Tsunami: Characteristics, Causes, Effects of Tsunami

What is Tsunami?

A Tsunami is a term used to describe a series of giant ocean waves with long wavelengths that are caused due to an unexpected displacement in the ocean. This can happen due to many reasons such as volcanic eruptions, landslides, nuclear tests, earthquakes, and glacier calvings.

A Tsunami generally occurs due to a sudden shift in the ocean’s tectonic plates, usually due to an earthquake. This shifting of the plates causes the water to rise higher above the level of the ocean. Once the Tsunami waves approach the shore, they slow down but still cause extreme environmental damage. The speed of the Tsunami waves is extremely high.

Tsunami UPSC PDF

The largest Tsunami that has been recorded is the one that occurred in Lituya Bay, Alaska, in 1958. The height of these waves was estimated to be 1700 feet, and caused damage to everything within a 5 square mile radius.

Causes of Tsunami

As discussed above, Tsunami is an unexpected and dangerous event that can cause extreme damage to nature & human beings equally. The center point of the Tsunami is the ocean floor, where the tectonic plates get shifted from their original position. Various causes give rise to Tsunami waves such as the ones discussed below.

Causes of Tsunami in Points

• Volcanic eruptions: An extremely powerful underwater eruption leads to heavy disturbance in the seawater and the displacement of the tectonic plates beneath the sea. This gives rise to Tsunami waves.
• Landslides: Whenever there is an earthquake or a volcanic eruption, it creates a disturbance on the earth’s surface and leads to landslides, ice falls and rock falls. These landslides, in turn, disturb the oceans causing Tsunami waves that travel from their original source and cause damage to the surrounding coasts.
• Earthquakes: The most dangerous Tsunami waves are said to occur due to undersea earthquakes. These cause a major shift in the ocean or the sea bed. The tectonic plates, when they experience a movement, disturb the ocean’s activity causing the water level to rise.
• Meteoroids & Asteroids: There have not been too many such instances, but if occurs a meteoroid or an asteroid when falling into the ocean, may cause serious disturbance within the sea and can lead to a Tsunami.
• Nuclear Tests – As we know, a nuclear test has an extremely high capacity to cause damage with heavy explosions. There has been an instance of an occurrence of a Tsunami due to a nuclear test done by the US in 1940 & the 1950s in Marshall Island.

Characteristics of Tsunami

A Tsunami is a natural phenomenon that takes place very infrequently and due to various reasons as discussed above. It has the capability of causing extreme damage if it reaches a higher magnitude. Generally, a Tsunami can be considered non-destructive, being of a smaller magnitude. There are a few characteristics of a Tsunami that can be kept in mind by the aspirants preparing for the prestigious UPSC exam, and can take down notes about Tsunami in English.

• A Tsunami is a series of strong tidal waves generated from the oceans that slow down once they reach the shores.
• When originating from a deep ocean, a Tsunami can have a wavelength of up to 200 kms.
• There can be as long as more than an hour’s difference between two waves.
• There has been evidence that the maximum occurrence of Tsunami waves has been seen in the Pacific Ocean. It usually occurs every 15 years in the Pacific Ocean.
• India faced serious repercussions of the Tsunami that occurred on 26th December 2004.
• The time required for a Tsunami to cover one end of the Pacific Ocean to the other end is just one day.
• The waves that follow the initial wave usually cause more damage.
• The speed of the Tsunami waves is usually higher in shallow waters as compared to deep waters. This is the reason why the effect of Tsunami waves is higher near the coast & less on the ocean.

Types of Tsunami

On the basis of the magnitude, reach, and place of occurrence of Tsunamis worldwide, they can be classified into three different types.

• Local Tsunami: Occurs within a close range of the center point where the original cause of the Tsunami (earthquake/landslide) occurred. It is usually within 100 kilometers.

• Regional Tsunami: Occurs within a range of 100 – 1000 kilometers from the original source.

• Distant Tsunami: Occurs beyond 1000 kilometers from the source of occurrence. As the name suggests, a distant Tsunami gives decent time to warn the surrounding areas but is expected to cause huge damage. It is also called a Teletsunami or ocean-wide Tsunami.

Formation of Tsunami

Tsunamis are typically generated by large undersea earthquakes, volcanic eruptions, or landslides that occur near the coast or in the ocean. When one of these events occurs, it can cause a large amount of energy to be transferred to the water, which can create waves that travel across the ocean.

When a tsunami reaches the shore, it can cause devastating damage to coastal areas. The Tsunami is typically involves three main stages that are:

• Initial disturbance
• Wave propagation
• Amplification

Early Tsunami Warning System

An Early Tsunami Warning System is a system designed to detect the occurrence of a tsunami and issue warnings to potentially affected coastal areas in advance. The Indian Tsunami Early Warning System was developed in response to the devastating tsunami that struck the southern parts of the country in 2004.

The Indian Tsunami Early Warning System includes a network of sensors that are capable of detecting changes in sea level and seismic activity that could indicate the presence of a tsunami. Different organizations have come together to create this initiative which is the first of its kind to introduce quantitative tsunami forecasts.

Areas Prone to Tsunami

Areas that are prone to tsunamis are typically located along coastlines. Some of the areas that are considered to be most at risk for tsunamis include:

• Pacific Ring of Fire: This region encompasses the coasts of the Pacific Ocean and includes countries such as Japan, Indonesia, and the west coast of North and South America. The region is highly prone to earthquakes and volcanic activity, which can trigger tsunamis.

• Indian Ocean: The coasts of countries such as India, Indonesia, Thailand, and Sri Lanka are at risk for tsunamis due to their proximity to subduction zones and fault lines.

• Mediterranean and Aegean Seas: This region has experienced several large earthquakes and tsunamis in the past.

• Caribbean Sea: The region is prone to earthquakes, and several major tsunamis have occurred in the past, including the 1755 Lisbon earthquake and tsunami.

Effects of Tsunami

Aspirants preparing for the UPSC exam need to be thorough with their knowledge of each and every subject and topic. Candidates should jot down notes about Tsunami and understand the topic well. There are a number of hazardous effects of a Tsunami that cause damage to human life & surroundings.

• A large number of people have died due to the sudden onset of a Tsunami.
• There has been an immense loss of property due to the tsunami, and many buildings and public property have been damaged.
• A dreadful and dangerous Tsunami can also cause physiographical changes on Earth, changing the location & size of certain areas.
• As per a recent survey, earthquakes of large magnitude that result in Tsunami waves also cause a major shift in the Earth’s rotational movement.
• The major effect is caused to the marine environment existing underwater as the complete process initiates under the sea. Some of the species may also become extinct & their regular activities may see a major change because of Tsunami.

Tsunami Disaster Management

Considering the amount of hazard attached to the occurrence of a Tsunami, we need to take some serious mitigation measures. We need to adopt certain measures that can help us prevent excessive damage to human life & its surroundings. We can not stop or control the Tsunami waves as they are extremely strong. Some simple steps that can be taken if we are at risk of facing such a Tsunami threat such as –

• Plan more and more trees, such as in a village in Tamil Nadu.
• Appropriate relief and rescue measures should be taken.
• Spread knowledge and awareness among the people.
• We need to stay away from the rivers that lead to the ocean.
• Adopt detailed and advanced planning.

UPSC Notes
Disaster Management	Cyclone Disaster Management
Disaster Management Act 2005	National Disaster Management Authority
Wetlands in India	Landforms
Floods in India	Ocean Currents
Local Winds	Types of Winds