Similarities in the rupture process and cascading asperities between neighboring fault patches and seismic implications: The 2002–2009 Sumbawa (Indonesia) earthquakes with moment magnitudes of 6.2–6.6

A previously unidentified fault revealed by the February 25, 2022 (Mw 6.1) Pasaman Earthquake, West Sumatra, Indonesia

“…We selected seismograms with high signal-to-noise ratios (SNR) and that provided good azimuthal coverage, which resulted in 41 P-wave seismograms, 36 SH-waves seismograms, 37 Rayleigh-wave seismograms, and 22 Love-wave seismograms. We band-pass filtered the seismograms in the frequency range 0.01 to 1 Hz for body waves, and 0.004 to 0.006 Hz for the surface waves (Sianipar et al, 2022b). In our inversion, teleseismic SH-wave seismograms receive half the weight of teleseismic P-waves because SH-waves often have a lower signal-to-noise ratio and greater arrival time pick uncertainties.…”

“…6). We use a 15% peak slip (Ye et al, 2016;Sianipar et al, 2022aSianipar et al, , 2022b as the threshold to determine the asperity rupture area. This asperity (high slip region) is located northwest of the initial break, in the northern region of Mt.…”

“…The rupture extent obtained from finite-fault modelling is consistent with the aftershock distribution. Assuming that the total seismic moment depletion in this zone occurred with a circular rupture propagation, the estimate of static stress drop (Kanamori and Anderson, 1975;Supendi et al, 2021;Sianipar et al, 2022b) over the asperity is about 1.9 MPa. This low static stress drop may be related to the abundance of the aftershock productivity.…”

“…The rupture extent, foreshock, and aftershock distribution may reflect the structural control on this secondary fault segment (Salman et al, 2020). The mainshock asperity breaks the 14 km-long rupture around the hypocenter, while the aftershocks stopped expanding beyond about ~10 km to southeast and <10 km to northwest; this might suggest segmented or limited geological structure or an immature young fault segment, as shown by the cascading behavior of events (e.g., Salman et al, 2020;Sianipar et al, 2022aSianipar et al, , 2022b. It is worth noting that such cascading behavior also occurred in the 2007 Mw 6.3 and 6.4 Lake Singkarak earthquake doublet (Daryono et al, 2012;Salman et al, 2020).…”

Regional Finite-Fault Source Model for Development of Ground Motion Attenuation Relationship in Sichuan, China

“…Other parameters are local ones, which mainly describe the distribution characteristics of the slip on the rupture plane of the source. Sianipar et al [14] proposed an asperity model for earthquake source simulation, where the slip on the fracture surface is 1.5 or more times larger than that of other parts. Based on the statistical analysis of the slip distribution data of the 2002-2009 Sumbawa (Indonesia) earthquakes, the roughness parameters are extracted and the scaling law of local source parameters is established.…”