focus
Point of the initial fault strain where an earthquake originates that usually lies at least 7 km beneath earth surface
Epicenter
Point on earths surface above the focus of a earthquake
Plastic deformation
Premanent deformation caused by strain when stress exceeds a certain value
Soil liquefaction
Process associated with seismic vibrations that occur in areas of sand that is nearly saturated resulting in the ground behaving like a liquid
Seismogram
Record produced by by a seismometer that can to provide individual tracking of each type of seismic wave
Moment magnitude scale
Scale used to measure earth quake 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 by the size of several types of seismic waves
Secondary wave
Seismic wave that causes rock particles to move at right angles to the direction of the wave known as a S wave
Primary wave
Seismic wave that squeezes and pushes rock in the same direction that the wave travels known as a p wave