Disaster waiting to happen?: Mount Merapi erupts hot lava as seen from Sleman, in Yogykarta province of Indonesia, 21 May 2006.

Credit: AFP

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SYDNEY: A new analysis of the likelihood of volcanoes and earthquakes to cause future "mega-disasters" in the Asia-Pacific region says these events may affect many more people than previous estimates suggest.

Vast cities such as Manila in the Philippines – with 18 million residents – are particularly at risk, according to the analysis, completed by government agency Geoscience Australia.

The report is to be revealed today at the Australian Earth Sciences Convention 2008 in Perth.

Focus on people, not records

The research looked at the impact of earthquakes and volcanoes on densely populated cities in the hazard-prone Asia–Pacific region. Disaster research in the region has increased since the Asian tsunami in 2004, which was triggered by a magnitude 9 earthquake and killed more than 225,000 people.

Most earthquake and volcano risk analysis is based on historical records which go back only a few hundred years. Extreme geological events on the other hand may strike every few thousand, or even hundred thousand years. Risk estimates based on historical records also don't account for recent demographic changes, the researchers say.

Populations are continuing to rise in the Asia–Pacific with most people packed into densely populated cities. This new analysis pinpoints areas most likely to be at risk and evaluates the potential disaster impact.

"There has been a vast increase in the number of people and their vulnerability [to natural disaster] has tended to increase, with increasing population concentration in cities and mega deltas, which are subject to flooding and cyclone hazard," said Phil Cummins seismologist and co-author of the report. Cummins is project leader of the Earthquake Hazard and Neotectonics group of Geoscience Australia.

"As far as I am aware, until now there has been no analysis of the impact of such events [geological disasters] on present day or future populations," he said.