What Is an Earthquake?

Earthquakes occur when stress builds up in the Earth's crust and is suddenly released, usually along a fault line. The point where the energy is released is called the focus, and the point on the Earth's surface directly above it is the epicenter.

Causes of Earthquakes

1. Tectonic Plate Movements:

   • Most earthquakes occur at plate boundaries where plates converge, diverge, or slide past each other.

2. Volcanic Activity:

   • Some earthquakes are triggered by volcanic eruptions.

3. Human Activity:

   • Activities like mining, reservoir filling, and underground explosions can also cause minor earthquakes.

Effects of Earthquakes

• Primary Effects:

  • Ground shaking, which can cause buildings and infrastructure to collapse.

  • Surface rupture, where the Earth's surface is visibly displaced along a fault.

• Secondary Effects:

  • Tsunamis, landslides, and fires caused by ruptured gas lines.

  • Disruption of water supplies, power, and communication networks.

Notable Earthquakes in History

• 2010 Haiti Earthquake:

  • Magnitude 7.0, causing widespread destruction and loss of life.

• 2011 Tōhoku Earthquake (Japan):

  • Magnitude 9.0, leading to a devastating tsunami and the Fukushima nuclear disaster.

• 1906 San Francisco Earthquake:

  • Magnitude 7.9, followed by fires that destroyed much of the city.

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