Earthquake hits China

Context:

•   At least 127 people have been killed in north-west China in the country's deadliest earthquake for years.

What is Earthquake?

1. Sudden release of energy in Earth's crust, causing ground shaking.
2. Natural causes of earthquakes include:
   1. Tectonic Movements: Earth's crust is divided into tectonic plates that constantly shift and interact. When these plates collide, separate, or slide against each other, accumulated stress is released as seismic waves, leading to earthquakes.
   2. Volcanic Activity: Movement of magma beneath the Earth's surface or the collapse of volcanic material during an eruption can generate seismic activity.
3. Anthropogenic causes of earthquakes include:
   1. Mining and Extraction Activities: Digging and extraction processes can weaken the Earth's crust, altering stress distribution and potentially inducing seismic activity.
   2. Reservoir-induced Seismicity: The creation of large reservoirs behind dams can increase pressure on the Earth's crust. This pressure can induce seismic events, particularly in regions prone to this phenomenon.
   3. Nuclear Tests: Detonating nuclear devices underground can generate seismic waves, causing small to moderate earthquakes, depending on the explosive yield and depth of the test.

Measurement of Earthquake:

1. Richter Scale: Measures the magnitude of an earthquake based on the amplitude of seismic waves.
2. Mercalli Scale: Earthquake intensity measures the effects and impact of an earthquake at different locations.It assesses the observed shaking and resulting damage to people, buildings, and the environment.

Irony of Mitigation Measures:

1. Japan and Pakistan experienced massive earthquake in the year 2005.
2. Japan (7.9 Magnitude) Implemented effective mitigation measures and resulted in zero casualties despite a significant magnitude.
3. Pakistan (7.1 Magnitude), on the other hand, lacking similar mitigation efforts resulted in a tragic toll of approximately 1 million deaths.

Mitigation Measures include:

1. Early Warning Systems: Japan utilized advanced detection systems during the Tōhoku earthquake.
2. Building Resilient Infrastructure: Tokyo's Skytree stands as an example of fortified construction.
3. Community-Based Disaster Risk Reduction: California conducts regular earthquake drills for preparedness of people. Also, Nepal's "Community-Based Earthquake Risk Reduction Program” ensures Preparedness-awareness-participation of people.
4. International Collaboration: Centers like the Pacific Tsunami Warning Center facilitate global cooperation.
5. Disaster Response and Recovery Plans: Involve strategies like temporary housing and repair of infrastructure to facilitate recovery. 

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