Saturday 14 April 2012

DISASTER MITIGATION-EARTHQUAKES

EARTHQUAKE:

We all know what earthquakes are, how they affect the life on Earth and we all have also seen many live incidents happening everyday across the world. This makes Earthquakes one of the deadliest disasters of all times. How can we prevent ourselves from damage when an earthquake occurs? Or can we really prevent ourselves from damage when an earthquake occurs? Read On.

Formalities first, what exactly as in scientifically is an earthquake?

The Earth has plates in its magma called tectonic plates that are floating. Earthquakes are caused when tension is released from the rocks in the Earth's crust and upper mantle. Now, this tension is due to the friction between the tectonic plates. Another reason for the earthquakes is when the rocks in the Earth's crust bend and break. This causes shock waves to travel onto the Earth's surface and results in widespread destruction.

Earthquakes usually occur in faults, a place where two tectonic plates meet. Earthquakes are mostly generated deep within the earth's crust, when the pressure between two plates is too great for them to be held in place. The rocks under the earth collapse,which sends shock waves in all directions. These are called seismic waves. The origin of an earthquake under the earth is called the focus of the earthquake.The point on the surface at which an earthquake originates is called the epicentre.

Too much of technicality right?

Onto some interesting facts about earthquakes,

· One of the  world’s deadliest  earthquake  occurred Central China in 1556. It occurred in  a region where most of its people lived in caves of soft rock. These caves collapsed and killed more than 8,30,000 people.

· The earliest recorded evidence of an earthquake has been traced back to 1831 BC in the Shandong province of China, but there is a fairly complete record starting in 780 BC during the Zhou Dynasty in China.

· When the Chilean earthquake occurred in 1960, seismographs recorded seismic waves that traveled all around the Earth. These seismic waves shook the entire earth for many days! This phenomenon is called the free oscillation of the Earth.

· Most earthquakes occur at depths of less than 80 km (50 miles) from the Earth’s surface.

· Each year the southern California area has about 10,000 earthquakes. Most of them are so small that they are not felt. Only several hundred are greater than magnitude 3.0, and only about 15-20 are greater than magnitude 4.0. If there is a large earthquake, however, the aftershock sequence will produce many more earthquakes of all magnitudes for many months.

The world’s greatest land mountain range is the Himalaya-Karakoram. It countains 96 of the world’s 109 peaks of over 7,317m (24,000 ft). The longest range is the Andes of South America which is 7,564km (4700 mi) in length. Both were created by the movement of tectonic plates. 




This picture the right posture to hide.


Earthquake preparedness : 
    • To be prepared for a natural disaster is the most important thing in areas which are prone to them. 

                   Here are a few mitigation methods and ways to be prepared in case of an earthquake.
  • Community preparedness : Community preparedness is vital for mitigating earthquake impact. The most effective way to save yourself is ‘DROP, COVER and HOLD’. 
  • Planning: The Bureau of Indian standards has published building guidelines in areas of high risk. These planning rules are formulated so that the building can withstand the effect of a quake. 
  • If you are inside a building during and earthquake then move to corners or side walls. Try taking cover under a desk/table. Move away from window glass or anything that is liable to break and fall( chandeliers, fans, etc. ). 
  •  If you are on a vehicle, stop the vehicle and move to open lands. 
  • If you are outside then stay away from buildings, walls, power lines and other objects that could fall. Try finding open spaces to stand. 
  • After an earthquake, it is advised to stay calm and follow instructions of the rescue team. Try helping the rescue team to find people who are buried or those who need first-aid after you have got yours.

                            There are many possibilities where a person is when earthquake occurs. Some of the possibilities are described below: 
  • The person might be inside a building or the person might be standing outside somewhere or the person must be driving or the person might be in a mountainous area or a person might be in beach. 
  • A plain area is the best area to be when an earthquake occurs. When the person is inside a building, it is better to hide under a heavy table and hold it. If the building is like a hotel, then it is better to go below the bed and be in foetal position and is better to keep away from windows. It is better to have pillows over the head to prevent head injuries. It is also not advisable to get down in steps because the steps might collapse easily in earthquakes. 
  • When the person is outside the building it is better to stay away from large buildings and power lines because they have the possibility of falling down. If the person is inside a car, it is better to stay inside the car itself and avoid travelling on bridges which has a high risk of getting collapsed. But being inside the car also has a great risk since if there are some roads that are above the place where the car is being parked, it might collapse and fall on the car and the car might get crushed. 
  • If the person is in some mountainous area, there is high risk since the rocks and trees might fell down at any instant. It’s better to stay away from high trees and rocks. If a person is in some seashore, it is better to move to a high lands since there is possibility of tsunami when an earthquake occurs inside the ocean. 
  • After an earthquake has happened, the electric and gas connections must be checked thoroughly. Since, if there are some damages to the gas cylinders there is a risk of explosion of the cylinder which causes heavier destruction. The buildings must be checked for cracks and further damages. If there is huge crack in many parts of the buildings, it is better to get away from the buildings. It is not advisable to go near the seashores since there is risk of tsunami even after a long time after earthquake. 





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