Question | Answer |
Faults | A planar fracture in a volume of rock in which there has been significant displacement. |
Continental Drift | The movement of Earth's continents relative to each other. |
Plate Tectonics | A scientific theory that describes the large scale motions of Earth's Lithosphere. |
Earth's Crust | The outermost solid shell of rocky Earth. |
Foreshocks | A small earthquake precedes a major earthquake or volcanic erruption. |
San Andreas Fault | The boundary between two plates, the North American Plate and the Pacific Plate. |
Elastic Energy | Elastic energy is internal energy that can be converted into mechanical energy under adiabatic conditions. |
Elastic Reboud | The elastic rebound theory is an explanation for how energy is spread during earthquakes. |
Fault Creep | Slow, more or less continuous movement occurring on faults due to ongoing tectonic deformation. |
Stick-Slip | Stick-slip is caused by the surfaces alternating between sticking to each other and sliding over each other, with a corresponding change in the force of friction. |
Aftershocks | An aftershock is a smaller earthquake that occurs after a previous large earthquake in the same area. |
Earthquake | The vibration of the Earth produced by rapid release of energy. |
Focus | The actual point in the Earth's Crust where earthquake waves begin. |
Displacement | Earth crustal displacement refers to scientific theory which describes the large scale motions of the Earth's crust. |
Horizontal Displacement | The component of the slip of a fault that is parallel to the strike of the fault. |
Vertical Displacement | In tectonics, vertical displacement is the shifting of land in a vertical direction resulting in a permanent change in elevation. |
Normal Fault (divergent plate boundary) | This occurs when the crust is extended. It is also called an extentional fault. |
Thrust Fault (convergent plate boundary) | This is the same sense of motion as a reverse fault, but with the dip of the fault plane at less than 45 degrees. |
Strike-Slip-Fault (transform plate boundary) | The fault surface is usually near vertical and the footwall moves either left or right or laterally with very little vertical motion. |
Seismologist | Earth scientists, specialized in geophysics, who study the genesis and the propagation of seismic waves in geological materials. |
Seismology | The scientific study of earthquakes and the propagation of elastic waves through the Earth. |
Seismograph | instruments that sense and record the motion of the Earth. |
Seismogram | A graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time. |
Seismic Waves | Waves of force that travel through the Earth or other elastic bodies, for example as a result of an earthquake, explosion, or some other process that imparts forces. |
Surface Waves | A mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. |
Body Waves | A seismic wave that moves through the interior of the earth, as opposed to surface waves that travel near the earth's surface. |
P-Waves (primary wave) | Waves, that can travel through gases, solids and liquids, including the Earth. P-waves are produced by earthquakes. |
S-Waves (secondary wave) | one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves. |