The western extension of the Balantak Fault revealed by the 2021 earthquake cascade in the central arm of Sulawesi, Indonesia

Two shallow earthquakes of moment magnitude 6.2 and 5.8 occurred in the central arm of Sulawesi on 26 July 2021 and 26 August 2021, respectively. The fault responsible for the earthquake had previously only been partially mapped, thus making further analysis of its characteristics crucial for the as...

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Published inGeoscience letters Vol. 11; no. 1; pp. 35 - 10
Main Authors Simanjuntak, Andrean V. H., Palgunadi, Kadek H., Supendi, Pepen, Muksin, Umar, Gunawan, Endra, Widiyantoro, Sri, Rawlinson, Nicholas, Daryono, Mudrik R., Daryono, D., Karnawati, Dwikorita, Hanifa, Nuraini R., Pratama, Cecep, Ida, Rachmah
Format Journal Article
LanguageEnglish
Published Cham Springer International Publishing 01.12.2024
Springer Nature B.V
SpringerOpen
Subjects
Atmospheric Sciences
Biogeosciences
Cluster analysis
Earth and Environmental Science
Earth Sciences
Earthquake
Earthquakes
Fault
Focal mechanism
Geological hazards
Geophysics/Geodesy
Oceanography
Planetology
Research Letter
Rupture
Seismic activity
Seismic hazard
Seismicity
Static stress change
Waveforms
Sulawesi
Indonesia
Static stress change
Fault
Earthquake
Focal mechanism
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Summary:Two shallow earthquakes of moment magnitude 6.2 and 5.8 occurred in the central arm of Sulawesi on 26 July 2021 and 26 August 2021, respectively. The fault responsible for the earthquake had previously only been partially mapped, thus making further analysis of its characteristics crucial for the assessment of seismic hazard. In this study, we exploit data from a regional seismic network, relocate the associated seismicity using the double difference method with an updated velocity model, determine focal mechanisms from full-waveform inversion, and analyze the static stress changes caused by the mainshock. Our relocated hypocenters and focal mechanism solutions reveal two earthquake clusters, one at the Central Balantak Fault that exhibits normal slip on a SE–NW trending rupture, and the other at the West Balantak Fault, which exhibits dextral strike-slip motion on a SE–NW trending rupture. The additional static stress increase transferred by the Mw 6.2 mainshock may have triggered the subsequent Mw 5.8 event. A detailed assessment of previously unmapped faults in Central Sulawesi is essential for a more comprehensive understanding of seismic hazard in the region.
ISSN:2196-4092
DOI:10.1186/s40562-024-00353-7