A low-cost tool can help people plan successful evacuation routes during a tsunami

People living in coastal communities sometimes have only minutes to reach a safe spot after an earthquake-triggered tsunami. But will the evacuation route that they’ve chosen lead them to safety?

In a new study published in Seismological Research Letters, researchers Alejandra Gubler and Matías Carvajal demonstrate that the safety of these routes strongly depends on how soon after an earthquake people begin to evacuate.

The Pontificia Universidad Católica de Valparaíso and Pontificia Universidad Católica de Chile researchers built a low-cost tool that combines data from GPS tracks, collected from participants in community evacuation drills in Chile’s Viña del Mar, with models of inundation from the type of tsunami expected in this central region of the country.

In their analysis of 119 GPS trajectories collected from drill participants, they discovered that successful evacuation depends strongly on when people begin moving. If people began to evacuate immediately after the start of the earthquake, 100 of the 119 trajectories studied would have allowed people to reach safety before being inundated.

But if they waited eight minutes after the earthquake’s origin before evacuating—roughly when a tsunami warning would be issued—only 49 of the trajectories would have led to safety.

And if people were to evacuate twelve minutes after the earthquake origin, only three of the trajectories would reach higher ground before rising waters caught up to them.

“In near-field settings like central Chile, where the tsunami can reach the coast within minutes of the earthquake, that margin is very small, so every minute really counts,” said Gubler.

Gubler and Carvajal created simple but dramatic video animations of their findings, to help residents, authorities and decision-makers understand the critical consequences of delayed evacuation.

“What really surprised us was what happened when we showed the videos to the drill participants. As they watched their own trajectories being reached by the simulated tsunami, you could hear a general ‘oooohhh’ across the room,” said Gubler.

“That reaction showed us how much the videos captured their attention, in a way that a graph or a curve rarely does,” she added.

The researchers collected personal GPS data from participants, mostly university students, in tsunami evacuation drills conducted between 2022 and 2026. The participants were instructed to follow an evacuation route shown on the official evacuation map. Some of the recorded trajectories followed local evacuation signage, however, which does not always match the official map.

Gubler and Carvajal compared the trajectories with a simulated time-dependent tsunami inundation field for a plausible subduction earthquake scenario in the region.

“Most of the tools communities rely on, such as evacuation maps, are static. They show where to go, but not how much time you actually have to get there,” Gubler noted. “We wanted to put that time dimension front and center, and today it is much more feasible to do so, because we can combine GPS tracks recorded during real drills with time-dependent inundation modeling.”

The researchers also grouped the 119 trajectories into 13 main corridors, finding that the number of feasible corridors—paths that would lead to safety before being overtaken by the tsunami—decreased substantially as people delayed their evacuation.

There were also strong differences in some cases between neighboring corridors. In one corridor, 91% of participants would have completed their evacuation when leaving eight minutes after the earthquake origin.

In a corridor only 200 meters away, however, only 13% of participants would have safely evacuated under the same start time. The differences reflect both the local inundation pattern and the recorded movement of the people, the researchers said.

“We have actually gathered a lot of information on the difficulties participants encounter during the drills, such as problems with particular routes or infrastructure,” Gubler said. “Analyzing it properly is something we would like to do in future work.”

Gubler said the researchers also have plans to work with local authorities and the institutions that supported the study to share the animations more widely.

“That said, although we believe it is valuable to show these videos to the whole community, we think the awareness effect is much greater when people have recorded their own route during a drill and then see themselves being reached by the tsunami,” she said. “Watching someone else’s trajectory is informative; watching your own is what really makes an impression.”

The paper was published as part of an upcoming SRL Focus Section on Advances in Operational Response.