Determination of the source parameters of the 2011 Tohoku-Oki earthquake from three-component pre-P gravity signals recorded by dense arrays in Japan

Abstract Dynamic earthquake rupture causes mass redistribution around the fault, and emitted propagating seismic waves are accompanied by bulk density perturbations. Both processes cause transient gravity changes prior to arrival of P-waves. Such pre-P signals have been detected in previous studies several large earthquakes. However, detections were limited vertical component signal owing high noise level horizontal records. In this study, we analyzed dense tiltmeter array data Japan search for components from 2011 Mw 9.1 Tohoku-Oki earthquake. Based on synthetic waveforms computed a realistic Earth model, stacked records identified that evidently exceeded level. We further performed waveform inversion analysis estimate source parameters. The data, combined with broadband seismometer yielded constraint dip angle magnitude ranges 11.5°–15.3° 8.75°–8.92°, respectively. Our results indicate three avoids intrinsic trade-off problem between moment determining mechanism shallow Pre-P open new observation window studies. Graphical