Tectonic Processes and Geohazard Assessment in the Sunda Arc

The Sunda Arc represents one of the world’s most active convergent margins, formed by the subduction of the Indo-Australian Plate beneath the Eurasian Plate. This complex system comprises a forearc trench, a chain of active volcanoes, and a series of back-arc thrusts, all of which interact to generate frequent earthquakes, volcanic eruptions and tsunamis. Variations in slab dip, sediment input and overriding plate structure govern the coupling behaviour along the megathrust, giving rise to heterogeneous seismicity and the formation of seismic gaps. Simultaneously, inland fault networks accommodate strain transfer and produce secondary seismic clusters. Advances in geodetic, seismic and InSAR monitoring now permit detailed mapping of interseismic locking, co-seismic slip and post-seismic relaxation. Integrating these observations with tsunami modelling and volcanic unrest monitoring is essential for robust geohazard assessment. Given the high population density along southern Sumatra, Java and Bali, improved understanding of tectonic processes underpins early-warning systems and informs land-use planning, disaster preparedness and resilience on a regional and global scale.

Research from Nature Portfolio

Detailed hypocentre relocation and waveform analysis of the shallow Mw 5.6 Cianjur earthquake sequence in West Java have revealed two orthogonal clusters of aftershocks at depths of 3–13 km, suggesting conjugate faulting within the upper crust. Rapid deployment of temporary seismic stations and use of double-difference relocation have sharpened the geometry of both NNW–SSE and WSW–ENE fault segments, improving our understanding of local rupture processes and guiding fault-based hazard models.

Broad-scale inversions of seismicity and GPS data have delineated pronounced seismic gaps south of Java, pinpointing potential sites for future megathrust events. Tsunami simulations based on worst-case rupture scenarios indicate maximum wave heights of 20 m on the south coast of West Java and up to 12 m in the east. These findings underscore the urgent need to reinforce early-warning infrastructure and community preparedness across densely populated coastal zones.

Tectonic Processes and Geohazard Assessment in the Sunda Arc publication trend

The graph below shows the total number of articles in tectonic processes and geohazard assessment in the sunda arc across all publications each year (not limited to Nature Index journals).

Technical terms

Subduction zone: The interface where one tectonic plate is forced beneath another, generating earthquakes and volcanism.

Megathrust: A large, dip-slip fault along a subduction interface capable of producing great earthquakes.

Interseismic coupling: The fraction of plate convergence that is stored elastically on a fault during the interval between major earthquakes.

InSAR (Interferometric Synthetic Aperture Radar): A remote-sensing technique that measures ground deformation by comparing phase differences in radar images.

Double-difference relocation: A seismological method that refines earthquake locations by minimizing differences in travel-time residuals between event pairs.

Coulomb stress: A metric of stress change on faults, indicating areas where failure is promoted or inhibited following an earthquake.

Seismic gap: A segment of a fault or megathrust that has not ruptured in a significant earthquake for an unusually long time, implying potential seismic hazard.

References

1. Seismic source analysis of the destructive earthquake November 21, 2022, Mw 5.6 Cianjur (Indonesia) from relocated aftershock. Scientific Reports (2024).
2. Implications for megathrust earthquakes and tsunamis from seismic gaps south of Java Indonesia. Scientific Reports (2020).
3. Co-seismic and post-seismic deformation associated with the 2018 Lombok, Indonesia, earthquake sequence, inferred from InSAR and seismic data analysis. Remote Sensing of Environment (2024).
4. Interseismic Coupling Along the Java‐Timor Subduction‐Collision Zone at East Indonesia. Geophysical Research Letters (2025).
5. Double-difference earthquake relocation using waveform cross-correlation in Central and East Java, Indonesia. Geoscience Letters (2023).