Using fluorescent lights, Kerry Sieh and Charles Rubin of the Earth Observatory of Singapore look for charcoal and shells for radiocarbon dating. | Earth Observatory of Singapore

5,000-Year-Long Tsunami Record Found in Guano-Encrusted Sumatran Cave

The discovery of sediment layers in a seaside cave represents the longest record of tsunamis in the Indian Ocean, and the clearest record of tsunamis anywhere in the world.

July 19, 2017
1:25 PM EDT
W W hen the December 26, 2004 Indian Ocean earthquake occurred off the west coast of Sumatra, Indonesia, the 9.1 magnitude event — the third-largest tremor ever recorded on a seismograph — was so strong that it caused the entire planet to vibrate by as much as 0.4 inches. The quake triggered a series of devastating tsunamis that killed up to 280,000 people in fourteen countries, inundating some coastal communities with 100-foot-tall waves. The tsunamis are now regarded as being among the deadliest natural disasters in all of recorded history.
Archaeologist Patrick Daly (wearing hat), Kerry Sieh (pointing), Charles Rubin (second from left), Benjamin Horton, and Jedrzej Majewski (behind Daly) are seen in an Indonesian sea cave. | Earth Observatory of Singapore
The stratigraphy of the sea cave in Sumatra excavated by scientists from the Earth Observatory of Singapore, Rutgers, and other institutions shows lighter bands of sand deposited by tsunamis over a period of 5,000 years and darker bands of organic material, largely consisting of bat guano. | Earth Observatory of Singapore