Good Essay About Geology
The Loma Prieta Earthquake 1989
The context critically discusses the factors that are connected to the Loma Prieta earthquake that took place in 1989. An earthquake is a physical occurrence where vibrations are caused by underlying rocks that are breaking under a lot of stress. The rocks are situated under the earth’s crust and are mostly caused when two tectonic plates come together, and pressure is created along the fault lines. It is then released towards the earth’s surface resulting in an earthquake (California, 1990).The Prieta earthquake had a series of damaging effects ranging from the human, social, and economical effects where some of the aftermaths are still being felt by the victims.
In 1989, the Loma Earthquake occurred in the region of the Santa Cruz Mountains that caused a total number of 63 fatalities, 3,557 injured related cases. It also destroyed a lot of property, which is estimated to be about $6 billion (Holzer, National Science Foundation (U.S.), & Geological Survey (U.S.), 1998). This is the biggest earthquake ever to occur and recorded along the fault lines of the San Andreas from the previous massive earthquake back in April 1906.
Diagrammatic representation of the map
Most of the property devastation that was caused by the earthquake happened in the Oakland and San Francisco areas that were about 100 kilometers northwards from the fault line where the section moved in the San Andreas region. A lot of houses collapsed while several reinforced –concrete viaducts were destroyed in four areas of Oakland and also San Francisco. The areas namely: Embarcadero Freeway, Nimitz Freeway, which is in Highway 10, Oakland and the Interstate. Several communities that were also affected and experienced heavy damage include Los Gatos, Watsonville, and Santa Cruz.
The process of liquefaction that was evidently identified by the occurrence of slumping, lateral settling and sand boils that were located in areas more than 110 kilometers from the origin of the earthquake. The liquefaction resulted in massive destruction of buildings and other facilities in the San Francisco. It spread to the coastal region of Oakland and also Alameda located in the shore area of the eastern bay of San Francisco. The liquefaction greatly contributed to the destruction of property that were located in the Monterey Bay and Santa Cruz areas, which are both located in proximity to the epicentral region. Some of the destroyed properties due to liquefaction include bridges, buildings, highways, port facilities, pipelines, levees and airport runways. Surface soil conditions of the environment that augmented speeding up around the San Francisco region ("Historic Earthquakes," n.d.). It greatly influenced the buildings and other structures structural damage that may also have caused the liquefaction problems experienced in the areas that had loose and sandy fills.
Carefully engineered buildings, as well as those located near the earthquake’s epicenter, performed better than expected all through the earthquake. Several hospitals and buildings that were in that area sustained very little cosmetic and system damage while other major damage did not occur. An estimated $81 million worth of damage was sustained by the schools in the area (Holzer, National Science Foundation (U.S.), & Geological Survey (U.S.), 1998).
The majority part of the impressive destruction of buildings and other structures were sustained by the un-reinforced buildings that were made of wood-frame roofing and floors that were supported by the weak brick walls. A lot of these buildings were destroyed because they were located in the regions near the earthquake’s epicenter, near Monterey and San Francisco. Severe tremors around Santa Cruz resulted in a lot of damage to the weak buildings in the area where of these buildings were located in the Pacific Garden Mall area of Santa Cruz.
Up to 1,000 rock falls and landslides occurred in the region close to the epicenter. For example, one of the slides that occurred on the State-Highway 17 caused the highway to be closed for nearly a month before normal traffic resumed. The earthquake formed a pattern of northwestward fractures that were extending towards the north end direction of the aftershock from the epicenter. Due to that, the surface fracturing that might have contributed to the appearance of the main tectonic faulting. This is along the San Andreas, which is near the Mount Madonna Road where some cracks displayed two centimeters of right-lateral displacement ("Live Science: Scientific News, Articles and Current Events," n.d.).
Exterior fractures were located about 12 kilometers northwest from the epicenter. Areas of compressed and deformed surfaces were observed at the foot of Santa Cruz Mountains. In the towns of Los Gatos and Los Altos, deformed surfaces were observed to be related to the areas that experienced a lot of destroyed underground service lines and structural damage. Other towns include Corralitos, Boulder Creek, and other smaller towns. The aftershock effects started to decrease quickly with time, but the aftershocks experienced were less compared to other earthquakes of such scale (Holzer, National Science Foundation (U.S.), & Geological Survey (U.S.), 1998).
The Prieta Earthquake of 1989 wrecked the harmony of the San Francisco Bay area. The earthquake was a wake-up call to the people of California to prepare for an even potentially worse earthquake in the future. Preparation for another earthquake will greatly reduce the further damage to property and loss of lives as witnessed from this force of nature in the San Francisco Bay area.
1989 San Francisco Earthquake - Facts & Summary - HISTORY.com. (n.d.). Retrieved from http://www.history.com/topics/1989-san-francisco-earthquake
25 Years After Loma Prieta, Earthquake Science Is Transformed. (n.d.). Retrieved from http://www.livescience.com/48332-loma-prieta-earthquake-25th-anniversary.html
California. (1990). 1989 Loma Prieta earthquake: Summary report. Sacramento?: The Department.
Historic Earthquakes. (n.d.). Retrieved from http://earthquake.usgs.gov/earthquakes/states/events/1989_10_18.php
Holzer, T. L., National Science Foundation (U.S.), & Geological Survey (U.S.). (1998).The Loma Prieta, California, earthquake of October 17, 1989. Washington: U.S. G.P.O.