Attenuation Structure Beneath the 2022 M_W5.6 Cianjur Earthquake Seismogenic Zone: New Insights From a Local Temporary Seismograph Network

Abstract. The 2022 M_W5.6 West Java earthquake in Cianjur, Indonesia, generated strong ground motions and caused heavy casualties. In this study, we employed seismic attenuation tomography using data from a temporary local seismic network to investigate subsurface structures beneath the source region. Aftershock waveform data were analyzed using modified-Metropolis spectral matching to estimate t_P^* and t_S^* . Simul2023 was then used to obtain 3D Q_p and Q_s models, with the resolution assessed via checkerboard resolution tests, derivative weight sums, and diagonal resolution elements. The results revealed a prominent shallow low-Q zone above the mainshock and near Mount Gede-Pangrango, which is interpreted as sedimentary and volcaniclastic materials with elevated fluid contents, while a higher-Q zone was observed below a depth of ~6 km, corresponding to the seismogenic zone. The mainshock occurred near the low-Q (weak) and high-Q (rigid) transition, suggesting that this boundary may represent a mechanical interface that structured the aftershock distribution. Our findings indicate that attenuation contrasts provide useful constraints on crustal heterogeneity and may contribute to the understanding of earthquake processes in complex volcanic–tectonic settings.