A review of the rupture characteristics of the 2011 Tohoku-oki Mw 9.1 earthquake

• Published in: Tectonophysics Vol. 733; pp. 4 - 36
• Main Author: Lay, Thorne
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 09.05.2018; Elsevier BV
• Subjects: 2011 Tohoku-oki earthquake; Bottom pressure; Broadband; Computational fluid dynamics; Creep rupture strength; Deformation; Dislocation models; Earthquake physics; Earthquakes; Fault friction; Fault slip distribution; Fault zones; Finite-source model; Fluids; Global positioning systems; GPS; Ground displacements; Heating; In situ measurement; Japan subduction zone; Megathrust faulting; Morphology; Ocean bottom; Ocean floor; Oceanic trenches; Offshore; Plate boundaries; Pressure sensors; Regions; Rupture parameters; Rupturing; Satellite navigation systems; Sea level; Sea level measurement; Sea level measurements; Seafloor geodesy; Sediments; Seismic activity; Shear stress; Slip; Slumping; Stations; Subduction; Subduction (geology); Subduction zones; Thrust bearings; Tsunami generation; Tsunamis; Viscoelasticity; Japan subduction zone; 2011 Tohoku-oki earthquake; Earthquake physics; Fault slip distribution; Seafloor geodesy; Fault friction; Megathrust faulting; Rupture parameters; Ground displacements; Tsunami generation; Finite-source model
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2017.09.022

The 2011 March 11 Tohoku-oki great (Mw 9.1) earthquake ruptured the plate boundary megathrust fault offshore of northern Honshu with estimates of shallow slip of 50m and more near the trench. Non-uniform slip extended ~220km across the width and ~400km along strike of the subduction zone. Extensive data provided by regional networks of seismic and geodetic stations in Japan and global networks of broadband seismic stations, regional and global ocean bottom pressure sensors and sea level measurement stations, seafloor GPS/Acoustic displacement sites, repeated multi-channel reflection images, extensive coastal runup and inundation observations, and in situ sampling of the shallow fault zone materials and temperature perturbation, make the event the best-recorded and most extensively studied great earthquake to date. An effort is made here to identify the more robust attributes of the rupture as well as less well constrained, but likely features. Other issues involve the degree to which the rupture corresponded to geodetically-defined preceding slip-deficit regions, the influence of re-rupture of slip regions for large events in the past few centuries, and relationships of coseismic slip to precursory slow slip, foreshocks, aftershocks, afterslip, and relocking of the megathrust. Frictional properties associated with the slip heterogeneity and in situ measurements of frictional heating of the shallow fault zone support low stress during shallow sliding and near-total shear stress drop of ~10–30MPa in large-slip regions in the shallow megathrust. The roles of fault morphology, sediments, fluids, and dynamical processes in the rupture behavior continue to be examined; consensus has not yet been achieved. The possibility of secondary sources of tsunami excitation such as inelastic deformation of the sedimentary wedge or submarine slumping remains undemonstrated; dislocation models in an elastic continuum appear to sufficiently account for most mainshock observations, although afterslip and viscoelastic processes remain contested. •The rupture process of the 2011 Tohoku Mw 9.1 earthquake is reviewed.•Seismic, geodetic, seafloor, tsunami, and drill hole information is considered.•Joint inversions of various data now provide consistent models for coseismic slip.•Rupture extended to the trench with 50m or more slip near 38.2°N.•The stress drop may have totally relaxed elastic shear stress in large slip areas.