Distributed fault slip model for the 2011 Tohoku‐Oki earthquake from GNSS and GRACE/GOCE satellite gravimetry

Fuchs, M; Hooper, Andrew; Broerse, Taco; Bouman, J

doi:10.1002/2015jb012165

Cited by 19 publications

(16 citation statements)

References 45 publications

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“…To obtain a slip distribution from GRACE comparable to that obtained from GPS data, a higher spherical harmonic degree and lighter filtering will be necessary. Combining GRACE and GOCE without any filter may be an effective way to address this issue (Fuchs et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

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Co-seismic slip distribution of the 2011 Tohoku (MW 9.0) earthquake inverted from GPS and space-borne gravimetric data

Zhou

Cambiotti

Sun

et al. 2018

Earth and Planetary Physics

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Data obtained by GRACE (Gravity Recovery and Climate Experiment) have been used to invert for the seismic source parameters of megathrust earthquakes under the assumption of either uniform slip over an entire fault or a point‐like seismic source. Herein, we further extend the inversion of GRACE long‐wavelength gravity changes to heterogeneous slip distributions during the 2011 Tohoku earthquake using three fault models: (I) a constant‐strike and constant‐dip fault, (II) a variable dip fault, and (III) a realistically varying strike fault. By removing the post‐seismic signal from the time series, and taking the effect of ocean water redistribution into account, we invert for slip models I, II, and III using co‐seismic gravity changes measured by GRACE, de‐striped by DDK3 decorrelation filter. The total seismic moments of our slip models, with respective values of 4.9×1022 Nm, 5.1×1022 Nm, and 5.0×1022 Nm, are smaller than those obtained by other studies relying on GRACE data. The resulting centroids are also located at greater depths (20 km, 19.8 km, and 17.4 km, respectively). By combining onshore GPS, GPS‐Acoustic, and GRACE data, we obtain a jointly inverted slip model with a seismic moment of 4.8×1022 Nm, which is larger than the seismic moment obtained using only the GPS displacements. We show that the slip inverted from low degree space‐borne gravimetric data, which contains information at the ocean region, is affected by the strike of the arcuate trench. The space‐borne gravimetric data help us constrain the source parameters of a megathrust earthquake within the frame of heterogeneous slip models.

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Section: Discussionmentioning

confidence: 99%

“…In this regard, GRACE im-proves our understanding of the physics of the earthquake source. Most recently, Fuchs et al (2016) investigated the fault slip distribution for the 2011 Tohoku earthquake using data obtained using GPS, GRACE, and GOCE (the Gravity Field and Steady-State Circulation Explorer).…”

Section: Introductionmentioning

confidence: 99%

Co-seismic slip distribution of the 2011 Tohoku (MW 9.0) earthquake inverted from GPS and space-borne gravimetric data

Zhou

Cambiotti

Sun

et al. 2018

Earth and Planetary Physics

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“…Coseismic gravitational signals are sensitive to filtering used to suppress noise in GRACE observations, and some filtering choices may attenuate coseismic signals. This is of concern because recent studies have begun to use GRACE observations as geodetic constraints on coseismic slip models of the 2011 Tohoku‐Oki earthquake [e.g., Han et al ., , ; Cambiotti and Sabadini , , ; Dai et al ., , ; Fuchs et al ., ]. Topographic effects need to be included for this earthquake, and possibly for others in regions of steep topography in oceanic trenches.…”

Section: Discussionmentioning

confidence: 99%

“…GRACE observations have complemented other geodetic measurements of earthquake displacement (such as GPS, interferometric synthetic aperture radar, and terrestrial gravimetry), particularly in oceanic areas where terrestrial geodetic observations are difficult to obtain. Recently, GRACE data have been incorporated in fault slip inversion next to GOCE and GPS measurements [ Fuchs et al ., ]. GRACE gravimetry also serves as a good supplement to teleseismic wave data (from global seismic networks) to understand focal mechanisms and fault slip of very large earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Topographic effects on coseismic gravity change for the 2011 Tohoku‐Oki earthquake and comparison with GRACE

Chen

Wilson

2016

JGR Solid Earth

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We estimate gravity changes due to coseismic horizontal deformation and inclined bathymetry (referred to as topographic effects in this study) associated with the 2011 Tohoku‐Oki earthquake, using a layered half‐space dislocation model. As an approximation, we represent inclined topography with ramp‐body models in the near field of the earthquake and calculate topographic effects from both an inclined seafloor and Moho. The Moho effect partly compensates that from the seafloor. An additional contribution comes from seawater column variations as the sloped seafloor moves trenchward. Topographic effects are first‐order contributions to coseismic gravity changes for the 2011 Tohoku‐Oki earthquake. After 300 km Gaussian smoothing, comparable to the spatial resolution of the Gravity Recovery and Climate Experiment (GRACE), topographic effects create a dominantly negative gravity pattern with amplitudes up to 1.1 μGal for oceanic areas surrounding the epicenter. There are discrepancies between model predictions (−10.4 to +6.9 μGal) and GRACE observations (10.1 to +1.7 μGal). Errors in the adopted fault slip model and difficulties in separating coseismic and postseismic deformation may contribute to these, but topographic effects, currently neglected in dislocation models, are also responsible. Topographic effects ought to be included in coseismic fault slip and related gravity modeling for the 2011 Tohoku‐Oki earthquake and similar events in regions of steep topography.

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“…The GOCE mission has been proven successful for constructing regional geoid models combining with the EGM2008 and terrestrial gravity datasets [18,19], and can be used to study the lithospheric modeling, dynamic topography, and glacial isostatic adjustment [20][21][22][23]. However, a few studies have focused on inferring the coseismic gravity change signals from simulated data [24][25][26] or real GOCE observations [27][28][29].…”

Section: Introductionmentioning

confidence: 99%

GOCE-Derived Coseismic Gravity Gradient Changes Caused by the 2011 Tohoku-Oki Earthquake

Ding

Zhao

et al. 2019

Remote Sensing

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In contrast to most of the coseismic gravity change studies, which are generally based on data from the Gravity field Recovery and Climate Experiment (GRACE) satellite mission, we use observations from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) Satellite Gravity Gradient (SGG) mission to estimate the coseismic gravity and gravity gradient changes caused by the 2011 Tohoku-Oki Mw 9.0 earthquake. We first construct two global gravity field models up to degree and order 220, before and after the earthquake, based on the least-squares method, with a bandpass Auto Regression Moving Average (ARMA) filter applied to the SGG data along the orbit. In addition, to reduce the influences of colored noise in the SGG data and the polar gap problem on the recovered model, we propose a tailored spherical harmonic (TSH) approach, which only uses the spherical harmonic (SH) coefficients with the degree range 30–95 to compute the coseismic gravity changes in the spatial domain. Then, both the results from the GOCE observations and the GRACE temporal gravity field models (with the same TSH degrees and orders) are simultaneously compared with the forward-modeled signals that are estimated based on the fault slip model of the earthquake event. Although there are considerable misfits between GOCE-derived and modeled gravity gradient changes (ΔVxx, ΔVyy, ΔVzz, and ΔVxz), we find analogous spatial patterns and a significant change (greater than 3σ) in gravity gradients before and after the earthquake. Moreover, we estimate the radial gravity gradient changes from the GOCE-derived monthly time-variable gravity field models before and after the earthquake, whose amplitudes are at a level over three times that of their corresponding uncertainties, and are thus significant. Additionally, the results show that the recovered coseismic gravity signals in the west-to-east direction from GOCE are closer to the modeled signals than those from GRACE in the TSH degree range 30–95. This indicates that the GOCE-derived gravity models might be used as additional observations to infer/explain some time-variable geophysical signals of interest.

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Distributed fault slip model for the 2011 Tohoku‐Oki earthquake from GNSS and GRACE/GOCE satellite gravimetry

Cited by 19 publications

References 45 publications

Co-seismic slip distribution of the 2011 Tohoku (<i>M</i><sub>W</sub> 9.0) earthquake inverted from GPS and space-borne gravimetric data

Co-seismic slip distribution of the 2011 Tohoku (<i>M</i><sub>W</sub> 9.0) earthquake inverted from GPS and space-borne gravimetric data

Topographic effects on coseismic gravity change for the 2011 Tohoku‐Oki earthquake and comparison with GRACE

GOCE-Derived Coseismic Gravity Gradient Changes Caused by the 2011 Tohoku-Oki Earthquake

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