Preceding seismic activity and slow slip events in the source area of the 2011 Mw 9.0 Tohoku-Oki earthquake: a review

摘要: The 2011 Tohoku-Oki earthquake ruptured a large area of the megathrust east NE Japan. earthquake’s magnitude was 9.0, substantially larger than predicted. It is important to know what occurred in source prior this great improve understanding nucleation processes earthquakes and risk assessments subduction zones. Seafloor observation data revealed existence two extremely slip patches: one just updip mainshock hypocenter other 80–100 km north near trench axis. For 70–90 years before 2003, M > 6 events slips c. 7 on areas surrounding these patches. Seismic activity had increased since at least 2003 downdip portion earthquake. In addition, long-term accelerated slow decades About 1 month earthquake, event (SSE) took place relatively shallow depths between patches, accompanied by foreshock activity. Both foreshocks propagated from south toward southern patch. Two days an 7.3 associated postseismic began deep type seems have approximately half day after hypocenter. This again These long- short-term preceding seismic aseismic gradually reduced interplate coupling, shear stresses patches (i.e., strong asperity patches), finally led rupture