Syllabus
GS-1: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.
Context: The Indian National Centre for Ocean Information Services (INCOIS) confirmed that there is no tsunami threat to India following the powerful earthquake off the coast of Russia.
More on the News
- A powerful 8.8-magnitude earthquake struck Russia’s Far East on 30 July 2025 IST (29 July, UTC) off the East Coast of Kamchatka.
- It triggered tsunami waves across parts of Russia, Japan, the Pacific Islands, and the US.
About Tsunami
- A tsunami is a series of waves generated by a large and sudden displacement of the ocean.
- Large earthquakes below or near the ocean floor are the most common cause, but landslides, volcanic activity, certain types of weather and meteorites can also cause tsunamis.
- An earthquake is a sudden, shaking or trembling of the Earth’s surface caused by the release of energy in the Earth’s crust.
Key Cause of Tsunami
- Undersea Earthquakes (~80% cases): Most tsunamis are caused by strong earthquakes beneath the ocean floor that result in vertical displacement of the seabed.
- This sudden uplift or subsidence pushes water upward or downward, creating waves that radiate outward rapidly across the ocean.
- Conditions for a Tsunami-Causing Earthquake:
- Undersea Earthquakes (~80% cases): Most tsunamis are caused by strong earthquakes beneath the ocean floor that result in vertical displacement of the seabed.
- This sudden uplift or subsidence pushes water upward or downward, creating waves that radiate outward rapidly across the ocean.
- Conditions for a Tsunami-Causing Earthquake:
- Magnitude: Must be strong enough, usually above 7.0 on the Richter scale.
- Location: Must occur beneath or near the ocean floor.
- Vertical Movement: Must involve uplift or subsidence (not just horizontal shifting).
- Duration and Area: A longer-lasting quake affecting a wider area displaces more water.
- Depth: Shallow-focus earthquakes (closer to the surface) are more likely to generate tsunamis.
- Underwater Landslides: Earthquakes can trigger submarine landslides that also displace water.
- Volcanic Eruptions: Volcanic eruptions and collapsing slopes near or under water can abruptly displace water, triggering tsunamis
- Meteorite impacts into oceans or seas.
- Glacier calving (sudden large ice chunks falling into the sea) in polar regions.
Indian National Centre for Ocean Information Services (INCOIS)
- It was established as an autonomous body in 1999 (Hyderabad, Telangana) under the Ministry of Earth Sciences to specialise in early alerts for ocean-related hazards.
- It provides round-the-clock monitoring and warning services for the coastal population on tsunamis, storm surges, high waves, etc. through the in-house Indian Tsunami Early Warning Centre (ITEWC).
- The Intergovernmental Oceanographic Commission (IOC) of UNESCO designated ITEWC as a Regional Tsunami Service Provider (RTSP) to provide tsunami warnings to countries on the Indian Ocean Rim.
- INCOIS has been designated as the ‘National Oceanographic Data Centre’ by IOC/IODE of UNESCO and is also identified as the ‘Regional Argo Data Centre for the Indian Ocean’.
- INCOIS is a permanent member of the Indian delegation to the IOC of UNESCO and a founding member of the Indian Ocean Global Ocean Observing System (IOGOOS) and the Partnership for Observing the Oceans (POGO).