Introduction: What is an earthquake? According to the Qiang Zu, “An earthquake is the result of sudden release of stored energy in the earth’s crust that creates seismic waves

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Introduction:

• What is an earthquake?

• According to the Qiang Zu, “An earthquake is the result of sudden release of stored energy in the earth’s crust that creates seismic waves. Earthquakes are accordingly measured with a seismometer, commonly known as a seismograph. The most common earthquake are tectonic earthquake which are originate at depths. It causes tsunamis. Earthquake locations are mainly determined by the strength of the rocks and the subsurface temperature” (2021). According to Kovach, “Earthquake is a sudden shaking within the earth caused by the release of accumulated strain in the rocks that make up earth’s crust” (2003).

 

• What is tsunami?

• According to the Kovach & Mc.Guire, “ Offshore earthquakes may not cause as much building damage through ground shaking but they can inflict terrible destruction through the generation of the giant sea waves known as tsunami. These are generated when a submarine earthquake imparts a sharp jolt to a large area of sea floor, sending waves radiating rapidly from the source. In deep water, tsunami can travel at velocities more than 800 km/h (500 mph) − meaning, for instance, that they can cross the entire Pacific Basin in slightly more than 20 hours” (2003).

 

• What are the effects of earthquake?

• According to the Kovach & McGuire, “The effect of earthquake is classified as primary, transient and secondary effect. Primary effects are permanent features produced by an earthquake, most notably surface ruptures, scarps, horizontal offsets, changes in ground elevation, offsets of fences and roads and twisted railways. Therefore, it leads to transient effects such as visible ground waves, ground shaking and tsunami, and human reactions such as nausea and panic. Shaking is the main cause of earthquake damage and can last from several to tens of seconds. Transient effects produce secondary effects such as landslides, slumps, lurches, mudflows, avalanches, seiches (oscillations in lakes and other large water bodies) and, most importantly, building damage” (2003).

 

• What is an aftershock?

• According to USGS, “Aftershocks are smaller earthquakes that follow main shocks, and they are caused by adjustments of the fault that broke during the main shock.  They are the seismic equivalent of the fault “creaking” as it settles into a new relaxed state after the main earthquake. When an earthquake occurs, the state of stress around the earthquake dramatically changes” (2020).

 

• How is earthquake measured?

• According to Article, “There are two primary scales used to measure earthquakes. Richter scale and Mercalli scale. Another scales to measure the earthquake is Moment magnitude scale used by some seismologists. These three scales provide useful information in measuring and analyzing earthquakes across the globe” (phillips, 2021).

• • • • The Richter scale: It is calculated based on the amplitude of the largest seismic wave recorded for the earthquake. It is base-10 logarithmic scale. The richter scale runs from 1 to 10. 1 is the smallest and 10 is the largest.

      • The Mercalli Scale: “It Measures the intensity of an earthquake by quantifying the effects of an earthquake on the earth’s surface. Mercalli scale rates earthquakes on a scale of 1 to 12, with 1 denoting the nothing much felt and 12 denote total destructions.

      • Magnitude Scale: It compares energy released by earthquakes and is based on the moment of the earthquake, which is equal to rigidity of the earth multiplied by the average amount of the slip on the fault and the size of the area” (Philips, 2021).

• Body

Background:

• According to the Roback, et all (2018), The 25th April 2015, Nepal experience 7.8 magnitude earthquake and its afterschock triggered about 25,000 landslides over an area of more than 30,000km2 in the greater and lesser Himalaya of Nepal.

• The earthquake was followed by hundreds of aftershocks, and only 17 days later, there was another major quake, a magnitude 7.3 temblor. Thirty-nine of the nation’s 75 districts with a population of 8 million people — about a third of the national population — were affected (Rajendran, et all (2017).

• The local time of earthquake was on 11:56 am. The earthquake occurred at the subduction interface along the Himalayan arc between the Indian plate and the Eurasian plate. The earthquake rupture propagated from west to east and from deep to shallow parts of the shallowly dipping fault plane.  and consequently, strong shaking was experienced in Kathmandu and the surrounding municipalities. This was the largest event since 1934, Mw8.1 Bihar–Nepal earthquake (Dahal, et all 2018).

• According to Dahal, et all (2018), Nepal is the 11th most earthquake prone country in the world.  Due to the earthquake effect, Mental health disturbances, especially post-traumatic stress disorders are major public health issues arising in the aftermath of such natural disasters of higher intensity. It was the deadliest earthquake in the seismically active region in 81 years.

Damages & Hardships

• Over 602,00 houses were destroyed and more than 280,000 were partially damaged. Over 1000 health facilities were damaged and destroyed, while over 100,000 people were displaced into makeshift camps (Aftermath, 2015).

• The 7.9-magnitude earthquake that struck west of Kathmandu, Nepal's capital, on April 25th toppled buildings and crushed the unlucky people inside. (sthapit, 2015).

• On May 12, magnitude 7.3 aftershock occurs, which cause destruction of school, health center, water and power systems, road, bridges along with home (Reid, 2018).

• June to September,2015: Monsoon season rains cause landslides, making mountainous regions inaccessible to foot traffic. Low clouds prevent air operations (Reid, 2018).

 

• The 2015 earthquake triggered an avalanche that killed 19 climbers on Mt. Everest and stranded hundreds at the base camp (Reid, 2018).

• Many survivors lost not only family members but their home and all their possessions. Farmers lost livestock, crops, tools, and irrigation works (Reid, 2018).

• Why was the 2015 Nepal earthquake so destructive?

• According to the world vision, “At nine miles deep, the shallow initial quake caused a lot of shaking near the surface. Poorly constructed multi-story brick buildings and temples in and around Kathmandu were reduced to rubble. Brick is the go-to building material there because the Kathmandu Valley has many brick works” (Reid, 2018).

• Mountainous rural areas with poor infrastructure suffered even worse. Whole villages collapsed; their houses made of stacked stones or timbers and mud were no match for the destructive force of landslides, avalanches, and shaking (Reid 2018).

• Recovery:

• With help from the United Nations, the Government of Nepal, thousands of volunteers and over 450 humanitarian agencies responded to deliver critical life-saving aid to affected communities. The United Nations, donors, international NGOs and the International Federation of Red Cross and Red Crescent Societies immediately mobilized resources and reprogrammed activities. On 29 April, the Humanitarian Country Team launched the Nepal Earthquake Flash Appeal to provide protection and relief to 2.8 million people. Under the Flash Appeal, from April to September 2015, humanitarian assistance reached 3.7 million people (Ovesen & Heiselberg).

• World vision organization trained 65,000 children as well as adult how to reduce their risk in case of disaster and retrofitted community buildings with earthquake-resistant construction (Reid, 2018). They planned 3 years response to the earthquake.

• • • • After three-month, world vision helped:

        • 133,000 people receive relief goods and services such as Child-Friendly Spaces and Temporary Learning Centers, where children attend classes until their schools are repaired or rebuilt (Reid 2018).

      • After six months,

        • 229,000 people affected by the earthquake

        • 17,000 families with emergency shelter kits

        • 96,000 people with the restoration of water and sanitation services

        • 8,200 children, who attended Child-Friendly Spaces and Temporary Learning Centers (World Vision).

      • After 2 years,

        • More than 526,873 people across 10 of Nepal’s hardest-hit districts

        • 28,860 families with shelter assistance, including roofing sheets and toolkits for rebuilding

        • 39,821 children with education assistance through school materials, construction of Temporary Learning Centers, and the rebuilding of 14 schools

        • 114,775 people restore their livelihoods through agriculture training and tools, new livestock, and the repair of 55 irrigation systems

 

 

• Conclusion:

  • • An earthquake is the result of sudden release of stored energy in the earth’s crust that creates seismic waves.

    • They are produced by energy causing shaking around fault lines.

    • The most common earthquake is tectonic earthquake which are originate at depths. It causes tsunamis.

    • Nearly 9,000 people died and more than 22,000 suffered injuries.

    • More than 600,000 homes were destroyed and more than 288,000 were damaged in the 15 worst hit districts.

    • A magnitude 7.8 earthquake strikes. About 100 international search and rescue and medical teams arrive within 24 hours.