# compression earthquake definition

See more. Once determined from a seismograph record, the S-P interval and amplitude are used to mathematically solve for the magnitude, or they may be plotted on a graph called a nomogram to yield a visual solution for the magnitude. This is because both solids and fluids (the atmosphere and bodies of water) can be compressed. Compressional waves are also known as a longitudinal waves because of the way in which they travel through a medium.

triangulation: To determine the location of an earthquake the distance of the earthquake must be determined from at least three seismic recording stations. When the dip angle is shallow, a reverse fault is often described as a thrust fault. Those stresses (compression, tension, shear) build up in the crust until the stress exceeds the strength of the rock or the friction along a preexisting fault. http://physics.taskermilward.org.uk/KS5/html/waves.htm, http://hyperphysics.phy-astr.gsu.edu/hbase/waves/seismic.html, https://wiki.seg.org/index.php?title=Compressional_wave&oldid=38387, Problems in Exploration Seismology & their Solutions, the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Mercalli intensity scale: In order to better understand the long term behavior of a given fault it is necessary to go back to written records of earthquakes that occurred before seismic recording began.

Seismologists can determine the point on a fault where the slippage began, the area (length and depth) of the fault that slipped, the amount of slippage or fault throw (how far the crust moved), and the time it took for the slippage to occur. The magnitude of an Earthquake is measured on the well-known Richter Scale. Learn more.

An intensity of I (not felt) to XII (total damage) is designated according to the amount of damage cited in historic records.

Then, sudden slippage of rock along a fault occurs. an earthquake that occurs after a larger earthquke in the same area.

On the other hand, certain building materials, such as brick and mortar, stone, or concrete, tend to be strong under compression but very weak under tension.…, …turns together to form a compression and then releasing them, allowing the compression to travel the length of the spring. The whole fault doesn't move at one time; only the part of the fault around which the stress exceeded the strength. The Mercalli intensity of historic earthquakes can then be compared to the Mercalli intensity of modern earthquakes that have Richter and/or moment magnitudes. The distance of the seismic recording station from the earthquake epicenter is determined from the time difference between the first arrival of the P-wave and the S-wave.

Damage Factors:  - Loose, unconsolidated sediments, and especially saturated sediments experience stronger ground motions in an earthquake as compared to solid bedrock.

Earthquake Probability:  Seismologists are, however, able to estimate the probability of an earthquake of a given size occurring in a given period of years on a particular segment of a fault.

Let us know if you have suggestions to improve this article (requires login). strike-slip fault - a fault on which the two blocks slide past one another.

Body Waves - travel through the interior of the Earth. Earthquake definition, a series of vibrations induced in the earth's crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating. Blind Thrust Fault Animation.

Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another. Earthquakes . caldera. Because the amplitude recorded on seismograms will decrease with increasing distance from the earthquake the distance must first be determined so that it can be corrected for.