Earthquakes

INTRODUCTION:

Earthquakes are perhaps one of the most frequent and most feared natural hazards around the world. Earthquakes happen almost all around the globe, however they are most frequent near plate boundaries. The earthquakes encircle the whole of the Pacific Ocean, they extend down the entire length of the mid-Atlantic Ocean, and they stretch across southern Europe and Asia, linking the Atlantic and Pacific Oceans. Earthquakes occur in many different scales. One may notice that some earthquakes are of less magnitude than others. Magnitude is the unit of measurement of an earthquake's energy on a Richter Scale. An earthquake with a magnitude of 3 or lower is a less dangeorous arthquake than a earthquake with a magnitude of 7 or higher, which may turn out to be a very destructive and fatal earthquake. There are also other types of scales that measure earthquakes. One such type of scale is called the Mercalli scale. This scale is used to measure intensity of shaking. Earthquakes are so destructive that even if they occur under the ocean they may cause significant damage by resulting into a tsunami and wiping out towns and houses by the caostline. One example of such an earthquake and tsunami due to the water displaced by the earthquake was seen in 2004, when the tsunami wiped out much of Indonesia, and did significant damages in India, Thailand, and Sri Lanka. Earthquakes have been the ultimate weapons of destruction used by the nature for so long, yet the humans have failed to develop anything to stop them or warn people in time before they occur. Humans have always found themselves vulnerable in front of this natural disaster; and their recent contribution to global warmimg and other environmental problems only seems to be complicating the matter further.

CAUSES:

Scientists believe that the major cause of earthquakes is plate tectonics. Plate tectonics is the movement of the plates that make up the Earth's crust. These plates are located above the mantle of the Earth and they rely on convection currents to move them. These convection currents occur in the Earth's mantle and they cause the plates to move 3-4 cm a year. There are two types of crusts that plates consist of. The first type is the continental crust and the second is the oceanic crust. The continental crust is older, lighter, can't sink, and permanent. The oceanic crust is younger, heavier, can sink, and is constantly being destroyed. Plates with one of these two types of crusts form plate boundaries. There are 4 types of plate boundaries, and it is along these plate boundaries where most of the earthquakes happen due to the movement between two plates. The four types of plate boundaries are constructive margins, destructive margins, collision zones, and conservative margins. In constructive plate margins two plates move away from each other. When this happens magma from the mantle rises and cools to form mid oceanic ridges with volcanoes. Gentle earthquakes may occur at this type of plate margin. The second type of plate margin is the destructive plate margin. In a destructive plate margin the Oceanic crust is forced underneath the Continental crust. This happens because the oceanic crust can sink and it is heavier. When the oceanic crust goes underneath the continental crust it forms a subduction zone. Underneath the Continental crust there is hot magma in the mantle which destroys the Oceanic crust. Violent earthquakes happen along this plate boundary due to the increased amount of pressure. The third type of plate boundary is the collision zone. This boundary or zone is formed when two continental plates collide, and since neither can go underneath one another they are forced upwards forming mountains. A classic example of such type of collision zone is the Himalaya Mountains. Earthquakes happen along this zone due to the movement of the plates and due to the pressure. The last type of margin is the conservative margin. In this plate margin two plate move sideways past each other. Land is neither created nor destroyed at this plate margin. However, this plate margin causes violent earthquakes and a classic example is the San Andreas fault in California.

EFFECTS:

The effects of an earthquake may be anything from nothing to devastating. The effect that an earthquake has depends on the magnitude of the earthquake on a Richter Scale. Some earthquakes may be so small that the may go unnoticed. However, other Earthquakes ma be so big and devastating that they may topple houses, cause fires, tear down buildings and skyscrappers, bring down fly overs and bridges, damage roads and other sources of communication, and kill thousands of people. These Earthquakes are usually measured over 7 on a Richter Scale. The effects of an Earthquake also varies on other factors. For example, an earthquake that happens in rural areas where many people don't live will have less effect than an earthquake which happens in a heavily populated city. Other factors that depend on the the effects of an earthquake is whether it happens in a LEDC or MEDC.

AREAS AFEECTED BY EARTHQUAKES:

Earthquakes are a type of natural disater that affect a lot of the areas in the Earth. Earthquakes are generally found near plate boundaries. Earthquakes commonly happen in the Pacific Ocean especially near the Ring of Fire. Earthquakes extend down the entire length of Mid-Atlantic Ocean. They stretch across southern Europe and Asia, linking Atlantic and Pacific Ocean.

PREVENTION:

There are no preventions for earthquakes as of yet. They are just natural disasters that naturally occur. Scientists at the momment are trying to work on how the effect of earthquake can be minimalized if not stopped. Scientists from all around the world are trying to develop early warning systems that detect earthquakes well before they happen so that people can be evacuated from the area before the earthquake strikes.Architects are also trying ti minimalize the effect of earthquakes on lives and building by constructing buildings on rock foundation instead of gravel foundation so that the building doesn't collapse easily. Architects are also constructing buildings that have shock absrobers that absorb the P waves and S waves sent by the earthquake. The buildings are also being built with good suspension, this means that they can sway slightly when the Earthquake happens to avoid being torn down.

LEDC's vs MEDC's:

Earthquakes have differnt effects on LEDC's and MEDC's. Earthquakes that occur in LEDC's are usually more deadly and effective than earthquakes that occur in MEDC"s. There are several reasons behind this pattern. The biggest and most prime reason is that LEDC's are poor and don't have as much money as MEDC's. Due to their weak economy and little budget, LEDC's are unable to buy the right type of equipment to predict an earthquake before it occurs. This causes the people living in LEDC's to be surprised when an earthquake occurs, causing the death toll in LEDC's to be higher than that of MEDC's, because MEDC's have the technology to predict an earthquake or a major movement of plates before it occurs. The other major issue that causes earthquakes to be more deadly in LEDC's than in MEDC's is the communication system. In LEDC's the communication sources are usually very weak. Many areas of a LEDC may not be linked properly by roads or any other type of communication system. Bridges in LEDC's are usually weak, communication by air is hard due to few airports, and construction is generally weak. All these factors sum up to contribute to a destructive earthquake, beacause relief work is hampered in LEDC's due to lack of communication. In MEDC's relief work is done immediatley because of good communication system, modern bridges, quality roads, many airports, and good construction. The other factor that makes the difference is infrastructure. LEDC's usually have houses built of mud and straw. Buildings in LEDC's don't have strong foundation and are built with poor engineering. Wheras in MEDC's the buildings are built with strong foundation and solid engineering causing them to survive earthquakes. The mud houses in LEDC's obviously fail to survive a earthquake and are torn down taking the lives of many people living in them. Other factors are increased corruption, overpopulation, no evacuation plans, and unprepared emergency agencies. All these factors make a normal earthquake worst in LEDC's, whereas in MEDC's the same earthquake may not have half the effect that it had on LEDC's.

WHY PEOPLE LIVE IN EARTHQUAKE PRONE AREAS?

It is very common to see an area devastated by a earthquake, and only after a few months being populated again by people. The big question that rises is, why do people live in earthquake prone areas, even after knowing that there had been a earthquake there before and that it may happen again? One answer to this question may be, because people have nowhere to go. Earthquakes happen in so many places around the globe that they limit the places where one can escape to. Earthquakes have become so common that sometimes they occur in places where they are not predicted to happen. People living in small nations such as Japan can't go anywhere because Japan is a small island and the whole island is affected by constant earthquakes. People just have to live with the threat of earthquakes in Japan because all the Japanese can't move out of Japan and go somewhere else. People live in earthquake prone areas because they have their jobs, businesses, and property there. No one can just leave their jobs and property behind and go somewhere else so easily. The other reason for why people live in earthquake prone areas is because they are poor and they don't have the money to move. Many people living in rural areas can't go anywhere because they can't afford the transportation or in many cases they have no transportation or way to communicate from the outside world. Due to this they are stuck in one place and have to live with the threat of earthquake at the back of their minds.

CASE STUDY: 2001 GUJARAT EARTHQUAKE

CAUSES:

The Gujarat earthquake happened due to the pressure released by plates in a collision margin. The interesting thing was that the collision margin took place far away from Gujarat. A collision margin happens when two contiental plates collide together and since neither can sink they start to fold upwards forming mountains. Due to this the two plates rub against each other creating a lot of pressure. Eventually this pressure was released over Gujarat which is a state in India causing a earthquake in the area. One thing that made this earthquake unique was that it was an intraplate earthquake. There are two types of earthquakes, one is interplate and the other is intraplate earthquake. Interplate earthquakes happen near plate boundaries, however intraplate earthquakes don't occur near plate boundaries but way within a plate itself. These types of earthquakes are very rare and random. They are very hard to predict because the pressure caused by a collision plate margin can be released anywhere, either near the boundaries of the two plates or in the middle of a tectonic plate. The epicentre of the Earthquake was 20km away from Bhuj a town in Gujarat. The epicentre was not near any plate boundary causing it to be a intraplate earthquake.

EFFECTS:

The Gujarat Earthquake was the most powerful and devastating earthquake in the recent history of history. The earthquake was really powerful and it had a magnitude of 7.9 on Richter Scale. Since Gujarat was not next to any plate boundary the area was not prepared for such a big earthquake. This earthquake was so destructive that it killed about 19,727 people and injted over 150,000 people. The earthquake was of such intensity that it destroyed or damaged more than a million structures which included many important historical buildings and tourist spots. The town of Bhuj had to take most of the damage since it was located near the epicentre of the earthquake. The earthquake destroyed tore down many schools and hospitals in Gujarat. The earthquake damaged and destroyed many homes as well. The quake was so severe that big buildings also didn't survive in front of it. Buildings with more thatn 50 floors collapsed one after the other. Total property damage was more that 5.5 billion US dollars.

PROTECTION MEASURES:

After the Gujarat Earthquake the government made a new set of building rules. The government of Gujarat enforced strict policies to make sure that the building rules are followed. One reason for why the Gujarat earthquake was very devastating was due to poor infrastucture and poor building practices. The government of Gujarat worked on strengthening old buildings and ensured that architects followed the building rules. The government also made a long term management plan for the state. According to the plan the government will work on making early warning sytems better. The government also set up a evacuation plan in case of emergency. The governmnet also strengthened the communication system in the state and set up information centres to give people information about earthquakes.

CONCLUSION:

In the future earthquakes may not be as deadly as they are currently. Scientists are working on finding soulutions to earthquakes. Scientists are trying their best to put a grip on nature's most deadliest weapon. Currently scientists have come up with a liquid that they tested by pouring it down a fault. This liquid help lessen the amount of movement between the plates. Scietists are still testing this liquid and trying to make it better. They are also working on improving early warning systems, so that people can be evacuated well before an earthquake strikes. Slowly, slowly the scientists are making progress in controling the earthquakes and minimalizing their affects. In the future scientists may develop a good early warning system, and if that happens the lives of many people may be saved and a lot of the damage will be minimalized. This will not only make earthquakes less destructive but less feared disasters as well. Today science has advanced so much that anything can be done. If scientists find a way in stopping earthquakes or atleast lowering their strength or enegy then earthquakes will become less effective disaster. With the help of modern architecture a lot of nations have already been successful in limiting the damage caused by earthquake. So if we can limit the damage, which was impossible to do 20 to 30 years ago; then we can also stop earthquakes from happening from 20 - 30 years from now.

BIBLIOGRAPHY:

1. "Earthquake." Wikipedia. 15 Nov 2007. 24 Nov 2007 http://en.wikipedia.org/wiki/Earthquake.
2. "2001 Gujarat Earthquake." Wikipedia. 22 Nov 2007. 24 Nov 2007 http://en.wikipedia.org/wiki/2001_Gujarat_earthquake.
3. "Earthquakes." Think Quest. 24 Nov 2007 http://library.thinkquest.org/C003603/english/earthquakes/prevention.shtml.
4. "Gujarat Earthquake Reconstruction and Rehabilitation Policy." 24 Nov 2007 http://www.gsdma.org/pdf/Earthquake%20Rehabilitation%20Policy.pdf.
5. "Plate Tectonics, the Cause of Earthquakes." 24 Nov 2007 http://www.seismo.unr.edu/ftp/pub/louie/class/100/plate-tectonics.html.
6. Waugh, David. The New Wider World. Second. Delta Place, UK: Nelson Thornes Ltd, 2003.
7. Some obvious information from my head!