The Frequency and Effects of Earthquakes around the World

By Nicky Lee

Introduction

Recently, one big shock damaged Haiti. It caused numerous effects to wound many people and damage many buildings. Earthquakes are one of many catastrophes. Sometimes an earthquake is related to a Tsunami which is a hazardous natural disaster from the deep sea or ocean. According to the experts, “Tectonic earthquakes will occur anywhere within the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. In the case of transform or convergent type plate boundaries, which form the largest fault surfaces on earth, they will move past each other smoothly and seismically only if there are no irregularities or asperities along the boundary that increase the frictional resistance” (“Earthquakes”). As you read, the natural disasters such as earthquakes, tsunamis or avalanches damaged nature and people who are especially poor and completely destitute. Of course, some of the geologists who are specialists of plate tectonics are still studying up on earthquakes and researching the makeup of the soil. A great amount of pressure will occur underneath the mantle of the Earth while the Earth’s plates are moving in the opposite direction of each other. The lithosphere, which is the rigid outer layer of earth, would break when the pressures from the Earth break out. For instance, think about a little stick. When you give a force to each side of a stick, it is easier to break than when you just set it in a normal position. Actually, this is similar to earthquakes. It means that two forces between different sides of the lithosphere are powered to each side. When these pressures and stresses are great enough, the crust will break. After the crust breaks, the pressure will decrease as energy is moving among the Earth's layers in form of waves, and earthquakes happen. People need to recognize some information about earthquakes, especially, the size and frequency of occurrence, records of earthquakes’ effects, and how to measure the earthquakes’ degrees.

Size and Frequency of Occurrence

Usually minor earthquakes are taking place nearly constantly around the world like in Alaska or Oklahoma in the U.S. as well as on the Asian continent. Also, these usually occur in Chile, Peru, Indonesia, Iran, Pakistan, the Azores in Portugal, Turkey, New Zealand, Greece, Italy, and Japan, but earthquakes can occur almost anywhere, including New York City, London, and Australia. Larger earthquakes, however, come about less frequently. Therefore a few countries or cities are damaged badly seismically by magnitudes 4~6 in a particular time period.

Most of the world's earthquakes (90%, and 81% of the largest) take place in the 40,000-km-long, horseshoe-shaped zone called the circum-Pacific seismic belt, also known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate. Massive earthquakes tend to occur along other plate boundaries, too, such as along the Himalayan Mountains. With the rapid growth of mega-cities such as Mexico City, Tokyo and Tehran, in areas of high seismic risk, some seismologists are warning that a single quake may claim the lives of up to 3 million people(“Earthquake”).

Measuring the Size of An Earthquake

Magnitude (“Earthquakes and Volcanoes”)

Modern seismographic systems precisely amplify and record ground motion (typically at periods of between 0.1 and 100 seconds) as a function of time. This amplification and recording as a function of time is the source of instrumental amplitude and arrival-time data on near and distant earthquakes. Although similar seismographs have existed since the 1890's, it was only in the 1930's that Charles F. Richter, a California seismologist, introduced the concept of earthquake magnitude. His original definition held only for California earthquakes occurring within 600 km of a particular type of seismograph. His basic idea was quite simple: by knowing the distance from a seismograph to an earthquake and observing the maximum signal amplitude recorded on the seismograph, an empirical quantitative ranking of the earthquake's inherent size or strength could be made. Most California earthquakes occur within the top 16 km of the crust; to a first approximation, corrections for variations in earthquake focal depth were, therefore, unnecessary.

Largest and Deadliest Earthquakes by Year (1990 – recent)

The largest earthquakes since 1990 occurred off the West Coast of Northern Sumatra in Southeast Asia. Many people who enjoyed the leisure on the beach were killed or wounded by the biggest earthquake. Actually it was the Tsunami made by earthquakes. It was initially reported as moment magnitude 9.0 (“2009 Sumatra Earthquakes”). The hypocenters of main earthquakes were approximately 160 kilometers (100 miles). According to the U.S. Geological Survey, a total of 227,898 died and this is one of the ten worst earthquakes on record (“2009 Sumatra Earthquakes.”).

The deadliest earthquake occurred in Haiti in January 2010. Until now, it is impossible to count and estimate how many people have died because there has been a lot of destitution and rescue and search team have had problems.

Conclusion (Prevention)

As you know, earthquakes, which are kinds of natural disasters in the world, are shaking of ground caused by movement of the earth’s crust. Although the Earth’s plates are moving in the opposite directions of each other, they make great impacts on the lithosphere. When the plates move, they stress on each other and themselves. When these pressures and stresses are great enough, the crust breaks. After the crust breaks, the pressure will decrease as energy moves among the Earth's layers in the form of waves, and earthquakes happen. Many scientists are continuously thinking of ways to try and reduce earthquake power. Some are trying to lessen the friction between colliding plates. According to the special instruments that are now in existence to give warnings in California, Japan, and New Zealand, little vibrations show if land has begun to shift dangerously on a certain side of a fault. Other instruments are used to detect certain gases collecting in groundwater.

Architects are also designing earthquake-proof buildings, constructing on rock instead of gravel, or on soft sand or clay. Large structures are made with strong frameworks of steel or reinforced concrete, so that the frame stands firm even if the ground is shaking. The pyramid-shaped Transamerica building in San Francisco was designed in this fashion. Researchers are always trying to reduce the impact of earthquakes. They continue to study and experiment with ways to tame the Earth. However, we all still have much more to learn before we can control the power of one of nature’s most amazing phenomena.

Works Cited

“2009 Sumatra Earthquakes.” http://en.wikipedia.org/wiki/2009_Sumatra_earthquakes
Archer, Jules. Earthquake! New York: Crestwood House, 1991. 10 Feb 2010.

“Earthquakes.” Wikipedia. Web. 28 Jan. 2010.

“Earthquakes.” http://mediatheek.thinkquest.nl/~ll125/en/earthqke.htm

Lampton, Christopher. Earthquake. Brookfield, Connecticut: The Millbrook Press, 1990. 10 Feb 2010.

Spence, William, and Stuart A. Sipkin, and George L. Choy. Earthquakes and Volcanoes. Volume 21(1). Web.1989. 4 Feb 2010.

Van Rose, Susanna. Eyewitness Books: Volcano & Earthquake. New York: Alfred A. Knopf, 1992. 10 Feb 2010.

The Effects of Natural Disasters

By Gayane Ambaryan

Natural disasters, such as an earthquake, hurricane and others can have many unpredictable effects on a society, including economic, structural and even mental. Many people can be killed and lose their property. Many houses, schools and hospitals can collapse and many factories, roads and railways destroy. So there are various possible effects due to natural disasters. This essay is going to describe some of them.

The first effect of a natural disaster is economical. Earthquakes, hurricanes and other disasters strike suddenly and lead to loss of property and businesses and that can have severe long-term economic consequences. Thousands of people lose their financial resources and jobs which significantly slows down economic growth. Usually, rebuilding an economy that has been destroyed by a natural disaster takes a lot of time, resources and international financial assistance. It takes more money and time than originally expected. In some cases, especially in countries with an already poor economy, it can take more than ten years to get the economy back on track.

The next effect of a natural disaster is mental. Because disasters always happen unexpectedly, people lose not only their homes and jobs, but first of all they lose their relatives and that leaves them with psychological trauma. Emotional pain is usually hidden at the outset, but it often lingers, to emerge long after. People usually make adjustments, but for some of them it will never be the same. They will never again have what they had. Even those who try hard to put the disaster in the past and forget about it don’t usually live in quite the same way. They usually live with emotional scars the rest of their lives.

In conclusion, any kind of natural disasters can be really tremendous. They mostly occur suddenly, and people usually aren’t expecting them. Large numbers of people can become homeless and unemployed, and they can lose everything that they had. The natural disasters can have many other effects but we highlight only the two most significant ones: economical and mental. Earthquakes, hurricanes, tsunamis, forest fires, and tornados are happening more often than ever before, and have great effects on our life.

The Impact of Earthquakes

By Satomi Yanagi

In recent years, earthquakes have happened in Japan more than any other country, including China, Australia and so on. If earthquakes happen, people can’t avoid them. Because the destructive power is terrible, unfortunately, nature, structures and people suffer from earthquakes.

About two years ago, in China, a big earthquake happened. The most impressive scene was the mountain range that totally disappeared. The cliffs slid down and the trees were broken after that. It was terrible. We couldn’t see the beautiful mountain like before. We could only see rocks and earth. Many people got buried under the earth and died. In the case of Sumatra, a big wave called “Tsunami” came after the earthquake. People ran trying to escape that. However the speed of a tsunami was faster than they had imagined. Unfortunately the tsunami took away houses, cars, and human lives.

Second of all, structures are damaged from earthquakes. On January 17th, 1995, the Hanshin Awaji earthquake happened in Kansai region. During the earthquake, the air was very dry; as a result, fires happened in many places. Fire trucks tried to go there; however, roads were covered with debris. Moreover, many media vehicles disturbed fire trucks and people who ran away. Even if houses weren’t burned, they were seriously damaged. The roofs fell down, and furniture was destroyed.
The influence of earthquakes on people’s minds is the most important problem. People who lost their houses have to live at evacuation sites. At evacuation sites, they can’t sleep well because a lot of people live there so it is noisy and unsanitary; moreover, they don’t have enough space to take in a lot of casualties. After they live at there, someone goes to makeshift housing. Unfortunately, the majority of them to go there are elders. They have to live by themselves without enough money. In addition, dying alone becomes a social problem. Sometimes, they aren’t found until few weeks after they die.

Earthquakes take away everything. Even if people are saved, they might lose their family, house, or precious items. In Japan, houses which can change the power of earthquakes into heat energy have been invented. However the power of earthquakes is incalculable. If a big earthquake happens, we have no way to avoid it.

The Effects of an Earthquake

By Keisuke Nakagawa

The impact of an earthquake is very serious for our life. Whenever earthquakes occur, we suffer from the damage. The damage affects economy, social organization, and nature. In this essay, I’m going to talk about the effects.

First, an earthquake gives us economic effects. Of course, the earthquake can break buildings. Therefore, offices and factories would be destroyed. If so, economic activities of the firm must be stopped. Such problems will be one more. The problems will come at the time of coming of an earthquake. It will affect not only each company but also the national economy. The efficiency of the national economy will get worse. An earthquake can destroy the economic activities.

The second effect is for social organization. The cruelest trouble is death of people. Every time a strong earthquake comes, many people are killed. Not to mention, that brings intense sorrow for survivors. Reduction of victims is a challenge for the nations. The worst situation is the outbreak in the biggest city. The victims will be more. And the headquarters of the nation will get damaged too. The collapse of the core will bring stronger chaos for the disaster area, because rescue and aid won’t work properly.

The third is effects for nature. An earthquake makes bad problems for the environment. The soil will be cracked. It causes landslides and liquefaction. The landslides are seen in forests and mountains. Sometimes, fallen trees and sand block the road and the railways. On the other hand, liquefaction is seen at coasts. Because of that, the land subsidence also occurs.

These impacts are very horrible for us. It is difficult to escape from the effects. However, we have to strive to reduce the damage. To keep our peaceful life, we need to find the way.