Survival Guide: Signs of a Tsunami, a National Geographic Expert Weighs In

Photograph of Beverly Goodman by Howie Goodman

Editor's Note: In light of the devastating earthquake and tsunami in Japan and possible future events along the Pacific Coasts, we're sharing some recently published tips from Adventure on how to survive a tsunami. Read more tips in our Survival Guide.

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How to Survive a Tsunami
By Damon Tabor, originally published in the August/September 2009 editon of Adventure

“One of the troubles with tsunamis is that they aren’t regular enough,” says geoarchaeologist and National Geographic Emerging Explorer Beverly Goodman. “You don’t want to scare everyone, but it’s not fantasy, either. Anytime you’ve got a combination of water and tectonics, there’s a potential. It has happened and will happen again.”

If you live near the coast, use Google Earth to determine your home’s sea level height and distance from shore. Map out an evacuation route if you live in a danger zone—generally less than 25 feet above sea level and within a mile of shore. Sign up to receive early alert text messages from the National Oceanic and Atmospheric Administration’s tsunami warning center. Some waves, however, could reach coastal areas faster than the system can react. Keep a grab-and-run kit in a waterproof river guide’s pack, which could help you float.

If you see ocean water dramatically recede, immediately run for high ground (go by foot, since the earthquake that launched the wave could make roads impassable). Head for the nearest tall concrete building, ideally at least ten stories high. If you’re overtaken by waves, swim hard and keep your legs up. Submerged trees, telephone poles, and roofs can drag you underwater. “I just treated it like whitewater kayaking,” says Paul Landgraver, a Thailand-based scuba diving instructor who was carried more than a half mile in four minutes by the surge during the 2004 tsunami in Asia. “I looked for smooth water, avoiding obstacles by swimming left or right as best I could. I tried to float as much as I could on the surface.” As soon as you can, get out of the water. When tsunamis waves recede, they can pull objects miles out to sea.

The Expert: Beverly Goodman, Ph.D. ||| Geoarchaeologist, NG Emerging Explorer

The project: You’d expect 100-foot-tall waves to leave behind a clear path of destruction. You’d be wrong. To identify past events—and predict future ones—Goodman collects the smallest of clues: grains of sand.

“Traditionally, scientists searching for evidence of a past tsunami look for marine deposits on land. But after the chaos of a giant wave, people return home fairly quickly. They rebuild. They clean up. Evidence of the event is erased. So instead of looking on shore, we go underwater. Using an aluminum irrigation pipe connected to a pneumatic hammer, we take core samples from the seafloor. We then identify unusually large layers of deposits—indicating a single, violent event—and analyze the sand grain size to estimate wave height, the magnitude of the event, and when it happened. We feed that information into tsunami databases. Models are only as strong as the data you put into them. The more we know about past tsunamis, the better we can predict coastline risk.”