Daily Mains Question – GS 1 – 12th August 2025
- TPP
- Aug 12
- 4 min read
Welcome to your daily UPSC Mains Answer Practice! Today’s question explores the powerful geological processes that underpin one of the most destructive natural disasters — tsunamis — with a specific focus on the recent 2025 Kamchatka earthquake. This event, marked by an 8.8 magnitude undersea quake off Russia’s Far Eastern coast, triggered tsunami waves reaching up to 5 meters and prompted alerts across the Pacific Basin. The question provides a platform to examine how specific tectonic settings — particularly subduction zones involving reverse faulting — play a critical role in tsunami generation. Understanding these mechanisms is essential for GS Paper 1 – Geography, particularly within the themes of geomorphology, plate tectonics, and disaster-prone regions. In an era of increasing coastal vulnerability, analysing such seismic phenomena offers crucial insight into hazard assessment, disaster preparedness, and sustainable coastal planning.
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QUESTION
Examine the geological and tectonic conditions under which undersea earthquakes generate tsunamis. Illustrate your answer with reference to the recent Kamchatka earthquake.
Answer: Tsunamis are long-wavelength sea waves typically triggered by sudden vertical displacements of the seafloor, commonly due to undersea earthquakes. On April 10, 2025, a massive magnitude 8.8 earthquake struck off the Kamchatka Peninsula in Russia’s Far East, generating tsunami waves up to 5 meters (approx. 16 feet) high. The seismic event triggered tsunami alerts across the Pacific Rim, affecting nations such as Japan, the United States (Hawaii and California), Ecuador, and Peru.
This event underscores the link between tectonic activity and tsunami generation, particularly along convergent plate boundaries, where large-scale subduction and reverse faulting are common.
Geological and Seismic Factors Responsible for Tsunami Generation
1. Tectonic Plate Boundaries and Earthquake Genesis
The Earth's lithosphere is divided into tectonic plates that move over the asthenosphere.
Most earthquakes originate along plate boundaries, especially convergent boundaries, where an oceanic plate subducts beneath a continental or another oceanic plate.
The Kamchatka Peninsula lies along the Kuril-Kamchatka Trench, a highly active subduction zone where the Pacific Plate is being thrust beneath the Okhotsk Plate at a rate of ~86 mm/year, one of the fastest in the world.
2. Fault Mechanism – Reverse/Thrust Faulting
The Kamchatka earthquake was caused by reverse faulting, where the overriding plate is pushed upward due to compressional forces.
Reverse faults are particularly conducive to tsunami generation as they lead to sudden vertical displacement of the seafloor, which in turn displaces a massive volume of water, initiating a tsunami.
According to the USGS, reverse faulting is the most common seismic mechanism associated with significant tsunamis.
3. Magnitude and Depth of the Earthquake
The magnitude of the earthquake was 8.8, which is significantly higher than the 7.0 magnitude threshold often associated with tsunami generation.
The focal depth was shallow, at 19.3 km, allowing more seismic energy to reach and disturb the seabed.
Shallow-focus earthquakes (<70 km depth) are more effective at transmitting energy to the seafloor compared to deeper quakes.
4. Sudden Vertical Displacement of the Seafloor
The NOAA identifies sudden vertical motion (uplift or subsidence) of the ocean floor as the primary trigger for tsunamis.
In the Kamchatka event, uplift of the seafloor caused by reverse faulting generated a massive column of water that was displaced outward in all directions.
5. Tsunami Wave Characteristics
Tsunamis travel at speeds of 500–900 km/h in deep ocean waters, with wave heights increasing as they approach shallow coastal areas due to wave shoaling.
The Kamchatka-induced tsunami propagated rapidly across the Pacific Ocean, with wave amplitudes increasing upon reaching coastlines like Hawaii and Northern California.
Kamchatka Earthquake: A Case Study
Feature | Data |
Magnitude | 8.8 (Moment Magnitude Scale) |
Depth | 19.3 km (shallow-focus) |
Fault Type | Reverse Faulting |
Tectonic Setting | Subduction of Pacific Plate beneath Okhotsk Plate at Kuril-Kamchatka Trench |
Tsunami Waves | Up to 5 meters (16 feet) |
Tsunami Alerts | Pacific Basin: Japan, USA, Indonesia, Peru, Ecuador, Colombia |
The Kamchatka earthquake is a textbook example of how undersea reverse faulting, shallow depth, and high magnitude earthquakes in subduction zones lead to tsunami generation. With an accelerating pace of urbanization in coastal zones and the increasing impact of climate-related vulnerabilities, understanding the geophysical dynamics of earthquake-induced tsunamis is crucial for effective disaster preparedness, early warning systems, and coastal hazard mitigation.
Way Forward
Strengthening real-time seismic and tsunami monitoring systems (e.g., DART buoys, GPS-based crustal motion detectors).
Improved coastal land-use planning in tsunami-prone zones.
Conducting community awareness programs and periodic evacuation drills.
Enhancing international cooperation in Pacific and Indian Ocean tsunami warning frameworks.
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