Java Hit by Two Megathrust Quakes Since 1994; UGM Expert Explains

TEMPO.CO, Jakarta - The threat of megathrust earthquakes in southern Java should not be seen as a source of terror. For disaster experts, the priority is to ensure that the public understands the risks and is adequately prepared when a disaster strikes.

Gayatri Indah Marliyani, a seismic expert from Gadjah Mada University’s (UGM) Geological Engineering Department, stated that a megathrust is not a purely hypothetical threat. In the last 32 years, this phenomenon has occurred twice in Java, triggering destructive tsunamis on both occasions.

"Megathrust has occurred twice in the last 32 years, in 1994 in southern Banyuwangi and in 2006 in Pangandaran. Both events were accompanied by destructive tsunamis," explained Gayatri during the seminar "20 Years of Yogyakarta Earthquake 2006 and Anticipation of Java Megathrust Earthquakes" at the UGM Central Building on Saturday, May 31, 2026.

According to Gayatri, an understanding of active faults and the megathrust zone in southern Java is the foundation for disaster mitigation. She reminded the public that science has not yet been able to accurately predict when an earthquake will strike.

Focus on Mitigation, Not Speculation

Therefore, she said, it is better for the public not to be trapped in speculating about the timing of the earthquake. What is more urgent is to reduce risks through earthquake-resistant housing construction, providing clear evacuation routes, and increasing disaster literacy.

"Rather than focusing on speculating when the earthquake will occur, the primary concern is how to mitigate the risk of the disaster," she added.

Gayatri also noted the fading collective memory of the population regarding major disasters, especially among the younger generation, who did not directly experience the 2006 Yogyakarta earthquake. This condition is considered to reduce awareness of existing geological threats to this day.

Data as a Reference for Preparedness

Dwikorita Karnawati, the head of the Meteorology, Climatology, and Geophysics Agency (BMKG) during the 2017–2025 period, stated that information about the potential of Java's megathrust is not intended to cause panic, but serves as a basis for developing measured mitigation scenarios.

Dwikorita explained that several areas, such as the Sunda Strait, southern Java, and Mentawai, are considered seismic gap zones, which means areas that have not experienced major earthquakes for a long time and are thus suspected to have accumulated tectonic energy for more than two centuries.

"This scientific data is absolutely necessary as a reference for emergency structural preparedness," said Dwikorita.

She reminded the public to approach earthquake threat information calmly and rationally. According to her, education about mitigation, evacuation drills, and the ability to discern accurate information are key to tackling disaster threats.

Dwikorita acknowledged that to date, there is no technology capable of accurately predicting earthquakes. However, various research efforts are still being carried out to develop disaster scenarios as a basis for drawing up mitigation steps.

"Without scenarios, we have no basis for mitigation. Therefore, research is still needed so that we can prepare for the worst-case scenarios," she explained.

Government and Academic Collaboration

Head of the Regional Disaster Management Agency (BPBD) Bantul, Mujahid Amrudin, stated that the government has been developing various mitigation strategies, from establishing UNESCO-standard Tsunami Ready Communities and providing evacuation points to installing early warning systems and family-level disaster education.

"These efforts will continue to be improved through collaboration with the academic community, so that the risk of casualties and losses due to disasters can be minimized as much as possible," he said.

Read: BMKG Records 136 Earthquakes in West Java Throughout May

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