When a volcano in or under the ocean violently erupts, the massive upheaval of earth, followed by its rapid descent, can, occasionally, produce a second major disaster: a tsunami. This rare double event has only occurred once in recent history – to devastating effect. Now, a team of researchers from the University of Rhode Island have leveraged the supercomputing power of the San Diego Supercomputer Center (SDSC) to model that volcanic tsunami, with the hopes of saving lives in the future.

When the Anak Krakatoa volcano off the shores of Indonesia (itself the “child” of the infamous Krakatoa volcano) erupted in December 2018, a massive tsunami ensued, making landfall on the Indonesian coast, injuring over 14,000 people and killing over 400. However, the tragedy also afforded researchers an opportunity: a similar event hadn’t occurred for over a century, so for the first time, they were able to test their models against reality at a granular level.

The project – a collaboration between URI and the British Geological Survey – simulated several different possible versions of the 2018 eruption and tsunami, comparing the results to post-tsunami surveys of the landscape. The researchers were able to reproduce the tsunami through their simulations, adjusting the volume of the collapse and the landslide range such that the landscape matched tide gauge records and survey results. However, they also cautioned that the relative lack of warning signs makes it difficult to effectively prepare for such an event.

To run the simulations, the research team used SDSC’s Comet supercomputer, a system comprised of 1,944 Intel Haswell-based compute nodes and 72 Nvidia-based GPU nodes that delivers 2.76 peak petaflops.

“It saved us a lot of time being able to model all of those scenarios concurrently on a supercomputer,” said Lauren Schambach, a doctoral student at URI, in an interview with SDSC. “As our understanding of the complex physics related to tsunamis grows, access to supercomputers such as Comet allows us to improve our models to reflect that, whereas if we did not have access, the amount of time it would take to such run simulations would be prohibitive.”

While the results of the study didn’t lay out an easy course for protecting against volcanic tsunamis, the researchers see their work as a foundation for substantial improvements to tsunami preparedness in the future.

“We are hopeful that our continued research reduces warning systems from several hours to approximately ten minutes,” said Stephan Grilli, chair of the Department of Ocean Engineering at URI, “so that more people can reach safety prior to a tsunami.”

About the research

The research discussed in this article was published as “Modelling of the tsunami from the December 22, 2018 lateral collapse of Anak Krakatau volcano in the Sunda Straits, Indonesia” in Scientific Reports. The paper was written by Stephan T. Grilli, David R. Tappin, Steven Carey, Sebastian F. L. Watt, Steve N. Ward, Annette R. Grilli, Samantha L. Engwell, Cheng Zhang, James T. Kirby, Lauren Schambach and Muslim Muin and can be accessed here.

To read the SDSC article discussing this research, click here.