Indigenous knowledge-based tsunami disaster mitigation strategies in South Lampung coastal areas, Indonesia

South Lampung Regency, located in southern Sumatra, Indonesia, records a high disaster risk index score of 176.14, with its coastal areas acutely exposed to tsunami hazards. Historical evidence of the 1883 Krakatoa and the 2018 Anak Krakatau tsunamis, which caused 118 deaths and extensive infrastructural losses, underscores the urgency of comprehensive mitigation efforts. This study adopts a qualitative ethnographic design integrated with geographic information system (GIS)-based spatial analysis to examine how coastal communities in Kalianda and Rajabasa transform indigenous knowledge into practical resilience strategies. Data were gathered through in-depth interviews, participant observation and satellite image–based land-use mapping. The spatial analysis classified six vulnerability zones and revealed that 42% of settlements remain within high-risk coastal buffers. The findings indicate that local communities complement structural mitigation, such as breakwaters and evacuation sites with culturally embedded practices, including interpreting natural warning signs, reinforcing communal solidarity and intergenerational transfer of evacuation knowledge. Contribution: The research contributes an integrated vulnerability map that merges structural, environmental and socio-cultural dimensions, demonstrating that the fusion of indigenous knowledge and scientific spatial assessment substantially enhances tsunami preparedness. These insights provide a replicable model for policymakers and disaster risk-reduction practitioners in similar coastal regions.