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Volcanic tsunami: a review of source mechanisms, past events and hazards in Southeast Asia

06 Jan 2014

A recent study led by Raphael Paris from Blaise Pascal University (CNRS-LMV) and Adam Switzer from the Earth Observatory of Singapore has highlighted the historical instances of a unique set of tsunamis. The study investigated the historical records of tsunamis generated not by earthquakes, which are the most common, but by volcanoes.

"There are hundreds of volcanoes in coastal settings in Asia and many more lie unmapped and even unnamed underwater. We just don’t know enough about volcanic tsunami hazard to make meaningful risk assessments on what are commonly very rapidly developing coasts" reminds Switzer, who was awarded a National Research Foundation Fellowship in 2010 in Singapore to study coastal hazards in the region.

The report considered all tsunamis generated by eruptive processes, rapid ground deformation and slope instability at volcanoes. At least 17 different volcanoes in Southeast Asia generated tsunamis in the last 400 years, with 40 events that have been reported since 1550. Some of the volcanic tsunami events killed thousands on Asian coasts. Two notable events emphasize this: the explosive volcanic activity of Krakatau (Indonesia) in 1883, and the lesser known but equally violent Ritter Island (Papua-New Guinea) eruption and tsunami of 1888, which had death tolls higher than 35,000 and between 500-3000, respectively.

The study highlights several key regions of concern in Indonesia, Papua New Guinea and the Philippines where, based on historical records, volcanic tsunamis may occur in the future. The study also notes that neighbouring countries such as Australia and China may be affected by far-field effects of tsunamis generated from volcanoes located in Indonesia, Papua New Guinea or the Philippines.

"Like all tsunamis," says Switzer, "the ones generated by volcanoes can travel long distances in the ocean and affect coastal populations thousands of kilometers away. A notable example is the 1883 tsunami generated by the eruption of the Krakatau, a volcano located between Java and Sumatra, which killed one person in Sri Lanka more than 3000km to the West.”

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Additional comments can be obtained from Adam Switzer aswitzer@ntu.edu.sg or Raphael Paris raparis@univ-bpclermont.fr

The study can be found here.