Earthquakes

Axia CollegeSeptember 20, 2009Looking at the pieces of a jigsaw puzzle, one can see how the 3D puzzle floatingaround are then locked in place. But, the earth crusts do not fall into the form of thejigsaw puzzle category, as the earth crust is not locked in place. Nevertheless, the platesconstantly stay in motion. Trying to see the plates as they converse and moves againsteach other may not be visual to individuals. Individuals’ can only feel the result throughan earthquake. This paper will discuss the three types of plate boundaries, their motion,and, earthquakes.

The lithosphere or the outermost shell of the earth is 100 kilometers. All this area isthe uppermost area of the mantle and is also composed of the crust. Numerous plates thatare smaller in size makes up the lithosphere , in total there are seven plates. The earthsseismic and volcano activity make an occurrence where the plates falls together whetherat the plate margins or boundaries itself.

English: A seismic wave is an elastic wave generat...

Internationalization of the diagram Proeminent_hot...

USGS diagram of San Andreas Fault

There are three ways the earth falls together inone. Divergent plate boundary is one of the three ways. Divergent occurs when the twoplates Separates and then starts to spread as new material coming from a generatedmantle. In cross section, the Earth releases its internal heat by convecting, or boilingmuch like a pot of pudding on the stove. Hot asthenospheric mantle rises to the surfaceand spreads laterally, transporting oceans and continents as on a slow conveyor belt. Thespeed of this motion is a few centimeters per year, about as fast as individuals fingernailsgrow. The new lithosphere, created at the ocean spreading centers, cools as it ages andeventually becomes dense enough to sink back into the mantle. The subducted crustreleases water to form volcanic island chains above, and after a few hundred millionyears will be heated and recycled back to the spreading centers (USGS). According to theUSGS, one individual can see how evident that when the new material rises the rigidplates is now tied in together. The oceanic ridges are the asthenospheric spreadingcenters, creating new oceanic crust. Subduction zones appear as deep oceanic trenches.

Most of the continental mountain belts occur where plates are pressing against oneanother. The white squares locate examples given here of the different tectonic andearthquakes environments (Louie and Anderson, May 2001).

Plates however is destroyed elsewhere, and the process now is called the convergentplace boundaries. Convergent boundaries are two plates that meet and collided together,as a result earthquakes, volcano and crustal deformation occurs. The plates aredifinitley force under each other. Convergent plate boundaries can be found oceanicareas. According to the Geology website; here is one of the ways convergentboundaries operates. “When continental and oceanic plates collides the thinner and moredense oceanic plate is overridden by the thicker and less dense continental plate. Theoceanic plate is forced down into the mantle in a process known as "Subduction". As theoceanic plate descends it is forced into higher temperature environments. At a depth ofabout 100 miles (160 km) materials in the subducting plate begin to approach theirmelting temperatures and a process of partial melting begins (Geology.com).” Others areliable to occur on land. Chambers are then become a production called magma which isabove the oceanic plates. Two prominent examples of where convergent plate boundariesoccurs is the Himalaya Mountains and the Japanese Island.

The conservative or transform plate boundaries, now more commonly known asconservative because the plates do not make any addition or destroy the margins. Theplates slide past each other in a horizontal form passing each other, meaning differentdirections. Regardless of the movements in different directions, the process stillcause friction. The result of the friction is then an earthquake which shakes the earth dueto the movement or the big rocks and the approach of the enormous energy that is thenreleased. One known example of the c conservative plate boundary can be located in theWest Coast area United States. In the West Coast area, and individual can find theplates movements going North within the Westerly direction, and just going by the NorthAmerican Plate. This was the main cause of the San Andreas Fault. The Alpine Fault inNew Zealand is another prominent example and even the North Anatolian Fault locatedin Turkey.

An earthquake is what happens when two blocks of the earth suddenly slip past oneanother. The surface where they slip is called the fault or fault plane. The locationbelow the earth’s surface where the earthquake starts is called the hypocenter, and thelocation directly above it on the surface of the earth is called the epicenter (Lisa Wald,2009). When the earth quake and shakes many things are happening. The Seismic wavesat the time begin to propagate from the focal point of the earthquake. Most of the wavestravels through the body of the earth while some may travel near the earth surface oralongside the area. Though some of the faults may stick together and individual will findthe rest of the blocks still in moving process. The reason; the energy that would normallypush the blocks past each other is stored at this time, but as the force of the blocks thatare moving gets a release of the jag edges of the fault and no longer sticks, the energy instorage now releases on the outward in many direction from the fault in Seismic waves.

The Seismic waves cause the earth to shake as movements projects through. Once themovements of the waves reaches the earth’s surface, the ground will then shake includingany objects or material even humans, animals and other living things.

Scientist measures the earthquakes not with a tape but using Seismogram recordingsthe see or find on the Seismograph located at the surface of the earth to make adetermination how large was the actual size of the earthquake. If the long wiggle linewiggles more, the earthquake was very big. On the other hand short line with very littlewiggles indicates the earthquake was small.The length of the wiggle depends on the sizeof the fault, and the size of the wiggle depends on the amount of slip (Lisa Wald, TheGreen frog news). Two main types of body waves an earthquake creates are called the“P” waves and “S” waves. The “P” wave is known as the primary wave. Similar to themotion movements of a slinky the “P” waves follow in the same movements. Theprimary wave is the fastest seismic wave and is the first wave to make it to a seismicstation. The P wave can move through solid rock and fluids, like water or the liquidlayers of the earth. The primary waves pushes and pulls the rock it moves through justlike sound waves push and pull the air (UPseis, 2004).

The “S” wave known as the secondary, because of the second feeling an individualwould normally feel in an earthquake. The “S” wave is slower than the primarywave. The secondary waves only moves through solid rock and not through any factor ofliquid medium in no form whatsoever. The “S” waves moves perpendicular directly towhere the wave is travelling. The secondary wave was the factor that led Seismologist toconclude the outer core of the earth is liquid. S waves move rock particles up and down,or side-to-side--perpendicular to the direction that the wave is traveling in “the directionof wave propagation”( UPseis, 2004).

ReferencesBolt, B.A. (2003). Earthquakes, Fifth Edition. W.H. Freeman.

Fowler, C.M.R. (1990). The Solid Earth, An Introduction to Global Geophysics.

Cambridge University Press.

Louie, J. (October 9, 1996). Earthquake Effects in Nevada Seismology Laboratory.

Retrieved September 20, 2009, Fromhttp://www.seismo.unr.edu/ftp/pub/louie/class/100/effects-kobe.htmlWikipedia. (July 14, 2008). Great Hanshin Earthquake in Wikipedia. RetrievedSeptember 20, 2009, fromhttp://en.wikipedia.org/wiki/Great_Hanshin_earthquakeUrban Environment ,(May , 2007).United News of Bangladesh. Could quake shake thnation’s capital?”USGS, (2009). Science for changing world. The Science of Earthquake. RetrievedSeptember 20, 2009.

Wald , Lisa (2009). The Science of Earthquake. The Green Frog News. RetrievedSeptember 20, 2009. From; www.thegreenfrongnews.comUPSeis ,(2009).What is Seismology. Retrieved September 20, 2009. Fromhttp://www.geo.mtu.edu/UPSeis/waves.htmlWald , Lisa (June, 2009). Earthquakes. Geological Survey-earthquake Hazard Programs.

Retrieved September 20, 2009. From www.thegreenfrognews.comhttp://www.ahsfoundation.comhttp://rashidfaridi.wordpress.comhttp://geology.com

English: Convergent plate margins around the world

P-waves and S-waves from a seismograph

English: Accretion subduction of oceanic lithosphe...