| A | B |
|---|
| fracture | the ability of a mineral to break into pieces with arc-like, rough, or jagged edges |
| stress | forces per unit area that act on a material, such as tension, compression, and shear |
| strain | deformation of materials in response to stress |
| elastic strain | low stress deformation that causes material to bend and stre |
| ductile deformation | when stress exceeds a given value and causes permanent deformation |
| fault | fracture in Earth's crust that occurs when stress is applied too quickly or stress is too great |
| seismic wave | the vibrations of the ground during an earthquake |
| primary wave | seismic wave that squeezes and pulls rock in the same direction that the wave travels, causing rock particles to move back and forth |
| seconary wave | seismic wave that causes rock particles to move at right angles to the direction of the wave |
| focus | point of the initial fault rupture where an earthquake originates; usually lies at least several kilometers beneath Earth's surface |
| epicenter | point on Earth's surface directly above the focus of an earthquake |
| lithosphere | Earth's rigid outer shell, including the crust and the solid, upper most part of the mantle |
| seismometer | an instrument that can detect earthquake vibrations from great distances |
| seismogram | the record produced by a seismometer |
| encounter | to come upon or experience, especially unexpectedly |
| magnitude | the amount of energy released during an earthquake |
| amplitude | the size of a seismic wave |
| Richter Scale | based on the largest seismic waves made by an earthquake |
| moment magnitude scale | accounts for the magnitude, size of the fault rupture, amount of movement along the fault, and the rocks' stiffness |
| modified Mercalli scale | measures the amount of damage from an earthquake |
| landslide | rapid downslope movement of a mass of loose soil, rock, or debris that has separated from the bedrock |
| tsunami | large, powerful, ocean wave generated by the vertical motions of the seafloor during an earthquake |
| soil lithification | soil-saturated land behaves like a fluid |
| seismic gap | place along an active fault that has not experienced an earthquake for a long time |
