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Due to its placement on the San Andreas fault line

April 3, 2019 0 Comment

Due to its placement on the San Andreas fault line, California is prone to earthquakes at any given moment. California is a seismically active region that could be hit by a mega-earthquake reaching a magnitude of up to 8.2. Records of California earthquakes demonstrate the great physical damage caused in the areas they take place in. In order to have a better understanding on how earthquakes impact California, this research will focus on how earthquakes occur, the danger they pose to people that inhabit the areas they occur in, the prolonged economic costs, mitigation, and the public concerns earthquake uncertainty brings.
There are three kinds of plate tectonic boundaries that cause Earthquakes. One plate tectonic boundary is a divergent boundary that occurs when two tectonic plates move away from each other. As a result, tectonic boundaries allow magma from the mantle to rise which forms a new crust that solidifies and creates new rocks underwater. Another plate tectonic boundary is a convergent boundary, that is the collision of two plates. If the two plates push up against each other with the same amount of force then mountains are formed. If one plate has more density than the other one, then that plate will subduct beneath the other plate. The third plate tectonic boundary is a transform plate boundary, it occurs when two plates slide past each other in opposite directions. Unlike divergent and convergent boundaries, transform plate boundaries do not form magma, instead, the crust is broken.
California, in particular, has had severe earthquake damages caused by the San Andreas continental transform fault. Early in the morning of April 18, 1906, one of the greatest fires in the history of the world broke out in San Francisco. Hardly had the fire ended when news came of a great crack in the earth southwest of the city. Thus came dramatically to notice the surface trace of the San Andreas Fault, broken anew in 1906 (Wood, 1934). On the North American Plate, San Francisco is located just East of the San Andreas Fault. The earthquake was estimated to be a magnitude of 7.9, causing major cities and buildings to collapse. The earthquake only lasted several minutes but the high magnitude of the earthquake caused several fires around the city, burning and destroying many cities. Even neighborhoods that had not been severely damaged by the quake burned to the ground. After 4 days, 80 percent of San Francisco had been destroyed, and half of its population of 400,000 was homeless (Prothero, 2018). The earthquake destroyed the pipeline that carried water from the San Andreas Lake to San Francisco, causing a stop to the water supply in the city. As a result, many of the fires destroyed a large part of San Francisco since the lack of water supply made it impossible to control the fires started by the earthquake.
Another major earthquake that damaged and caused change in California policies, was the 1994 Northridge earthquake. The Northridge earthquake of 17 January 1994, killed 57 people and injured an estimated 10,000 persons (Tierney, 1997). The Northridge earthquake was estimated to be a 6.7 magnitude which destroyed many buildings and caused the deaths of many individuals. Following the Northridge Earthquake, a number of legislative changes were made. One of the changes implemented by the California Legislature was the California Earthquake Authority, which is an organization that promotes California earthquake insurance policies to protect homes from the damage of earthquakes. As California introduced new laws to help the mitigation of earthquakes, the 1933 Long Beach earthquake provided more than ground motion data to drive earthquake engineering. The Long Beach quake impelled both the government and businesses to take further actions on making California safe against seismic hazards. The reason the state government responded quickly to 1933 earthquake in Long Beach, was because 15 of 35 schools were completely ruined, and 41 schools in Los Angeles were deemed unsafe for occupancy. Public indignation at the collapse of school buildings led to an outcry for making structures truly earthquake proof. Therefore, the governor signed the Field Act, giving responsibility for overseeing building and rebuilding of all school building in California to the State Division of Architecture and incorporating a Structural Engineers Association recommendation that school buildings be designed for horizontal accelerations amounting 10% of gravity (William, 2000). The new changes in California policies help mitigate the hazardous effects earthquakes impose to California.
Earthquakes in California have caused prolonged economic effects, due to the unsafe outcomes they produce. For instance, the Northridge earthquake is the most costly disaster in U.S. history, in terms of dollar loss; costs continued to rise as more damage was uncovered, repairs were made, and disaster-related claims were paid out (Tierney, 1997). Due to recurring fires and burned homes, the 1994 Northridge quake impacted California’s economy. Recently-issued government estimates placed the losses due to direct earthquake damage at approximately $25 billion (Governor’s Office of Emergency Services and Federal Emergency Management Agency, 1996), and researchers who were tracking Northridge-related losses believe `it was quite possible that total losses, excluding indirect effects, could have reached as much as $40 billion’ (Eguchi, et al, 1996). The unpredicted shaking of earthquakes destroy numerous amounts of structures, such as gas or water pipelines creating a high risk of fires. As demonstrated, the cost to rebuild and fix the destruction earthquakes generate are costly. As a result, California has invested in devices that help the detection of earthquakes.
Throughout the years, California has worked to mitigate the catastrophic effects of earthquakes. In fact, due to the San Andreas fault, there is a reasonable probability, if not a virtual certainty, that at some time in the future an earthquake of destructive intensity will cause great loss of life and damage to property unless adequate protective measures are carried out (Davis). As a result, in the United States, hundreds of millions of dollars have been spent installing equipment to monitor possible earthquake precursory phenomena along the San Andreas fault system in California. The mass of data collected from each new major earthquake in the region serves to increase the chances of predicting the next (Degg, 1993). With the use of equipment that detects the seismic waves of an earthquake, such as a seismograph, the probability of predicting this natural disaster increases. Seismographs are placed at the surface of the Earth so when the ground trembles and the equipment starts to move, the intensity of the seismic waves are recorded. The device helps detect quakes that are too small for humans to feel, allowing the movement of the tectonic plates to be recorded. The data collected is then used to help aid in the prevention of earthquakes.
Overall, earthquakes in California are hazardous to the community as they are causes of deaths and ruins in infrastructure. They ultimately originate hazards and impose economic costs, causing public concerns. In the case of San Francisco’s 1906 earthquake, it is visible how earthquakes can be extremely catastrophic as it caused water supply to be stopped. This in effect causes individuals to be affected by earthquakes in certain ways. In addition, the Northridge earthquake is also an example to acknowledge that earthquakes are also costly as many buildings had to be reconstructed and new policies had to be made. In summation, earthquakes in California impact societies significantly as lives may be changed due to the destruction of its nature.