Dimas Sianipar, Emi Ulfiana, Renhard Sipayung

Intense swarm seismicity took place before the 2017 Mount Agung eruption in Bali (Indonesia). However, the earthquake sequences were not well documented. In addition, there was a substantial delay between the peak of the seismic activity (late September) and the onset of the impending eruption (late November). We applied waveform-based hypocenter relocation and matched filter technique (MFT) to enhance the earthquake catalog of the swarm associated with the eruption. We detect fourteen times more events (5,803) than the routine catalog (407) from 1 August 2017 to 1 December 2017. The intense swarm initiated on 20 September 2017 at ~09:00 UTC, and the peak of the swarm occurred during 22-24 September with 1,473 events. The updated spatiotemporal evolution of the swarm seismicity shed light on the processes involved in a volcano reawaking and highlighted the use of MFT in volcano monitoring with existing regional seismic networks.