Community preferences for vertical evacuation in anticipation of megathrust-induced tsunami: Evidence from Pariaman, West Sumatra

Pariaman City, on Sumatra’s western coast, is highly exposed to tsunamis from potential Mentawai megathrust earthquakes, with a limited lead time of 20–30 minutes. This study examines community evacuation preferences—whether horizontal or vertical—and the factors that influence them. Using a quantitative descriptive approach, 399 respondents completed an online questionnaire. Data were analyzed descriptively and with binary logistic regression to assess demographic (age, gender, education), spatial (distance from the coast, travel time), and socio-cultural (disaster knowledge, community influence) determinants. Results show high overall awareness (92%) but gaps in technical knowledge of evacuation procedures and shelter locations. Evacuation preferences were split between horizontal (53.9%) and vertical (44.3%), with higher-educated and productive-age respondents favoring vertical options. Spatial factors also played a role: residents closer to the coast with longer travel times preferred vertical evacuation, whereas those farther inland or with faster access favored horizontal routes. Social influence, such as following others, strongly affected decisions, highlighting collective behavior in emergencies. The study underscores that tsunami evacuation decisions are multi-deterministic, shaped by demographic, spatial, infrastructural, and social factors. Policy implications include strategically located Vertical Evacuation Shelters, clear evacuation routes, and strengthened community-based risk communication.