Integrated seismic source model of the 2021<i>M</i>7.1 Fukushima earthquake

SUMMARY We constructed an integrated rupture model of the 2021 Mw 7.1 Fukushima earthquake, intraplate by resolving both its spatiotemporal distribution slip-rate and high-frequency (∼1 Hz) radiations. analysed near-field seismic observations using a novel finite-fault inversion method that allows automatic parametrization teleseismic data from multiple arrays MUSIC backprojection (BP) enhances imaging resolution. The inverted slip obtained waveforms filtered in frequency band 0.02–0.2 Hz showed kinematic propagated along strike (∼35 km) dip directions (∼85 km), large-slip area was located southwest to hypocentre with maximum ∼1.03 m. Overall, no obvious frequency-dependent behaviours occurred during process due deep nucleation earthquake on heterogeneous fault where sizes asperities do not monotonically increase depth, which sheds light understanding dynamics earthquakes subduction zones. Both BP revealed general feature this southwestward updip directivity. A comparison BPs between indicates source–receiver geometry directivity effect may cause critical discrepancies different arrays. From temporal change stress around 2011 Tohoku-Oki 9.1 long-term dominance viscoelastic relaxation increased Coulomb failure function (CFF) 0.3–0.7 MPa, indicating occurrence has been likely promoted post-seismic deformation earthquake.