All of the above are hazards associated with earthquakes Seismic risk maps of the U. S. are based on where earthquakes have occurred in the past tectonic plate boundaries mountain belts visible faults on the earth's surface Seismic sea waves are caused by earthquakes submarine landslides volcanic eruptions all of these Geologists use earthquakes to define plate boundaries deduce plate motion analyze the orientation and types of forces involved in plate tectonics all of these Changes in well water levels, microseisms, electrical resistivity of rocks, speed of seismic waves, and porosity can be used to predict earthquakes. The release of stress at one point may cause ruptures at other places along a large fault system, so that earthquake activity may continue for days or weeks. A preexisting fault is not always a requirement for an earthquake. Deep earthquakes may result from sporadic slippage in rocks that are simultaneously undergoing plastic deformation. The greatest number of earthquakes occur within the central regions of lithospheric plates.
Stress is a force applied over a specific area of a rock so as to compress it.
Stress is never considered a factor during the initial stages of faulting When the stress that accompanies strain accumulates beyond the competence of the rock, there is a rupture. The effect of stress is to cause strain which is a measure of the amount of body is deformed by stress. With the assistance of this instrument it is possible to isolate the major kinds of elastic wave motion involved in an earthquake. Mercalli scale Magnitude Intensity Richter scale This type of wave is represented by pulses of energy that are transmitted in such a way that the movement of rock particles is parallel to the direction of propagation of the wave itself. By using the information from the arrival time of the P and S waves at a seismic station the following can be determined.