Thiruvananthapuram | The coastal areas of Kerala and Tamil Nadu are likely to experience the "kallakkadal phenomenon," the sudden swell of the seas causing rough waves, on January 15 night, according to an alert issued by a central agency.

The areas are likely to experience waves of upto 0.5 to 1.0 meters until 11.30 pm on the day, and so there is a possible threat of sea surge, according to the Indian National Centre for Ocean Information Services (INCOIS).

In view of the warning from the INCOIS, the agency that issues weather warnings for fishermen in the country, the Kerala Disaster Management Authority (KSDMA) here advised coastal people to shift to safer locations from the dangerous-prone areas as per the direction of the authorities.

Coastal dwellers are advised not to venture into the sea in tiny vessels and country boats and to safely moor their fishing vessels in the harbour, an official statement said.

The authorities also advised avoiding any kind of tourism activities on beaches until the warning is withdrawn.

Extra vigilance should be exercised regarding the dangers of coastal erosion also due to the swell surge, the KSDMA added.

The term 'kallakkadal' literally means a sea that comes suddenly like a thief.

INCOIS has said that the swells result from strong winds in the southern part of the Indian Ocean at certain times, and that they occur suddenly without any particular indications or warning. Hence, the name 'kallakkadal.'