Towering walls of water traveling at the speed of a jetliner, with coastal communities from Japan and Hawaii to South America and the U.S. West Coast in their path.
That was the frightening possibility seismologists and others feared when an 8.8-magnitude earthquake—one of the most powerful tremors ever recorded—struck off Russia’s eastern coast on July 29, triggering a Pacific-wide tsunami.
Warnings and evacuation orders were issued across the Pacific. But compared to past devastating tsunamis—such as the Indian Ocean tsunami of 2004, which killed more than 200,000 people across 15 countries—the waves and resulting damage proved moderate. The only reported death: a 58-year-old woman who died when the car she was driving plunged down a cliff as she attempted to evacuate in central Japan.
“The world was lucky,” said geologist Gregor Eberli, the Robert N. Ginsburg Endowed Chair in Marine Geosciences at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science.
Eberli, who has studied the Earth’s sediments as recorders of environmental changes for most of his scientific career, said that while the earthquake that struck off Russia’s Kamchatka Peninsula was the sixth largest ever recorded, large-scale vertical displacement of the seafloor did not occur.
“It is the vertical displacement of the seafloor that is mostly responsible for the height of the tsunami wave,” he explained. “But even a flat tsunami can be dangerous because local coast topography can build up the wave. Luckily, this tsunami was announced early enough that coastal communities could evacuate."
Last week’s temblor was not the first to strike the region, which is located within the Pacific Ring of Fire, so called because of the high number of earthquakes and volcanoes that occur there. A 9.0-magnitude quake hit the peninsula in 1952, spawning a tsunami that devastated the coasts of Kamchatka and the Kuril Islands, according to the National Oceanic and Atmospheric Administration (NOAA).
The Indian Ocean tsunami of Dec. 26, 2004, is widely considered the deadliest, with estimates placing the death toll at approximately 230,000. But long before that, tsunamis wrought havoc in coastal areas. As many as 50,000 people perished after an 8.5-magnitude earthquake struck off the coast of Lisbon, Portugal, on Nov. 1, 1755, producing a tsunami with waves that crested up to 59 feet. NOAA’s Global Historical Tsunami Database includes information on tsunami events from 2000 B.C. to the present.
It is in the sediment that scientists can document and learn about tsunamis that occurred centuries ago.
“They leave a signature,” said Sam Purkis, professor and chair of the Rosenstiel School’s Department of Marine Geosciences. “As the wave smashes into the coastline, it moves huge quantities of rocks and sediment and trees and detritus. And that forms a layer that preserves the past.”
Geologists drill cores or dig trenches in areas where they suspect a tsunami has occurred, then use carbon dating to determine the age of the material, creating a historical record of tsunamis when human memory of those events no longer exists, Purkis explained.
Such research is critically important, as it gives geologists a way to predict tsunamis of the future.
“Tsunamis are the geologic record of earthquakes—especially the mega earthquakes and the tsunamis that cause destruction across ocean basins,” Eberli said. “These mega earthquakes in subduction zones, where one tectonic plate slides under an overriding plate, occur because, as the plates move together, stress is built up that is released, momentarily causing the rupture and displacement. The general theory is that the rate of convergence is mostly responsible for the frequency of the earthquakes, or stress release, at a given subduction zone. And by studying the recurrence rate of past tsunamis, future occurrences can be estimated.”
Both Eberli and Purkis have conducted extensive tsunami-related research.
Eberli has studied everything from the sedimentology record of tsunamis in the Indian Ocean to the likelihood of a tsunami hitting South Florida. In a 2014 study, Eberli’s marine geosciences colleague, Falk Amelung, and doctoral student Kelly Jackson traveled to Sri Lanka to take cores from coastal lagoons to search for earlier tsunami deposits. “One lagoon proved to have an excellent record of older tsunami deposits and allowed us to establish the recurrence rate in the last 6,645 years,” Eberli said.
One might say Eberli was destined to study tsunamis. He grew up close to Lucerne, Switzerland, learning about the 1601 earthquake that triggered a tsunami that engulfed the city. Later, during studies at the Swiss Federal Institute of Technology, he learned about the mechanics and causes of tsunamis. “Lately, I have focused my studies on the large current deposits in the world’s oceans,” he said, “but I have not forgotten tsunamis.”
Meanwhile, in a 2023 study, Purkis and a team of scientists studied the 2022 eruption of a submarine volcano in Tonga that was more powerful than the largest U.S. nuclear explosion. In their study, they used a combination of before-and-after satellite imagery, drone mapping, and field observations to create a tsunami simulation of the Tongan Archipelago, discovering that the underwater terrain of the region helped trap tsunami waves and ultimately spared the inhabited islands of Tonga from much more serious damage.
With the Earth constantly changing due to geologic forcing, more earthquakes and the tsunamis they generate will surely happen in the future. But just how effective are the detection, forecasting, and warning systems that are in place around the world?
“After the 2004 Indian Ocean tsunami, the scientific community advocated for a warning system based on buoys in the ocean that detect vertical displacement caused by a tsunami wave, and that system is in place now,” Eberli said. That warning system, he added, “worked perfectly and gave coastal areas several hours to evacuate.”
NOAA’s two tsunami warning centers operate around the clock, seven days a week, with the mission of protecting life and property. Staff monitor for tsunamis and the earthquakes that may cause them, forecast tsunami impacts, and issue tsunami messages.
