No Tsunami Threat to India

General Studies Paper – 1

Context: Indian Tsunami Early Warning Centre (ITEWC) stated that there is no tsunami threat to India following the Tsunami in Japan.

Tsunami:

• Tsunami (a Japanese word that means “harbor wave”) is a series of giant ocean waves caused by earthquakes or volcanic eruptions under the ocean.
• The formation of a tsunami can depend on a host of factors, including the shape of the ocean floor, and the earthquake’s distance and direction.
• The speed of a tsunami depends on the depth of the water it is traveling through. The deeper the water; the faster the tsunami.

Causes of Tsunami

• Earthquake: When an earthquake takes place under the ocean, a large chunk of the ocean floor can suddenly move upward or downward, leading to a sudden displacement of a large volume of water, thereby causing tsunami waves.
• Volcano eruption: When a volcano erupts in the ocean, the lava flowing out of the volcano displaces the water around it and that water can become a large wave.

How are tsunamis detected?

• Seismic Networks: When an earthquake occurs, seismic networks provide information about an earthquake’s location, depth, magnitude, and other source characteristics. The warning centers analyze this information to determine if the earthquake could have generated a tsunami and if a tsunami message is necessary.
• Water-Level Networks: If an earthquake meets certain criteria, the warning centers turn to water-level information, looking for changes in water-level height that could indicate the existence and size of a tsunami.
• The primary sources of information about water-level change are a network of Deep-ocean Assessment and Reporting of Tsunami (DART) systems and an extensive array of coastal water-level stations.

Consequences of Tsunami

• Loss of Life: Tsunamis can cause significant loss of life, especially in densely populated coastal regions.

In 2011, Japan was hit by a 9.0 magnitude earthquake and a resulting tsunami which killed around 18,000 people

• Major Accidents: The 2011 tsunami in Japan led to a nuclear meltdown at the Fukushima power plant, causing one of the most severe nuclear accidents.
• Displacement of Communities: People living in coastal areas are forced to evacuate or relocate which can lead to temporary or long-term homelessness and strain on resources.
• Infrastructure Disruption: Tsunamis can damage critical infrastructure such as roads, bridges, ports, and utilities, disrupting transportation and communication networks.

Why is Japan prone to earthquakes and tsunamis?

• Japan is situated along the ‘Pacific Ring of Fire’, which is the most active earthquake tectonic belt in the world.
• The ‘ring’ refers to “an imaginary horseshoe-shaped zone that follows the rim of the Pacific Ocean, where many of the world’s earthquakes and volcanic eruptions occur,”
• Within the Ring of Fire, there are different tectonic belts, including the Pacific Plate, Eurasian Plate, and Indo-Australian Plate, which keep meshing and colliding with each other, causing earthquakes, volcanic eruptions and tsunamis.