Intense foreshock swarm preceding the 2019 MW 6.5 Ambon (Seram, Indonesia) earthquake and its implication for the earthquake nucleation process

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

“…The Mw 5.1 foreshock was located very close to the initial break of the mainshock rupture, indicating a possible stochastic process in which the mainshock is the response to a perturbation imparted by the foreshock (Gomberg, 2018;Kato and Ben-Zion, 2021). However, other conceptual models that explain the nucleation mechanism of the mainshock are also possible, such as those characterised by a deterministic pre-slip nucleation process or a progressive localization framework (Gomberg, 2018;Kato and Ben-Zion, 2021;Sianipar et al, 2022a). Previous studies have found evidence of a nucleation phase and foreshocks associated with significant earthquakes (e.g., Ellsworth and Beroza, 1995;Kato and Ben-Zion, 2021).…”

“…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, 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).…”

Characterization of Fiber Bragg Grating Accelerometer for Underwater Vibration Detection

“…In Indonesia, natural events such as earthquakes occur quite frequently on several islands, including Jawa, (Supendi et al, 2022), Sulawesi (Jena et al, 2020), Kalimantan, Maluku (Sianipar et al, 2022), and other smaller islands (Ramdani et al, 2019). This is due to Indonesia's location surrounded by three tectonic plates: the Eurasian Plate, the Indo-Australian Plate, and the Pacific Plate (Wibowo et al, 2023).…”