The cave retains the deposits washed ashore by huge waves over thousands of years
A cave on the northwestern coast of Sumatra holds a remarkable record of big tsunamis in the Indian Ocean.
The limestone opening, close to Banda Aceh, retains the sandy deposits washed ashore by huge, earthquake-induced waves over thousands of years.
Scientists are using the site to help determine the frequency of catastrophes like the event of 26 December 2004.
This is being done by dating the cave's tsunami-borne sediments, which are easy to see between layers of bat droppings.
"The tsunami sands just jump right out at you because they're separated by guano layers. There's no confusing the stratigraphy (layering)," explains Dr Jessica Pilarczyk.
"It makes for interesting field work; I'm not going to lie to you. The bats get very excited when people are disrupting their space. But from a geologist's point of view, this cave has the most amazing stratigraphy," she told BBC News.
Dr Pilarczyk was speaking here in San Francisco at the American Geophysical Union (AGU) Fall Meeting, the world's largest annual gathering of Earth scientists.
She is part of a team of researchers - led by Prof Charles Rubin - from the Earth Observatory of Singapore, an institute of Nanyang Technological University that is investigating the coastal history of Indonesia's largest island.
The tsunami record from about 7,500 to 3,000 years ago is impeccable, say the scientists
Sumatra's proximity to the Indo-Australia and Sunda tectonic plate boundary, and the giant earthquakes that occur there, means its shores are at risk of major inundations.
Understanding how often these occur is important for policy and planning in the region.Continued
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