News Excerpt:

The Indian National Centre for Ocean Information Services (INCOIS) forecasted that high sea waves, also known as swell waves, might hit the coastal areas of Goa, Maharashtra, West Bengal, Odisha, Tamil Nadu, Kerala, Lakshadweep, Karnataka, Gujarat, and Andaman & Nicobar Islands.

More about the news:

• Earlier swell waves had inundated coastal areas in central and southern Kerala, giving anxious moments to coastal communities and prompting district-level disaster management machinery to be in alert mode. Swell waves had flooded beaches along the coastal areas in Thiruvananthapuram, Kollam, Alappuzha, and Thrissur districts. 
  • The phenomenon is referred to as ‘Kallakkadal’ locally in Kerala.
• The Indian National Centre for Ocean Information Services (INCOIS) has warned that the sea will be rough near-shore during the swell wave event. It has cautioned fishermen and coastal population and urged for total suspension of operational/recreational activities at beach/nearshore regions.
  

What are swell waves?

• These waves are formed by an ocean swell, hence the name swell surge. A swell is a series of mechanical or surface gravity waves generated by distant weather systems that propagate thousands of kilometres across oceans and seas.
• Swell waves are not generated by local winds blowing near the shore, Instead, they're the result of the interaction of severe storms with a large fetch of water that takes place in the open ocean, thousands of kilometres away from land masses.

Difference between swell waves and tsunamis:

• Unlike swell waves, a tsunami is a series of enormous waves created by an underwater disturbance usually associated with earthquakes occurring below or near the ocean.
• Tsunamis are around 10 times faster than swell waves. Although both swell waves and tsunamis slow down near the coast, the latter hit land at 30–50 km/h.