This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: 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 had begun to evacuate immediately after the start of the earthquake, 100 of the 119 trajectories studied would have allowed them to reach safety before being inundated. But if they had 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 12 minutes after the earthquake's origin, only three of the trajectories would allow them to 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.
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