Indonesia Surrounded by 14 Megathrust Earthquake Zones, Japanese Expert Identifies Key Monitoring Points
Jakarta — According to the 2024 Indonesian Earthquake Source and Hazard Map, Indonesia is surrounded by 14 megathrust zones. This situation was highlighted by Japanese expert Professor Kosuke Heki from Hokkaido University.
He explained that there are similarities in the characteristics between Indonesia and the Nankai Trough, one of the world’s most active megathrust regions.
“We understand that earthquakes with magnitude 8 in Japan occur at intervals of approximately 50 to 100 years. This was our classical understanding before the occurrence of large earthquakes,” said Heki whilst serving as a Visiting Researcher at the National Research and Innovation Agency (BRIN) in late December 2025.
To date, the timing of major earthquakes remains difficult to predict. However, Heki added that long-term monitoring of Earth’s crustal deformation is a crucial key to disaster mitigation.
He also emphasised the role of the Global Navigation Satellite System (GNSS) and seafloor geodetic measurements in reading the accumulation of stress in subduction zones.
“We observe seismic coupling that locks almost along the entire length of the trench axis. Even at the very shallow plate boundary section, strain continues to accumulate for subsequent earthquakes,” he explained.
Additionally, Heki highlighted the phenomenon of slow slip events or gradual slippage that often occurs before major earthquakes. This phenomenon is said to be an early indicator of disaster.
According to him, Indonesia has significant potential to develop a similar monitoring system. This is because the country has many active subduction zones, from Sumatra, Java, Bali, Lombok to Maluku.
Indonesia is also considered capable of reading tectonic stress accumulation more precisely by strengthening its GNSS network.
“I am currently working on this issue in Indonesia,” said Heki.
In the latest map, one example is the Aceh-Andaman megathrust zone. That region has the largest earthquake potential with a maximum magnitude reaching 9.2.
There is also the Java megathrust, which has earthquake potential up to magnitude 8.9.
Previously, the Meteorology, Climatology and Geophysics Agency (BMKG) highlighted two megathrust zones that are in seismic gap conditions, namely the Sunda Strait and Mentawai-Siberut.
For hundreds of years, both regions have not released large amounts of energy. The Sunda Strait has been recorded since 1757, whilst Mentawai-Siberut since 1797.
BMKG stated that the term “waiting time” is not related to predicting when an earthquake will occur. However, the agency said there is accumulation of stored energy.
“What is meant is the accumulation of energy that is still stored because it has been a long time since a major earthquake has occurred. This does not mean an earthquake will happen in the near future,” BMKG stated in its official statement.