Earthquake and Flood

Earthquake

When there is a sudden release of energy in the Earth's crust, it creates a seismic wave that results in the sudden shaking or vibration of the Earth's crust or surface. This shaking or vibration of the crust or surface of the earth is known as an earthquake. It does not occur frequently but it occurs suddenly without warning causing huge destruction of life and human properties. Earthquakes makelong cracks in the earth's surface called fault lines and can be felt over large areas. Although they usually last less than one minute. We cannot predict the earthquake but also scientists are working on it. There are about 500,000 earthquakes a year around the world, as detected by sensitive instruments. Out of them about 100,000 of those can be felt, and 100 or so cause damage each year. The largest earthquake ever recorded was a magnitude 9.5 in Chile on May 22, 1960. Depending upon the type of movement, Earthquakes are of two types, they are horizontal Earthquake and Vertical Earthquake.

A British Seismologist named John Milne invented an instrument called Seismograph that is used to records the shaking of the Earth's surface. The Earthquake is measured in Richter Scale. The Seismograph measures the Earthquake waves from the range between 0- 9 Richter Scale. The Earthquake more than 6 Richter scale is very destructive. The point inside the surface of the earth through which Earthquake origin is known as Hypocenter. It is always below the earth's surface and most of the Earthquakes have their epicenter at a depth of less than 60 km. Similarly, the point on the surface of the Earth just above the hypocenter is knowns as Epicenter. The magnitude of Earthquake is found more in the epicenter.

Earthquake is very dangerous. It destructs the human properties. Earthquake does not kill any people or wildlife but people are killed by their constructions during the earthquake. Earthquake inside the seas or ocean causes tsunami and also it causes volcanoes that cause great loss of life and property. This damage can be minimized by better construction, safety systems, early warning, and planning.
Recently, Nepal was hit by the devasting Earthquake of 7.8 Richter scale on 12^th Baisakh 2072. The epicenter was Barpak village of the Gorkha district. During this disaster, more than 8,800 people were killed and millions of people were homeless. This disaster badly affects western and central region of Nepal especially in hilly and mountain region. This cause huge loss of life and human properties. Many old buildings including World Heritage like Basantapur Durbar Square, Swayambhunath Stupa were destroyed. It also causes a huge avalanche in Langtang valley killing hundreds of people and some in the mountain region. The Earthquake of 6.9 Richter Scale in 2045 BS was felt in Nepal. The Nepal was also hit by the massive Earthquake in 1990 BS.

Causes of Earthquake

Some of the causes of Earthquake are discussed below,

• Tectonic Forces: The crust of the Earth is divided into several mega plates. These plates are known as continental plates. They are in continuous motion. Sometimes they move towards eachother and sometimes away from eachother due to the tectonic force generated inside the surface of the Earth. The movement of this place causes them to bend, fracture and overlapping which results into an earthquake.
• Volcano Eruption: Volcano is also considered as the causes of Earthquake. During volcano eruption, the inside content of the earth like rocks, magma, etc comes out from the earth crust. They come out forcefully affecting the continental plates and causing vibration on the surface of the Earth.
• Mine Blast and Nuclear Tests: Various projects and works are carried out by developed and powerful countries like mine blast and nuclear tests. These activities create pressure on the internal part of the Earth and cause contraction and expansion of the rocks and movement of liquid and gasses inside the earth causing movement of the surface of the earth.

Effect of Earthquake

• Destroys life and human properties and constructions like buildings, bridges, canals, etc.
• Damages the transportation systems, communication systems, etc.
• Damages old house and cultural heritages.
• Causes flooding, avalanche, and landslide.
• When Earthquake occurs inside the oceans, it causes the tsunami.
• Causes Glacial Lake Outburst Flood in the Himalayan Region.
• It may cause cracks in the crust.

Safety Precautions for Earthquake

We cannot stop Earthquake from coming. We can't get any warnings before the Earthquake. But we can be minimized the effects of Earthquake. The effects of Earthquake can be minimized in various ways which are discussed below in three topics,

Before an Earthquake

• We should not put heavy furniture, mirrors, etc near our beds.
• We should set up family meeting location in a safe area.
• Awareness programs should be created about the effects of Earthquake.
• We should put an emergency bag with nonperishable food, water, first aid supplies, flashlights etc.
• We should secure items that may be vulnerable to shaking.

During an Earthquake

• We should not stay near furniture and windows.
• We should immediately turn off the gas and electricity if possible.
• We should stay in open areas that if free of buildings, power lines, towers and other potential hazards.
• We should stay in a safe place like under the desk or table by covering our head and neck with our hands.
• If we are driving then we should stop our vehicle. Do not stop near power lines, bridges, overpass etc.

After an Earthquake

• We should be aware of aftershocks. It can last for few days or months.
• Injuries should be immediately treated and given health assistant.
• We should turn off gas, electricity and water supply.
• We should immediately rescue the people who are trapped in Earthquake.
• We should keep our phone lines clear for emergency use.
• We should not enter the damaged building.

Flood

When the amount of water in the river increases due to over rainfall or over the melting of snow, the water gets overflow and submerges the land. This is known as flooding. It is very dangerous. It destroys land, crops, animals and life. It sinks the whole city or village area. Some floods occur suddenly and stop quickly whereas some stops after few days or month. Flood carries along objects like houses, animals, cars, furniture, some peoples etc. It can wipe away farms, trees, and much more heavy items. It is a common natural disaster and occurs in those areas where there is more rainfall. The most deadly flooding occurred in 1931 in China and killed about 2,500,000 people.

Causes of Flood

Some of the causes of flood are discussed below,

Rain: When there is excessive rainfall in a short period of time, then it causes a flash flood. When there is small rainfall for a longer period of time then it increases the level of water in river causing flooding in the river.

River overflow: Due to some reasons, the river can overflow from their normal path causing a flood. Some of the reasons for the overflow of the river from the normal path are like an increase in the amount of water, some obstacles blocking the passage of water, etc.

Dam breaking: Various dams are made to hold up water for the generation of electricity. Sometimes, too much water held up in the dam cause it to break and overflow the area. Some of the reasons for the breaking of the dam are also like weak support, some natural disaster like earthquake, landslide etc. The breaking of dam let the massive flow of reserved water causing a flood.

Precaution before a Flood

• We should construct barriers or walls at the both sides of the river to prevent overflow of the river.
• The government should warn the people if there is the possibility of coming flood.
• We should not construct houses near rivers or in a floodplain area.
• We should immediately move to higher ground if there is the possibility of a flash flood.
• We should be mentally and physically prepared.
• Awareness programs should be created about the flooding.

Precaution during the Flood

• We should not walk through a moving water.
• We should move to higher places during flooding.
• We should not drive in flooded areas.
• We should turn off the electricity and do not touch the electrical equipment if we are wet or standing in water.

Precaution after the flood

• We should clean our environment after the flood.
• We should remove floodwater as it is contaminated by sewage and harmful materials
• We should repair damaged septic tanks, cesspools, pits, etc as soon as possible.
• We should return to our area if it is declared as a safe place.

Preventive Measures of Flood

• We should plant trees on both sides of the river.
• Deforestation and overgrazing should be stopped.
• We should construct a wall on both sides of the rivers.
• The direction of flow of water of river must be fixed in only one direction.