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Paper代写:The San Francisco Earthquake & Its Geological Significance

2018-02-11 | 来源:51due教员组 | 类别:Paper代写范文

本篇paper代写- The San Francisco Earthquake & Its Geological Significance讨论了旧金山地震。1906418日上午,旧金山发生了地震。据估计震级为7.8级,这是北美最具破坏性的地震之一。这次地震直接死亡人数超过700人,死亡总人数约为3000人,超过一半的人无家可归。尽管此次地震强度很大,但大部分的破坏都是由震后的火灾造成的。此外,由于旧金山地震是第一次如此高震级的地震,所以也记录了资料,这对地质和地震学的研究非常重要。本篇paper代写51due代写平台整理,供大家参考阅读。

San Francisco Earthquake,旧金山地震,paper代写,代写,essay代写

On the morning of April 18, 1906, the San Francisco earthquake occurred. With the estimated moment magnitude of 7.8, it was one of the most devastating earthquakes in North America. The number of direct death caused was over 700, and the total number of death was about 3000 (Altshuler, 2011). Out of a population of 400,000 in San Francisco, over a half became homeless. Despite the intensity of the earthquake, most of the destructions were done by the fire in the city, which was either caused by the earthquake or people trying to get compensation from their insurance companies. Due to the damage caused in the pipe system, little water was available for putting out the fire. The firemen had to blow up blocks of buildings to prevent the fire from spreading. Consequently, 80% of the city was destroyed by the earthquake and the fires that followed (Altshuler, 2011).In many areas, including firefighting, victim resettlement and recovery and reestablishment of the city, the earthquake served as a precedent. Moreover, as the San Francisco earthquake was the first earthquake of such high magnitude that was documented with photographs, which became significant for the development of geology and seismology studies.

Tectonic activities within the San Andreas Fault were the main cause of the San Francisco Earthquake. The San Andreas Fault, which is a right-lateral strike slip fault, is located between the Pacific Plate and the North American Plate. It is estimated to have a length of 1300 kilometers, covering the western and southern areas of California and part of Mexico (Boschi, Bonafede, &Dragoni, 1983). The fault was first discovered by Professor Andrew Lawson. After the earthquake of San Francisco, Lawson believed that the fault was ruptured and further extended to the more populated area of Southern California for 485kilometers. The Pacific Plate west of the fault is moving northwest, while the North American Plate is moving southwest. The average annual displacement of the plates is from 33 to 37 millimeters. The relative movements of the plates near the San Andreas Fault is building up enormous amounts of energy, which makes the areas one of the most frequent zones of earthquakes on Earth. The studies of Fialko (2006) has shown that the energy accumulation in the San Andreas Fault is ready to cause another large-scale energy release. While the upper and middle sections of the fault have already experience such releases in 1857 and 1906 respectively, there isn’t any notable releases in the lower part in the recent 300 years.

The San Francisco Earthquake provided valuable documentations for the study of earthquakes. In the investigation of the reason for this earthquake, the elastic rebound theory was proposed. In 1910, through the observations of the surface displacements and patterns of destruction in San Francisco, Henry Reid first formulized the elastic rebound theory, which remains an important reference in the study of earthquake cycles today (Hough, &Bilham,2006). The elastic rebound theory is the earlies and most widely applied theory attempting to explain the reasons for an earthquake. The theory believes that slipping movements within the earth’s crust cause earthquakes. Since the rocks are elastic, the deformed rock at the point of break would rebound after the break happened, which would create tremendous speed and force, releasing the long-accumulated energy in the rocks. Seismic waves are generated due to the elastic rebound in rocks on the two sides of a fault. Since the rocks deep into the crust have already become plastic, elastic rebound can only happen near the surface of the earth. Therefore, the elastic rebound theory can only explain the causes of shallow focus earthquakes, but it cannot explain the reasons for earthquakes originated from deeper sources.

The temporal and frequency studies of earthquakes is one of the most relevant subjects in seismology studies. For the area located near the San Andreas Fault, prediction of the next catastrophe becomes even more crucial. Almost all the existing studies show a high chance of energy release in the area, but before the trigger is pulled, no one can say when for sure. Efforts have been made by geologists to better understand the periodic behaviors of the earthquakes in the San Andreas Fault. Near the Monterey County, California, a place named Parkfield is regarded as an important base for seismic studies. Earthquakes happened there with a period of roughly 22 years. The recorded years of earthquakes were 1857, 1881, 1901, 1922, 1934 and 1966 (Earthquake, 2016). Due to unknown reasons, the earthquake predicted to happen in 1993 delayed till 2004. Since the year of 2004, a project named San Andreas Fault Observatory at Depth, a.k.a. SAFOD, was initiated in Parkfield. By digging into the rock for as deep as three kilometers, scientists are hoping to be able to predict earthquakes more accurately. As a devastating natural disaster, the San Francisco Earthquake demonstrated the destructive forces of nature. However, the study of it has also laid the foundation for modern seismic studies, which helps us better understand our planet earth, and be more prepared when the next disaster strikes.

References

Altshuler, A. (2011). San Francisco Earthquake (1906)

Boschi, E., Bonafede, M., &Dragoni, M. (1983).Interpretation of A Stress Profile Across the San Andreas Fault. Annales Geophysicae, 1(3), 195-198.

Earthquake History (2016) Retrieved from: https://earthquake.usgs.gov/research/parkfield/hist.php

Fialko, Y. (2006). InterseismicStrain Accumulation and The Earthquake Potential on The Southern San Andreas Fault System. Nature, 441(7096), 968-971. doi:10.1038/nature04797

Hough, S. E., &Bilham, R. G. (2006). After the Earth Quakes: Elastic Rebound on An Urban Planet. Oxford; New York: Oxford University Press.

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