Tsunami was predictable following powerful earthquake under the sea
The fact that a powerful earthquake in Indonesia would give rise to a devastating tsunami was predictable. Just a few months ago, some students in the Physics Faculty at Athens University presented a project citing Indonesia as a classic example of the phenomenon. Specialists say that thousands of lives could have been saved if local authorities had warned residents and visitors of the likelihood of such dangers. When the sea receded dramatically, they would have known they had to leave the beach at once. The students, Christina Zenteli and Ioannis Degleris, presented their paper last May as part of their coursework. «As my students noted in their paper, that area has been struck by tsunamis in the past, causing thousands of casualties,» Assistant Professor Elissavet Dologlou told Kathimerini. «That is because of the mechanism that generates earthquakes in the area: One of the two plates at a fault line sinks and the other rises; the ocean moves suddenly, creating waves that carry huge masses of water.» Given that scientists know the tectonic features of the area, the question arises as to why residents and visitors are not informed of how to act in such cases. «An ordinary student who knows about tectonic plates would know what to expect,» says Dologlou. «I believe what happened was the consequence of a tragic omission. I think the authorities did not make the appropriate announcements for fear they would harm their economy. But wouldn’t it be better for people going to the area to know there was a problem?» The tragedy in South Asia has focused attention once again on scientific knowledge. «The first issue is the dissemination of knowledge to the public,» notes Dologlou. «In areas such as Halkida that have tidal phenomena, local residents are familiar with them. But when water recedes in an area where it is not usual, it means the mass of water has been moved by some cause. The simplest thing to do in such a case is to get away from the shore. Thousands of people would have been saved if they had gone 500 meters inland in time.» On the other hand, the extent of the disaster in South Asia does not mean that all coastal areas in the world are at similar risk. «Greece is not much affected by tsunamis,» explains Dologlou. «Similar seismic mechanisms operate only in the Hellenic Arc, the point at which the Earth’s lithospheric plates meet. «But earthquakes in this region emit far less energy, so the tsunami is lower and the volume of water shifted is smaller. Besides, the distances between shores are very small. That means that wherever a tsunami develops in Greek waters, it will hit the nearest shore in five-10 minutes, so there is no time to react. «So I’ll take the risk of saying that a tsunami warning system in Greece would be useful purely for research purposes. Only a system based in the southeastern Mediterranean might be of practical use in extreme circumstances, such as a very powerful earthquake in Sicily.»
