“The Atlantic” Interviews Wellesley Geosciences Professor about New Findings from the Site of the 2004 Southeast Asia Earthquake and Tsunami

A village near the coast of Sumatra lays in ruin after the Tsunami that struck South East Asia (Jan. 2, 2005)
Photo provided by U.S. Navy photo / Philip A. McDaniel
August 1, 2017

Katrin Monecke, assistant professor of geosciences at Wellesley, was interviewed for an article in The Atlantic on a scientific excursion to Southeast Asia, site of the earthquake that generated the Indian Ocean tsunami of December 26, 2004. By the end of that fateful day, more than 150,000 people were dead or missing, and millions more were homeless in 11 countries, making it perhaps the most destructive tsunami in history.

Dozens of scientists went to Southeast Asia a few months after that tsunami, asking questions: Had this happened before? Could it happen again?

They thought the answers might be found in sand. Tsunamis pick up sand from the depths of the ocean floor and deposit it on land as the waters recedes.

Author Sarah Zhang wrote, “Low-lying coastal plains are good places to look, as well as lagoons or mangrove swamps that trap sand. Several sites around the Indian Ocean have allowed scientists to begin piecing together a fragmentary history of Indian Ocean tsunamis…And to that, they’ve now added an exciting new find: a coastal cave in Indonesia containing layers of sand left by tsunamis all the way back to the Stone Age, 7,400 years ago.”

Zhang spoke with Monecke, who wasn’t involved in that research but has worked on other tsunami deposits in Southeast Asia, about the discovery of the cave, which gives scientists a new location to search for evidence of past tsunamis. Monecke said, “It is really a spectacular site.”

Another key to answering scientists’ questions, in addition to the sand, turned out to be bats. Tsunamis had been inundating this cave for thousands of years, during which time bats were also pooping on the cave floor. Over time, layers of sand developed that were separated by dark bands of bat poop. One of the scientists called the discovery a “holy grail moment.”

Within the span of a single century, around 1300 BCE, the bands show there were four tsunamis.

Monecke told Daily Shot writers, scientists can’t predict earthquakes or tsunamis; they can only estimate the probability of future events by looking in the historic or geologic record. “By understanding the recurrence intervals of past tsunamis, we can assess the hazard of a region, and that allows local coastal communities to prepare as much as possible for future disasters,” she said.