What are Earthquakes

What are Earthquakes

ABHINAYA BHURTEL, KalimNews: Earthquakes are one of the most dangerous and destructive natural hazards. It is not yet possible to forecast or predict the occurrence of an Earthquake. Earthquakes generally occur without warning. It is a natural phenomenon, which take place due to the movement of the earthquakes.

An earthquake is a sudden shaking or vibration in the earth’s crust. The point of origin of an earthquake inside the earth is called Focus and the point on the surface vertically above the focus is the epicenter.

The energy released from the focus due to elastic rebound of rocks is transmitted in all directions towards the earth’s crust, thus leading to earthquakes. The worst affected area on the surface of the earth is the area between the radius's of epicenter to the Focus.

Magnitude

The magnitude of an earthquake defines the energy released by the even and the intensity of the earthquake depends on the particular place where it is measured. The intensity decreases as the distance from the epicenter increases. The energy or the magnitude of the earthquake is measured on an open ended Richter scale from I to 9. While the seismic energy is recorded on an instrument called seismograph.

Causes

The upper layer of the earth is made up of blocks of rocks. These blocks of rocks float on a layer of semi-liquid rock, called the mantle. Earthquakes occur when the blocks of rocks touch or move against each other, in the semi-liquid layer. This causes a sudden slipping of the portion of the earth’s crust or tectonic plates relative to each other along the fault lines. This movement causes vibrations. At the time of the Assam earthquake in 1897, the Chedrang fault shifted along a dozen kilometers of its length.

Volcanic activity is another cause of earthquakes. An explosive eruption often causes tremors in its vicinity. Sudden landslides and collapse of cavern roofs are other minor causes of earthquakes.

Effects

Earthquakes may cause changes in the earth’s crust of surface. Tremors often set landslides often block the rivers in this region causing floods in the nearby areas. The rivers may change their courses.

The collapse of buildings is the major effect of earthquakes, which often take a heavy toll of life. Dams on river may crack or collapse. Railway lines often twist due to the high magnitude of earthquakes. Roads are often broken. The pipeline supply of water in the urban areas is also severely affected during earthquakes.

An earthquake, which originates under the sea, causes great disturbances to it. The huge waves caused as a result of earthquake, known as TSUNAMIS, cause great loss to life in the costal regions. Tsunamis are common along the coast of Japan.

Earthquake Prone Areas

Certain parts of India are very vulnerable to earthquakes. The Himalayas are young folded mountains. The entire Himalayan region and the subterranean areas of the Himalayas are geologically active and hence more prone to earthquakes. This makes it a high-risk zone.

The region of Maharashtra from Latur through Koyna, Ahmedabad and Delhi to Uttarkashi is also another earthquake prone region.

Although the peninsular block of India is stable, yet certain parts of the plateau are vulnerable to earthquakes.

Preparing For Earthquakes

The people living in the earthquake risk zones should be educated and made aware so that they can take precautionary measures before and after the earthquakes.

The quality of construction is very important to ensure that building is safe. Building designs must be such as to ensure that building until has adequate strength and will remain as one unit when subjected to vibrations, otherwise it will suffer damages.

To make buildings earthquake-resistant, the building byelaws are to be religiously adhered to during new constructions.

The riverbanks in the earthquake prone areas need to be strengthened by building dykes.

In hilly areas lighter material should be used for building houses. Most of the houses should be made of wood or thatched material.

During Tremors

Earthquakes give no warning at all. Sometimes, a loud rumbling sound might signal its arrival a few seconds ahead of time. Those few seconds could give you a chance to move to a safer location. Here are some tips for keeping safe during a quake.

Take cover. Go under a table or other sturdy furniture; kneel, sit, or stay close to the floor. Hold on to furniture legs for balance. Be prepared to move if your cover moves.

If no sturdy cover is nearby, kneel or sit close to the floor next to a structurally sound interior wall. Place your hands on the floor for balance.

Do not stand in doorways. Violent motion could cause doors to slam and cause serious injuries. You may also be hit be flying objects.

Move away from windows, mirrors, bookcases and other unsecured heavy objects.

If you are in bed, stay there and cover yourself with pillows and blankets

Do not run outside if you are inside. Never use the lift.

If you are living in a kutcha house, the best thing to do is to move to an open area where there are no trees, electric or telephone wires.

If outdoors:

Move into the open, away from buildings, streetlights, and utility wires. Once in the open, stay there until the shaking stops.

If your home is badly damaged, you will have to leave. Collect water, food, medicine, other essential items and important documents before leaving.

Avoid places where there are loose electrical wires and do not touch metal objects that are in touch with the loose wires.

Do not re-enter damaged buildings and stay away from badly damaged structures.

If in a moving vehicle:

Move to a clear area away from buildings, trees, overpasses, or utility wires, stop, and stay in the vehicle. Once the shaking has stopped, proceed with caution. Avoid bridges or ramps that might have been damaged by the quake.

After Tremors

After the tremor subsides, it is our social obligation to help those who may have suffered injuries. We should immediately inform the police control room, the fire control office, the near by Red Cross office or the NGOs in the area.

It is also our duty to look for those unfortunate people, who are trapped inside the buildings and rescue and provide first aid to them and if the injuries are of a serious nature they may be shifted to the nearby hospital

For the people whose houses and property have been damaged or have suffered injuries relief camps may be arranged either by to government agencies or other social groups. You as social people should also approach such camps and offer your services.