BENGALURU: Arguing that India’s west coast, which has so far not been studied seriously for its vulnerability to tsunamis despite multiple events recorded over the years, a new study has found that a major tsunami in the northern Arabian Sea could severely impact the western coastlines of India and Pakistan.
CP Rajendran from the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) in Bengaluru, Mohammad Heidarzadeh from Brunel University, London and their team have found that a magnitude 9 earthquake and consequent high tsunami waves is a possibility in the Makran subduction zone.
The study, which has been published in Pure and Applied Geophysics, Rajendran told TOI, was to understand tsunami hazards of the northern Arabian Sea. The entire northern Arabian Sea region, he says, needs to take this danger into consideration in hazard perceptions.
Rajendran and his team began their study after having found that compared to India’s eastern coast, tsunami hazards on the west coast were under-recognised. This, Rajendran said, despite an 8.1 magnitude earthquake that had occurred in the Makran subduction zone in 1945.
While the study relied on historical reports of a major disturbance that struck the coast of western India in 1524 — recorded by a Portuguese fleet off Dabhol and the Gulf of Cambay — its findings are corroborated by geological evidence and radiocarbon dating of seashells transported inland.
“These are preserved in a dune complex at Kelshi village near Dabhol,” Rajendran said. The team’s modelling showed results suggesting high impact in Kelshi could have been generated by a magnitude 9 earthquake sourced in the Makran subduction zone during the 1508 —1681 period.
Subduction zones occur when one tectonic plate slides over another, releasing seismic energy. He added that as per the radiocarbon dating of the shells, inundation may have occurred during 1432—1681 and overlaps the historical reports of major sea disturbances in 1524.
“These 1524 disturbances were recorded by a Portuguese fleet of 14 ships led by Vasco da Gama,” Rajendran said, further adding that a future tsunami in the Makran subduction zone, therefore, could not only affect Iran, Pakistan and Oman but also devastate India’s west coast.
India has multiple critical facilities, including nuclear plants on its west coast, which would need to be protected in the event of a tsunami.
The 2004 tsunami, which claimed more than 2.5 lakh lives while sweeping clean beaches of Sri Lanka, Indonesia and Thailand had also seen the Kalpakkam nuclear power plant on the coast of Tamil Nadu flooded.
Rajendran says a tsunami of a similar magnitude is more likely to occur on the west coast.