"INCOIS issues swell surge alert for Kerala, Tamil Nadu, Lakshadweep coasts"
Swell Surge
ocean flooding caused by long-period waves generated by distant storms, not local wind or seismic activity
Peak Wave Period
time in seconds between two successive wave crests; higher values indicate greater wave energy and longer travel distance
India's coastline stretches over 7,500 km, encompassing diverse coastal geomorphologies — sandy beaches, estuaries, lagoons, and rocky headlands — each with varying vulnerability to ocean-driven hazards. The southwestern coast, particularly Kerala and southern Tamil Nadu, faces the open Arabian Sea and is directly exposed to long-distance oceanic energy propagation. The Indian National Centre for Ocean Information Services (INCOIS), headquartered in Hyderabad and operating under the Ministry of Earth Sciences, is India's nodal agency for ocean state forecasting, including tsunami warnings, storm surge alerts, and swell surge advisories. Established under the Indian National Ocean Information Services Centre framework, INCOIS operates the Indian Tsunami Early Warning Centre (ITEWC) and issues real-time ocean hazard bulletins to coastal states.
The Disaster Management Act, 2005 provides the overarching legal framework for coordinating responses to such hazards, establishing the National Disaster Management Authority (NDMA) at the apex level. India is also a signatory to the Sendai Framework for Disaster Risk Reduction 2015–2030, which specifically calls for universal access to multi-hazard early warning systems by 2030. Swell surges, while less catastrophically destructive than tsunamis, represent a recurrent and underappreciated coastal hazard that can cause significant loss of life among fishing communities and coastal tourists — populations that are often inadequately covered by existing warning dissemination infrastructure.
A swell surge is fundamentally different from a storm surge or a tsunami, though all three involve seawater inundating coastal land. Swells are long-period ocean waves generated by distant storms or sustained wind systems operating thousands of kilometres away from the affected coast. Unlike locally generated wind waves (which are choppy and irregular), swells are characterised by their long wavelength, high wave period, and organised, rolling motion — they travel across ocean basins with minimal energy loss. The key metric is peak wave period, measured in seconds between successive wave crests; the current event registered approximately 21 seconds of peak wave period, indicating very high-energy, long-distance swell.
The physics of swell surge coastal impact is governed by shoaling — as deep-ocean swells enter shallower coastal waters, their speed decreases but their height increases dramatically, concentrating energy at the shoreline. …
With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct?
1.OMT is measured up to a depth of 26°C isotherm which is 129 metres in the south-western Indian Ocean during January-March.
2.OMT collected during January-March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.
Which of the statements given above is/are correct?
With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?
1.IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
2.An IOD phenomenon can influence an El Nino's impact on the monsoon.
Select the correct answer using the code given below:
At one of the places in India, if you stand on the seashore and watch the sea, you will find that the sea water recedes from the shore line a few kilometres and comes back to the shore, twice a day, and you can actually walk on the sea floor when the water recedes. This unique phenomenon is seen at
With reference to swell surges, consider the following statements:
1.Swell surges are generated by local wind conditions near the affected coastline.
2.A higher peak wave period (in seconds) indicates greater wave energy and longer travel distance.
3.Low-lying coral atolls are among the most vulnerable landforms to swell surge inundation.
Which of the statements given above is/are correct?
The Indian National Centre for Ocean Information Services (INCOIS) is associated with which of the following?
1.Issuing swell surge advisories for India's coastline
2.Operating the Indian Tsunami Early Warning Centre (ITEWC)
3.Seasonal monsoon rainfall forecasting
Select the correct answer using the code given below:
Consider the following pairs:
Ocean Hazard — Primary Trigger
1.Tsunami — Submarine earthquake or landslide
2.Storm surge — Distant ocean storm generating long-period waves
3.Swell surge — Low atmospheric pressure and strong winds of a nearby cyclone
How many of the above pairs are correctly matched?
With reference to India's coastal disaster management framework, which of the following statements is/are correct?
1.The Disaster Management Act, 2005 established the National Disaster Management Authority (NDMA) chaired by the Prime Minister.
2.The Sendai Framework for Disaster Risk Reduction 2015–2030 calls for universal access to multi-hazard early warning systems by 2030.
3.INCOIS is the nodal agency for cyclone track forecasting along India's coastline.
Select the correct answer using the code given below:
The phenomenon of 'shoaling' in the context of ocean waves refers to:
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