Bayesian inversion for finite fault earthquake source models – II: the 2011 great Tohoku-oki, Japan earthquake

Minson, S. E.; Simons, M.; Beck, James L.; Ortega, F.; Jiang, Junle; Owen, S. E.; Moore, A. W.; Inbal, Asaf; Sladen, Anthony

doi:10.1093/gji/ggu170

Cited by 97 publications

(134 citation statements)

References 32 publications

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“…We find a source duration of approximately T 1 = 125 s, which is close to Minson et al [2014] estimates and slightly lower than other duration values Meng et al, 2011]. The second time scale for the Tohoku earthquake is T 2 = 11 s, but likely poorly constrained given that it is close to the cutoff frequency of our data bandwidth.…”

Section: /2016jb013105supporting

confidence: 69%

“…For earthquakes of M w ≥ 8, where a single "point-source depth" loses meaning due to the finite extent of the fault, we use the GCMT depths as the best representative depth as it should represent the depth of highest moment release. For the M w 9 2011 Tohoku event, we choose a focal depth of 16 km, which was found by Minson et al [2014] to be that of highest potency.…”

Section: Depth-phase Effects In Spectramentioning

confidence: 99%

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New perspectives on self‐similarity for shallow thrust earthquakes

2016

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Scaling of dynamic rupture processes from small to large earthquakes is critical to seismic hazard assessment. Large subduction earthquakes are typically remote, and we mostly rely on teleseismic body waves to extract information on their slip rate functions. We estimate the P wave source spectra of 942 thrust earthquakes of magnitude Mw 5.5 and above by carefully removing wave propagation effects (geometrical spreading, attenuation, and free surface effects). The conventional spectral model of a single‐corner frequency and high‐frequency falloff rate does not explain our data, and we instead introduce a double‐corner‐frequency model, modified from the Haskell propagating source model, with an intermediate falloff of f−1. The first corner frequency f1 relates closely to the source duration T1, its scaling follows M0∝T13 for Mw<7.5, and changes to M0∝T12 for larger earthquakes. An elliptical rupture geometry better explains the observed scaling than circular crack models. The second time scale T2 varies more weakly with moment, M0∝T25, varies weakly with depth, and can be interpreted either as expressions of starting and stopping phases, as a pulse‐like rupture, or a dynamic weakening process. Estimated stress drops and scaled energy (ratio of radiated energy over seismic moment) are both invariant with seismic moment. However, the observed earthquakes are not self‐similar because their source geometry and spectral shapes vary with earthquake size. We find and map global variations of these source parameters.

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Section: /2016jb013105supporting

confidence: 69%

Section: Depth-phase Effects In Spectramentioning

confidence: 99%

New perspectives on self‐similarity for shallow thrust earthquakes

2016

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“…4a), the largest coseismic stress rotation is the lower part of zone B and the rotation extends into the upper part of zone C. The Moho depth of the overriding plate is 30-35 km, shallowing toward the trench (Zhao et al 1994), meaning that much of the rotation is below the Moho depth. In contrast, the largest slip in most finite rupture models is in the upper part of zone B and in zone A (e.g., Shao et al 2011;Yagi and Fukahata 2011;Yamazaki et al 2011;Minson et al 2014), while the model of Ide et al (2011) places a second peak of slip at the base of zone C. For the Tohoku-Oki earthquake, the largest coseismic stress rotations therefore appear to occur at the down-dip edge of the shallow area of large slip. For the Sumatra earthquake (Fig.…”

Section: Resultsmentioning

confidence: 93%

The spatial distribution of earthquake stress rotations following large subduction zone earthquakes

Hardebeck

2017

Earth Planets Space

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Rotations of the principal stress axes due to great subduction zone earthquakes have been used to infer low differential stress and near-complete stress drop. The spatial distribution of coseismic and postseismic stress rotation as a function of depth and along-strike distance is explored for three recent M ≥ 8.8 subduction megathrust earthquakes. In the down-dip direction, the largest coseismic stress rotations are found just above the Moho depth of the overriding plate. This zone has been identified as hosting large patches of large slip in great earthquakes, based on the lack of high-frequency radiated energy. The large continuous slip patches may facilitate near-complete stress drop. There is seismological evidence for high fluid pressures in the subducted slab around the Moho depth of the overriding plate, suggesting low differential stress levels in this zone due to high fluid pressure, also facilitating stress rotations. The coseismic stress rotations have similar along-strike extent as the mainshock rupture. Postseismic stress rotations tend to occur in the same locations as the coseismic stress rotations, probably due to the very low remaining differential stress following the near-complete coseismic stress drop. The spatial complexity of the observed stress changes suggests that an analytical solution for finding the differential stress from the coseismic stress rotation may be overly simplistic, and that modeling of the full spatial distribution of the mainshock static stress changes is necessary.

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“…Using hr-GPS data in single inversion or joint inversion with other available data Bletery et al 2014) for the rupture process has been performed with a constant rupture velocity to obtain a consistent main slip asperity with a simple rupture feature up-dip of the hypocenter to the trench. A rupture model with freely varying rupture velocity for each subfault has been presented by Minson et al (2014) from joint inversion of geodetic data and tsunami data using a single-time-window method. In the present study, we use hr-GPS data in northeastern Japan and ocean bottom GPS/acoustic (OB-GPS) data to invert for the rupture process of the 2011 Mw 9.0 Tohoku-Oki earthquake.…”

Section: Introductionmentioning

confidence: 99%

Source process with heterogeneous rupture velocity for the 2011 Tohoku-Oki earthquake based on 1-Hz GPS data

Wang

Kato

Xiao-hong

et al. 2016

Earth Planets Space

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Abstract:A rupture model with varying rupture front expansion velocity for the March 11, 2011, Tohoku-Oki earthquake was obtained by the joint inversion of high-rate Global Positioning System (GPS) data and ocean bottom GPS/acoustic (OB-GPS) data. The inverted rupture velocity with a complex distribution gradually increases near the hypocenter and shows rapid rupture expansion at the shallowest part of the fault. The entire rupture process, which lasted 160 s, can be divided into three energy release stages, based on the moment rate function. The preferred slip model, showing a compatible relationship with aftershocks, has a primary asperity concentrated from the hypocenter to the trench and a small asperity located on the southern fault. Source time functions for subfaults and temporal rupture images suggest that repeated slips occurred in the primary rupture, which is consistent with that from seismic waveforms. Our estimated maximum slip and total seismic moment are ~65 m and 4.2 × 10 22 Nm (Mw 9.0), respectively. The large slip, stress drop, and rupture velocity are all concentrated at shallow depths, which indicates that the shallow part of the fault radiated high-frequency as well as low-frequency seismic waves.

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Bayesian inversion for finite fault earthquake source models – II: the 2011 great Tohoku-oki, Japan earthquake

Cited by 97 publications

References 32 publications

New perspectives on self‐similarity for shallow thrust earthquakes

New perspectives on self‐similarity for shallow thrust earthquakes

The spatial distribution of earthquake stress rotations following large subduction zone earthquakes

Source process with heterogeneous rupture velocity for the 2011 Tohoku-Oki earthquake based on 1-Hz GPS data

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