Earthquakes

Junha Lee 9F

Introduction

Hollywood movies are thought to be the best movies in the whole world. One of the most popular genres of Hollywood movies are disaster movies. The actors of the movie and their acting is also important, but disaster movies are usually graded by how good the director described the disaster with computer graphics. This article will describe how the movie ‘Earthquake’ which is a movie that showed an earthquake in Los Angeles, and real earthquakes differ.

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Location of Earthquakes

Earthquakes and volcanoes are usually found in a ring called the ‘Ring of Fire’. The Ring of Fire is an area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur. In a 40,000 km (25,000 mi) horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements. Also, about 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire. The Ring of Fire is a direct result of plate tectonics and the movement and collisions of lithospheric plates. The motion of the fault generates numerous small earthquakes, at multiple times a day, most of which are too small to be felt. The picture below shows the earthquakes that occurred recently in California. In the film Earthquake, the earthquake occurred in Los Angeles, California. One of the most famous and active faults in the Ring of Fire is the San Andreas fault. Because the fault is very active, the motion of the fault generates small earthquakes at multiple times a day. Also because the San Andreas fault is directly in touch with California, most of earthquakes occur in California. The pictures show that earthquakes occur very frequently in California. Which is also the reason why the films about earthquakes are usually located in California.
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How does the hazard work in reality?

Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little.The rocks do not just slide smoothly, but the rocks catch on each other. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs.

Effects of earthquakes

Most earthquake-related deaths are caused by the collapse of structures and the construction practices. They are caused by the broken parts of buildings from the earthquakes and people usually get hurt by getting hit by the broken parts. They play a tremendous role in the death toll of an earthquake. Building practices can make all the difference in earthquakes, even a moderate rupture beneath a city with structures unprepared for shaking can produce tens of thousands of casualties.


Fires, often associated with broken electrical and gas lines, is one of the common side effects of earthquakes. Gas is set free as gas lines are broken and a spark will start bringing "inferno". To complicate things water lines are broken and so there is no water to extinguish the fire. The San Francisco earthquake of 1906 caused 90% of damage by fire.


For sure, one of the most dangerous effects of an earthquake is a Tsunami. Tsunamis are giant waves that can cause floods and in some cases may reach up to 100 feet in height. These deadly waves strike a great distance from the epicentre. Tsunamis often result from sub-sea faulting of ocean floor sending seismic shocks through the water and creating large waves of low amplitude but of long period, moving at 500-700 mph.

Case Study

The one actual example of an earthquake occurred in Fort Tejon on the January 9th of 1857. This earthquake occurred in Fort Tejon, California. It is located in the Grapevine Canyon between the San Emigdio Mountains and Tehachapi Mountains. The magnitude of the earthquake was approximately 7.9, which was the strongest earthquake in California in history. A woman at Reed Ranch near Fort Tejon was killed by the collapse of an adobe house, and an elderly man fell dead in a plaza in the Los Angeles area. The Fort Tejon earthquake was different from the film 'Earthquake' because the Fort Tejon earthquake only gave death to 2 people, but the film 'Earthquake' showed a massive amount of people dying.

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How does the clip 'San Andreas' differ from reality?

What the Movie Got Correct

Compared to many disaster movies, San Andreas got a lot right in terms of earthquake safety messages and earthquake science. During the whole movie, we can hear "Drop, Cover, and Hold On" as an message for self-protection. Also, people running or trying to escape buildings are shown getting injured, which is quite common during an real earthquake. Lastly, the sequence of earthquakes triggering earthquakes in other areas is very realistic and has happened in California many times. Scientists classify "triggered" earthquakes differently from "aftershocks," which are smaller earthquakes within the area of the "mainshock."


What the Movie Got Wrong

The San Andreas fault is not long and deep enough to have a magnitude 9 or larger earthquake as depicted in the movie. The largest historical earthquake on the northern San Andreas was the 1906 magnitude 7.9 earthquake. In 1857 the Fort Tejon earthquake occurred on the southern San Andreas fault; it is believed to have had a magnitude of about 7.9 as well. Computer models show that the San Andreas fault is capable of producing earthquakes up to about magnitude 8.3. Critically, the San Andreas fault cannot create a big tsunami, as depicted in the movie. While a part of the fault near and north of San Francisco is offshore, the blocks on either side of the fault slide past each other horizontally; this will not cause significant vertical motion of the ocean floor that pushes up water, as need to cause a damaging tsunami.

Conclusion

In the article, I compared a real earthquake and the films 'San Andreas' and 'Earthquake' and found out how they differ. This hazard is realistic and unrealistic at the same time. The hazard is realistic in the film 'San Andreas' because there are lots of safety messages during the movie such as Drop, Cover, and Hold on." The hazard is unrealistic in the film because there is a massive tsunami even though tsunamis can not form at the fault near and north of San Francisco is offshore. The location of the film is very realistic because there are a huge amount of earthquakes every day in California. If I had to give the film stars to grade the film, I would give it 3.5 stars out of 5 stars.