The Times of India, Paul Fernandes, TNN, Mar 25, 2011
PANAJI: The unusual flooding of Morjim and Baga beaches showed signs of respite on Thursday, but a tsunami expert said it may have been caused by a meteo-tsunami on the lines of a similar phenomenon in Kerala during the past decade.
"There were no strange meteorological disturbances seen on the state's coastline," the source said. There was no depression in atmospheric pressure nor was the wind abnormally strong, though it blew in gusts and may have contributed partly to the flooding.
"It appears that a wave from a storm far in the sea travelled a long distance to the state's coast," the source said. A similar phenomenon, which local people in Kerala mistakenly thought was a tsunami, had hit the southern state's Poonthura coast in May 2005, April 2007 and February 2008.
Referred to as 'kallakkadal' (literally sea surges in unnoticed like a thief) by Kerala fishermen, the flooding of the coast that followed has been documented in international journals, sources said.
The impact of flooding is more intense when it occurs on supermoon spring tides. "The case of Baga and Morjim was one such, and it was caused by wave set up" the source said. The sea water level rise showed signs of receding in Baga on Thursday.
"The water level rose seven metres on Tuesday, five metres on Wednesday but only three metres on Thursday," shack owner Mario D'Souza said.
"We had never seen anything like this earlier," Morjim shack owner Jenny Madeira told TOI.
Though the impact and destruction caused by geophysical tsunamis has evoked fear globally, the impact of meteo-tsunamis is lesser known, yet they can cause havoc on a smaller scale in fewer locations.
"The event in Baga and Morjim, unlike Kerala, may be a new event," the source said.
The flooding events and detailed accounts of meteotsunamis in the world has been provided by NIO scientist Anthony Joseph in his book, "Tsunamis: Detection, monitoring and early-warning technologies", published in February 2011.
Huge sea waves on the coast or meteorological tsunamis are caused by atmospheric gravity waves, atmospheric pressure jumps, wind waves and other factors, but may result in less impact.
"Other mechanisms that may result in a meteo-tsunami include tide-generated internal waves, wave superposition, wind-current interaction, wave-current interaction and atmospheric shockwaves (say, from volcanic activity)," the source added.
The atmospherically generated ocean waves, whose origin remains shrouded in mystery, have been observed in recent sea-level records from coasts, among others, of the Adriatic Sea, English Channel, and Washington (USA) and notoriously in several locations in the Mediterranean Sea.
"Meteo-tsunamis some times closely resemble rogue waves, freak waves, or giant waves," the source said. The sea enters land without any meteorological disturbances and no warning signs.
