Analysis of swarm earthquakes around Mt. Agung Bali, Indonesia prior to November 2017 eruption using regional BMKG network

Geoscience Letters

Mohamad Taufik Gunawan¹  Ridwan Kusnandar¹  Pepen Supendi²  David P. Sahara³  Nanang T. Puspito³  Andri Dian Nugraha³ 

[1] Agency for Meteorology, Climatology, and Geophysics (BMKG), Jakarta 10610, Indonesia;Agency for Meteorology, Climatology, and Geophysics (BMKG), Jakarta 10610, Indonesia;Center for Earthquake Science and Technology (CEST), Research Center for Disaster Mitigation, Institut Teknologi Bandung, 40132, Bandung, Indonesia;Center for Earthquake Science and Technology (CEST), Research Center for Disaster Mitigation, Institut Teknologi Bandung, 40132, Bandung, Indonesia;Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, 40132, Bandung, Indonesia;

关键词: Mt. Agung;    Bali;    Seismicity;    BMKG regional seismic stations;    Double-difference relocation;    Focal mechanism;   

DOI  :  10.1186/s40562-020-00163-7

来源: Springer

【 摘 要 】

Mt. Agung, located in Karangasem-Bali, Indonesia, had a significant increase of swarm earthquakes from September 2017 until the recent eruption in November 2017. To analyze the seismic swarm and its correlation with the magmatic movement, we worked on the regional seismic data recorded by Agency for Meteorology, Climatology and Geophysics of Indonesia (BMKG) between September 14 to October 20, 2017. P-and S-wave phases of the swarm events had been manually picked. In total, 804 events in the time period of September 14 to October 20, 2017 were successfully determined. To improve the location precision, the double-difference relocation method was performed. We identified most of the events as Volcano-Tectonic type A (VT-A) earthquakes and located between Mt. Batur and Mt. Agung. Those events form a cluster striking in NE-SW direction at a depth between 2 and 20 km. Focal mechanism solutions for selected events below Mt. Agung show a thrust and strike-slip faulting regime. Interestingly, a trend of event propagation toward the summit of Mt. Agung was observed. The frequency of VT-A event occurrences is significantly increased at the later stage of the swarms. We concluded that the increased seismic activity in Mt. Agung was due to the migration of magma from the deep chamber to the shallow reservoir.

【 授权许可】

CC BY