A Low-Cost Tool for Communicating the Time-Critical Feasibility of Near-Field Tsunami Evacuation: A Proof of Concept in Viña del Mar, Chile

Near-field tsunamis can leave coastal communities with only minutes to reach safe areas, so how quickly people begin moving after the earthquake shaking is critical to evacuation success. Static evacuation maps do not represent this time dependence, whereas more complex evacuation models can be data-intensive, costly, or difficult to scale. We introduce a simple, low-cost tool that combines Global Positioning System (GPS) tracks recorded with mobile applications during evacuation drills with tsunami inundation modeling. As a proof of concept, we apply the tool in Viña del Mar (central Chile), where a large tsunami is expected and evacuation is particularly challenging because of the long distances required to reach safe areas. We analyzed 119 GPS trajectories collected during drills between 2022 and 2026 and compared them with simulated inundation for a plausible subduction earthquake scenario. For illustration, each trajectory was evaluated under three departure times measured from the earthquake origin time: 0 min (T0), 8 min (T8), and 12 min (T12). T0 represents immediate evacuation, T8 departure when a warning is issued, and T12 departure when the tsunami is already reaching the coast. A trajectory was considered feasible if the participant completed the evacuation before being reached by the simulated inundation. Of the 119 trajectories, 100 were feasible under T0, 49 under T8, and only 3 under T12, showing how strongly evacuation success depends on when people begin moving. Most trajectories followed 13 main evacuation corridors. Feasibility varied sharply among corridors, even between neighboring routes within the same departure scenario. By overlaying the trajectories on the advancing inundation, the approach produces intuitive videos that make the consequences of delayed departure visible to residents, authorities, and decision-makers. Inexpensive and easily replicable, the method complements detailed evacuation modeling and may be particularly useful in tsunami-prone communities with limited resources, supporting evacuation awareness, preparedness, and risk communication.