Traces of ancient tsunamis that have not been documented in historical sources, or so-called palaeotsunamis, were searched for by scientists from AMU on the coast of Sumatra. Prof. Witold Szczuciński, Prof. Jędrzej Majewski and Dr Robert Jagodziński from the AMU Faculty of Geographical and Geological Sciences, together with Prof. Nazli Ismail and other employees of the Syiah Kuala University of Indonesia, carried out geological research there.
Thanks to these studies, it has become possible to determine how often and how large tsunamis hit a particular stretch of coastline, which allows cities and their inhabitants to be better prepared for future disasters. As Professor Jędrzej Majewski reminds us, the 2004 tsunami affecting the Indonesian province of Aceh was the biggest disaster of its kind in human history, claiming at least 230,000 lives. It devastated not only Aceh but also the coasts of Thailand, Sri Lanka, India and other countries around the Indian Ocean. - "At the time, there was no scientific evidence or awareness that such a massive tsunami could occur in Aceh. Scientific research conducted after 2004 confirmed that this tsunami was not an anomaly - at least ten devastating tsunamis have hit the area in the last 7,000 years," says Prof Jędrzej Majewski. The local population was unaware of these previous events, as they settled on this coast only after 1394, by which time a previous tsunami had destroyed low-lying settlements and driven out earlier inhabitants. This information comes from archaeological research, in which Prof Jędrzej Majewski was also involved.
However, as the scientists emphasise, some population groups have traditional knowledge of previous tsunamis. For example, on the island of Simeulue, south of Aceh, where the residents passed on knowledge about tsunamis and how to react, in the form of rhymes taught to children. As a result, only seven people out of a population of nearly 80,000 died there during the day of the disaster, showing that properly prepared individuals can survive even such huge catastrophes.
However, to achieve this level of preparedness, the inhabitants must know about previous disasters and know how to behave in the face of future ones. This is what the palaeotsunami research conducted by the AMU researchers is helping to do. While in North Sumatra, in the province of Aceh, post-2004 studies have already provided a wealth of information about tsunamis, other places on the west coast of Sumatra may be similarly at risk but insufficiently studied. - "Without accurate data and evidence of where else tsunamis may occur, many local administrations are delaying preparations or taking too little action. The reason is simple - the needs remain many, and it is not known if and how often tsunamis occur", explains Professor Jędrzej Majewski. In his opinion, there is an urgent need to search for and document traces of past tsunamis along the entire coast, and since this information is not found in historical chronicles, reference should be made to the ‘geological archives’, recorded in the sediments of coastal marshes, which hold traces from hundreds or even thousands of years ago.
The research is part of the project ‘Palaeotsunami sediments as a key to understanding the tectonic and tsunamigenic behaviour of the Sumatra subduction zone through time’, for which Prof Jędrzej Majewski received funding from the National Science Centre, under the Polonez Bis 3 competition.
Photo: Private archive of Prof. Jędrzej Majewski
