Identification of Major Seismic Threats
The biggest earthquake threat to Indonesia is the Sunda Megathrust (Sumatran Megathrust) zone west of Sumatra, where the Indo-Australian plate subducts beneath the Eurasian plate at a rapid rate. This zone has produced major earthquakes in history including the 2004 Aceh earthquake with magnitude 9.1. Seismologists warn that this zone still holds enough energy to produce earthquakes with magnitude 8.0-9.0 in the coming decades.
The second threat is the subduction zone south of Java, which periodically produces large earthquakes with magnitudes 7.5-8.5. This zone affects millions of residents in major cities such as Jakarta, Bandung, and Yogyakarta. This risk is compounded by high population density and infrastructure concentrated in urban areas.
The third threat is other active faults throughout Indonesia such as the Palu fault in Sulawesi, which has produced large earthquakes such as the 2018 Palu earthquake with magnitude 7.5. The combination of these threats makes Indonesia face the highest seismic risk in the world and requires sustained investment in early warning systems, disaster-resistant infrastructure, and public education.