Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data

Panet, I.; Bonvalot, Sylvain; Narteau, C.; Rémy, Dominique; Lemoine, Jean‐Michel

doi:10.1038/s41561-018-0099-3

Cited by 53 publications

(84 citation statements)

References 41 publications

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“…Compared with the gradient measurements by the GOCE satellite (Fuchs et al, ), the GRACE‐derived gradients are sensitive to signals of larger spatial scale. In the study by Panet et al (), the gravitational gradients Vyy′ are calculated in a sequence of local coordinate systems, which are defined by azimuthally rotating the local north‐east‐down (NED) system by different angles θ , sequentially increasing from 20° to 55°, in order to match the strike of the plate boundary. Here the prime symbol indicates the gradient is calculated in a rotated local coordinate system

false{{\overset{x}{true}}^{'}, {\overset{y}{true}}^{'}, {\overset{z}{true}}^{'} false}

(Text S2).…”

Section: Methods and Resultsmentioning

confidence: 99%

“…We first analyze the same GRACE solution as used by Panet et al (), that is, Centre National d'Eutdes Spatiales/Groupe de Recherches de Géodésie Spatiale (CNES/GRGS) Release 03‐v1 (RL03‐v1) monthly gravity field spherical harmonic coefficients. The same

\overset{V_{y y}^{'}}{true}

components with spatial scale of 1,400 km are calculated as described by Panet et al ().…”

Section: Methods and Resultsmentioning

confidence: 99%

“…Based on a space‐time analysis of the GRACE gravitational gradients, Panet et al () infer a large transient in gravitational gradients around the subduction zone of NE Japan, which started a couple of months before the 2011 mainshock and has a large spatial scale exceeding 1,000 km. The detected transient is equivalent to the effect of a M w 8.4 normal‐faulting earthquake at >250‐km depth (Panet et al, ). Previously, no large‐scale deformation transients have been reported by analyses of various geodetic measurements, including GRACE gravity (Han et al, ; Matsuo & Heki, ; Wang et al, ) and high‐precision GPS, which allows the measurement of deformation with subcentimeter precision (Yokota & Koketsu, ).…”

Section: Introductionmentioning

confidence: 99%

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Statistical Significance of Precursory Gravity Changes Before the 2011 M_w 9.0 Tohoku‐Oki Earthquake

Wang

Bürgmann

2019

Geophysical Research Letters

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It is of paramount importance to independently assess the spatiotemporal uniqueness of a proposed regional precursor initiated a few months before the 2011 Mw 9.0 Tohoku‐Oki earthquake. The precursor has been inferred from GRACE‐derived gravitational gradient changes and has been interpreted as a large‐scale aseismic movement of the subducting plate along the Japan Trench. We design a hypothesis test, which enables the rigorous assessment of the statistical significance of short‐term gradient anomalies at any time in any place and the quantitative comparison of the resolved anomalies with the proposed precursory signal. We find that the proposed precursory changes are not statistically unique either in time or in space. Therefore, the precursor cannot be attributed to the proposed dynamic acceleration of the subduction process. Instead, such transient features more likely represent temporally correlated GRACE observation errors or signals associated with other processes.

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false{{\overset{x}{true}}^{'}, {\overset{y}{true}}^{'}, {\overset{z}{true}}^{'} false}

(Text S2).…”

Section: Methods and Resultsmentioning

confidence: 99%

\overset{V_{y y}^{'}}{true}

components with spatial scale of 1,400 km are calculated as described by Panet et al ().…”

Section: Methods and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Statistical Significance of Precursory Gravity Changes Before the 2011 M_w 9.0 Tohoku‐Oki Earthquake

Wang

Bürgmann

2019

Geophysical Research Letters

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“…As far as earthquake studies using satellite gravimetry are concerned, it is highly desirable to have finer spatial and temporal resolutions. For example, finer temporal resolution than the current monthly can better resolve the postseismic scenarios among different mechanisms or help identify possible preseismic signal of the type of spatial pattern discussed in Panet et al (). Existing GRACE data versions that are of shorter temporal sampling interval, such as the GRGS RL03 10‐day solutions, can be examined for certain detailed cases (such as the 2013 Okhotsk event), but preliminary results of such are affected by higher apparent noises.…”

Section: Discussionmentioning

confidence: 99%

Gravity Changes Due to Large Earthquakes Detected in GRACE Satellite Data via Empirical Orthogonal Function Analysis

Chao

Liau

2019

JGR Solid Earth

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We report on the seven largest earthquakes for which we can detect unequivocal coseismic signals in the time‐variable gravity (TVG) data of the GRACE (Gravity Recovery and Climate Experiment) satellite mission during the GRACE era of 2002–2017. After reducing the land‐hydrological effect according to model Global Land Data Assimilation System, we employ the empirical orthogonal function (EOF) analysis to solve for the spatial pattern and time history of the coherent (standing‐oscillation) modes, which provide in an objective manner an overall view of the spatiotemporal scenario. The solved EOF mode for an earthquake‐induced TVG typically features a spatial pattern (along with polarity) for the coseismic jump, in conjunction with the time series showing the jump (plus possible preseismic and postseismic variability). In all cases the earthquake EOF mode solutions match well with the least squares coseismic jump in both spatial pattern and amplitude and agree generally with previous reports in the literature. We conclude according to the examined cases that the lowest earthquake magnitude threshold that can be detected by GRACE is the Mw 8.3 of the 2013 deep‐focus Okhotsk event, which in fact provides a testable case where the TVG we observe versus the seismologically derived source models may reflect different aspects of the source mechanism under different timescales.

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“…On the Moon, gravity gradients reconstructed from the Gravity Recovery and Interior Laboratory gravity fields have evidenced elongated anomalies attributed to magmatic intrusions (Andrews‐Hanna et al, ). In the same way, a precise delineation of local to regional gravity variations associated to earthquakes has been obtained from reconstructions of time‐varying gravity gradients from Gravity Recovery and Climate Experiment (Dai et al, ; Fuchs et al, ; Panet et al, ). The differentiations involved in the definition of gravity gradients indeed leads to a high sensitivity to the spatial pattern of the gravity signals, especially for north‐south or east‐west aligned sources: These are originated at the larger scales of the mantle main structure, down to those of a local coastline concentrating ice depletion signals (Bouman et al, ).…”

Section: Introductionmentioning

confidence: 99%

An Analysis of Gravitational Gradients in Rotated Frames and Their Relation to Oriented Mass Sources

Panet

2018

JGR Solid Earth

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Many mass sources within the Earth and its fluid envelopes show elongated geometries, aligning with the orientations of plate boundaries and plate motions, coastlines, rivers, and drainage basins for instance. To enhance their identification and separation in global or regional gravity observations and models, a dedicated method based on gravitational gradients analysis is presented here. This approach provides a detailed description of the geographic pattern of the gravity variations, which are accurately mapped thanks to the regular spatial coverage of high‐accuracy satellite data and arise from lateral density changes within the planet. First, gravity gradients are defined at different spatial scales in spherical frames, which are rotated along the radial axis according to the orientation of the source. The sensitivity of these gradients to the mass distribution inside a spherical Earth is described and analytical expressions relating the source to the observable are introduced. Then, the gravity gradients responses at different spatial scales to flat, elementary mass sources located at the surface and at increasing depth are studied. Specifically, the paper investigates how a source width and orientation can be determined, for localized and oscillatory mass anomalies with different width‐to‐length aspect ratios. This theoretical case study aims at providing a basis for the analysis of more complex mass structures, when applying the presented method to static or time‐varying satellite gravity field models. It may help deciphering the nature of the gravity sources by the detection of meaningful geometries and orientations in the gravity field.

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Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data

Cited by 53 publications

References 41 publications

Statistical Significance of Precursory Gravity Changes Before the 2011 M_w 9.0 Tohoku‐Oki Earthquake

Statistical Significance of Precursory Gravity Changes Before the 2011 M_w 9.0 Tohoku‐Oki Earthquake

Gravity Changes Due to Large Earthquakes Detected in GRACE Satellite Data via Empirical Orthogonal Function Analysis

An Analysis of Gravitational Gradients in Rotated Frames and Their Relation to Oriented Mass Sources

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Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data

Cited by 53 publications

References 41 publications

Statistical Significance of Precursory Gravity Changes Before the 2011 Mw 9.0 Tohoku‐Oki Earthquake

Statistical Significance of Precursory Gravity Changes Before the 2011 Mw 9.0 Tohoku‐Oki Earthquake

Gravity Changes Due to Large Earthquakes Detected in GRACE Satellite Data via Empirical Orthogonal Function Analysis

An Analysis of Gravitational Gradients in Rotated Frames and Their Relation to Oriented Mass Sources

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Statistical Significance of Precursory Gravity Changes Before the 2011 M_w 9.0 Tohoku‐Oki Earthquake

Statistical Significance of Precursory Gravity Changes Before the 2011 M_w 9.0 Tohoku‐Oki Earthquake