Scientists admit that tsunamis cannot be predicted with certainty

Tsunami was lesser-known and therefore lesser-feared, until the gigantic tragedy that struck areas lying in the Indian Ocean region in December 2004. While the devastation has been widely chronicled by the media, Indian scientists are still grappling to nail the causes of this phenomenon.

With an aim to broaden the perspective on tsunamis, the Saha Institute of Nuclear Physics (SINP), Calcutta, roped in scientists from across the globe for a workshop from March 6-10. Several topics like the formation of tsunamis, potential areas of occurrences, its effects and the areas likely to be hit by tsunamis in the near future were discussed in the five-day meeting.

“Tsunamis are very different from typical surf swells,” said Professor Frederick Dias, who is from the Laboratoire de Mathematiques, Ecolenormale superieure de Cashan, France. He explained that it was not just the surface water that moves as waves during a tsunami. On the contrary, an entire water column from the surface right up to the ocean bed (often several kilometres deep) moves along with the waves. These waves contain immense amount of potential energy (energy by virtue of its position), which cause massive destruction on reaching shore due to the conversion of this potential energy to kinetic energy (energy by virtue of motion).

The next speaker, Professor Jean guy Caputo, of Laboratoire de Mathematiques, INSA de Rouen, France, explained the propagation of a tsunami and the formation of a storm surge or tidal-bore wave in a canal or a river where the depth or the width can vary. He also mentioned that the areas in India likely to be hit by tsunamis in the near future were the Andamans, the north-east coast of Gujarat and low lying coastal areas.

Asked about the possibility of a tsunami hitting India soon, Dr K.S.R. Murthy, deputy director of the National Institute of Oceanography, said, “Tsunamis cannot be predicted with certainty.” The Sumatra earthquake in December 2004, is believed to have occurred after accumulation of strain energy for over a few hundred years at the interface between Indian and Burmese plates. In Indian Ocean, we have only one subduction zone, the Andaman-Sunda trench axis. If this logic is followed, the possibilities for another tsunami to occur in the near future might appear less. However, such predictions may also be proved wrong.

The workshop ended on a positive note, with the scientists promising to conduct awareness programmes among coastal communities. This would help in reducing casualties in case another tsunami struck the country. Forestation with several types of coastal vegetation, depending on the environment suitable for their growth, could also be a significant remedy, they concluded.