Tsunami in India – UPSC Indian Geography Notes

Tsunami, which translates to “harbour wave” in Japanese, is a phenomenon triggered by an earthquake or volcanic eruption beneath the sea, giving rise to immense waves. These waves, also referred to as seismic sea waves, stand as one of nature’s most formidable and devastating forces. The catastrophic Tsunami of 2004 in India stands out as the deadliest disaster, claiming the lives of 26,040 people. The subject of “Tsunami in India” holds significance within the UPSC/IAS Exam Geography syllabus, and this article provides an in-depth exploration of the topic.

What exactly is Tsunami?

  • Tsunami Definition: A tsunami is a series of very long-wavelength waves resulting from significant disturbances above or below the water surface or the displacement of a large water volume in vast bodies like oceans or large lakes.
  • Wave Characteristics: Tsunamis, often termed tidal waves, possess extended wavelengths, and notably, their generation is independent of the gravitational influence of the Moon and Sun.
  • Causes of Tsunamis: Tsunamis can be triggered by various events, including earthquakes (e.g., the 2004 Indian Ocean Tsunami), volcanic eruptions (e.g., the 1883 Krakatoa eruption), landslides (e.g., the 2018 Anak Krakatoa collapse), underwater explosions, meteorite impacts, and other phenomena.
  • Impulsive Forces: Tsunamis may arise from impulsive forces generated by marine volcanic eruptions that displace the water column.
  • Submarine Landslides: During submarine landslides, changes in the equilibrium sea level occur as debris slides over the seafloor, leading to the propagation of tsunamis driven by gravitational forces.
  • Extraterrestrial Impact: The most severe tsunamis can result from collisions with extraterrestrial objects colliding with the Earth.

Indian Ocean Tsunami

Tsunami Terminology:
Tsunamis, resembling swiftly rising tides, are commonly called tidal waves. However, scientists refrain from using this term as tides arise from the gravitational pull of the sun and moon, whereas tsunamis result from water displacement.

Trigger Event: The 2004 tsunami was initiated by a colossal earthquake, ranking as the third-largest ever recorded on a seismograph, with a magnitude ranging between 9.1 and 9.3 on the Richter scale.

Unprecedented Faulting: The earthquake’s faulting endured for an extraordinary 8.3 to 10 minutes, marking the lengthiest seismic event recorded. Numerous aftershocks persisted for 3 to 4 months.

Energetic Consequences: The seismic activity unleashed a tremendous amount of energy, purportedly causing a slight wobble in the Earth’s axis and a subsequent shift in its rotation.

Seafloor Disturbance: The earthquake led to a vertical rise of the seafloor by several meters, displacing an immense water volume and generating the destructive tsunami.

Impact on Indonesia: Indonesia, due to its proximity, was the first nation struck by the tsunami, experiencing the highest casualties with approximately 170,000 lives lost.

Tsunami in India

Indian Coastal Preparedness:
While tsunamis have been absent from the Indian coastal region for an extended period, earthquake activity in the North Bay of Bengal has been observed, accompanied by waves.

Government Identifies Vulnerable Areas: The government has compiled a comprehensive list of tsunami-prone regions along India’s eastern coast, including Puri, Kakinada, Machilipatnam, Nizampatnam-Vetapalem, Chennai, Cuddalore-Pondicherry, Rameshwaram, Thoothukudi, Alappuzha-Chavara, and Kochi.

Historical Earthquake and Tsunami: On June 26, 1941, a seismic event with a magnitude of 7.7 to 8.1 struck the Andaman Islands during World War II, resulting in significant damage and up to 8,000 casualties in the Andaman and Nicobar Islands, India, and Sri Lanka. The impact may have extended to Bangladesh, Myanmar, and Thailand.

2004 Tsunami Event: The 2004 earthquake and tsunami, originating in the Andaman Islands, struck the southern coast of the Indian mainland, affecting Andhra Pradesh and Tamil Nadu approximately 2 hours later. Kerala, on the southwest coast, also experienced simultaneous impacts, with two to five tsunamis coinciding with local high tide in certain areas.

Proximity Impact: Due to its proximity to the earthquake’s epicenter, the tsunami rapidly devastated the Andaman and Nicobar Islands, with varying degrees of impact on different islands, from mild effects on the Andaman Islands to catastrophic consequences on Little Andaman and the Nicobar Islands.

Tsunami Early Warning System in India

Indian Tsunami Early Warning System (ITEWS): Established in 2007 by INCOIS, Hyderabad, ITEWS is a collaborative effort involving institutions such as the Department of Space (DOS), the Department of Science and Technology (DST), the Council of Scientific and Industrial Research (CSIR), the Survey of India (SOI), and the National Institute of Ocean Technology (NIOT).

Functional Components: ITEWS comprises a real-time network of seismic stations, tidal gauges, and a 24X7 operational tsunami warning center. Its primary objectives include identifying tsunamigenic earthquakes, monitoring tsunamis, and delivering timely alerts to vulnerable areas.

Real-time Detection Capability: Indian scientists, leveraging ITEWS, can detect major underwater earthquakes in the Indian Ocean in real-time, enabling the issuance of a tsunami warning within 10-20 minutes.

Tsunami Ready Initiatives: Initiatives like Tsunami Ready, implemented in vulnerable coastal towns, enhance the preparedness for cyclones and storm surges, contributing to effective response capabilities.

Population Preparedness Crucial: Despite advanced warning systems, the effectiveness can be compromised if populations are unprepared. Understanding official and natural warning indications, along with immediate and appropriate responses, is imperative for mitigating the impact of tsunamis.


Advanced Prediction System by INCOIS: INCOIS, the Indian National Centre for Ocean Information Services, has introduced a cutting-edge system capable of predicting risks to coastal areas, determining wave heights, and identifying vulnerable buildings in “real-time.” This marks a substantial enhancement in India’s ability to assess and respond to dangers post-tsunami events.

Real-time Assessment Capability: The newly developed system enables real-time assessment, making India the first country to achieve such a capability, as reported by INCOIS, an institution under the Indian Ministry of Earth Sciences.

Enhanced Safety Measures: With this technological advancement, India has significantly improved its preparedness and safety measures against potential tsunami threats.

FAQs on Tsunami in India

Question 1: What do you mean by a tsunami?

Answer: A tsunami is a series of ocean waves with extremely long wavelengths, typically caused by a significant disturbance, such as an underwater earthquake, volcanic eruption, landslide, or meteorite impact. Tsunamis can result in powerful and destructive waves that can impact coastal areas.

Question 2: Which are the Tsunami prone areas notified by GOI?

Answer: The Government of India (GOI) has identified several tsunami-prone regions along the country’s eastern coast. Some of these areas include Puri, Kakinada, Machilipatnam, Nizampatnam-Vetapalem, Chennai, Cuddalore-Pondicherry, Rameshwaram, Thoothukudi, Alappuzha-Chavara, and Kochi. These regions have been acknowledged as having an elevated risk of experiencing tsunamis.

Question 3: What do you mean by the Richter scale?

Answer: The Richter scale is a logarithmic scale used to measure the magnitude of earthquakes. Developed by Charles F. Richter in 1935, it quantifies the energy released by an earthquake. Each whole number increase on the Richter scale represents a tenfold increase in amplitude of seismic waves and approximately 31.6 times more energy release. It is commonly employed to communicate the size and impact of earthquakes.

UPSC Mains Questions

In December 2004, Tsunami brought havoc on 14 countries including India. Discuss the factors responsible for the occurrence of Tsunami and its effects on life and economy. In the light of guidelines of NDMA (2010) describe the mechanisms for preparedness to reduce the risk during such events. [UPSC 2016]

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