Topography and the shallow slip deficit inference

Thompson, T. B.; Meade, Brendan J.

doi:10.31223/osf.io/puz84

Cited by 2 publications

(2 citation statements)

References 18 publications

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“…This suggests the SSD is overestimated when near‐field data are missing. Finally, setting aside the effect of local topography by using half‐space models may, in some cases, lead to an underestimation of coseismic shallow slip (Thompson & Meade, 2018). Recent studies thus showed that the modeling procedure itself may lead to overestimate shallow slip deficit but were however unable to bring this discrepancy to zero (Marchandon et al, 2018; Xu et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Fault Geometry and Slip Distribution of the 2013 Mw 7.7 Balochistan Earthquake From Inversions of SAR and Optical Data

2020

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The 2013 Mw 7.7 Balochistan earthquake ruptured the Hoshab fault (Pakistan) over 200 km. It was dominated by left‐lateral slip, with a secondary reverse component. By combining optical (SPOT 5 and Landsat 8) and radar satellite data (RADARSAT‐2 and TerraSAR‐X ScanSAR), we derive the 3‐D coseismic displacement field and the slip distribution. Our modeling strategy involves two successive inversions allowing to explore first the fault geometry and then slip distribution. Following a statistical analysis of the coseismic surface trace, the fault is discretized into 16 segments. To determine the dip angle and down‐dip width of the segments, we then perform a non‐linear elastic inversion of the geodetic data set. Using output of this model, we prescribe the fault geometry and linearly invert for slip at depth with refined discretization. Results show a decrease of the fault dip, reaching 50° in the central part of the fault that structurally connects the two sub‐vertical terminations dipping at >70°. The distribution of strike‐slip forms a shallow continuous patch (0–8 km) that peaks at 12.7 m of slip near the epicenter. Reverse slip is distributed on several patches and becomes shallower near the southern termination, where it peaks at 5.7 m. Our model shows an absence of shallow slip deficit (SSD), as for other Mw 7.5 + strike‐slip earthquakes elsewhere, hence suggesting that SSD is only found for lesser magnitude earthquakes. We speculate that moment magnitude is a key element in the occurrence of SSD.

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Section: Discussionmentioning

confidence: 99%

Fault Geometry and Slip Distribution of the 2013 Mw 7.7 Balochistan Earthquake From Inversions of SAR and Optical Data

2020

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“…Our inversions account for the uncertainty in geometry and solve for the degree of smoothing where distributed slip is used (sections 3.4 and 4). However, we do not account for any other uncertainties in the forward model, such as errors in elastic structure (Duputel et al, 2014;Ragon et al, 2018) or those introduced by failing to account for topography (Ben Thompson & Meade, 2018;Wang & Fialko, 2018). Inclusion of such model errors would increase the final uncertainties in our results.…”

Section: Methodsmentioning

confidence: 99%

Constraints on the Geometry and Frictional Properties of the Main Himalayan Thrust Using Coseismic, Postseismic, and Interseismic Deformation in Nepal

et al. 2020

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The geometry and frictional properties of a fault system are key parameters required to understand its seismic behavior. The Main Himalayan Thrust in Nepal is the type example of a continental megathrust and forms part of a fault system which accommodates a significant fraction of India‐Eurasia convergence. Despite extensive study of this zone of shortening, the geometry of the fault system remains controversial. Here, we use interseismic, coseismic, and postseismic geodetic data in Nepal to investigate the proposed downdip geometries. We use interseismic and coseismic data from previous studies, acquired before and during the 2015 Mw 7.8 Gorkha earthquake. We then supplement these by processing our own postseismic deformation data, acquired following the Gorkha earthquake. We find that kinematic modeling of geodetic data alone cannot easily distinguish between the previously proposed geometries. We therefore develop a mechanical joint coseismic‐postseismic slip inversion which simultaneously solves for the distribution of coseismic slip and rate‐strengthening friction parameters. We run this inversion using the proposed geometries and find that they are all capable of explaining the majority of geodetic data. We find values for the rate parameter, a, from the rate‐and‐state friction law that are between 0.8 and 1.6×10−3, depending on the geometry used. These values are in agreement with results from laboratory studies and those inferred from other earthquakes. We suggest that the limitations of earthquake cycle geodesy partly explain the continued controversy over the geometry and role of various faults in the Nepal Himalaya.

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Topography and the shallow slip deficit inference

Cited by 2 publications

References 18 publications

Fault Geometry and Slip Distribution of the 2013 Mw 7.7 Balochistan Earthquake From Inversions of SAR and Optical Data

Fault Geometry and Slip Distribution of the 2013 Mw 7.7 Balochistan Earthquake From Inversions of SAR and Optical Data

Constraints on the Geometry and Frictional Properties of the Main Himalayan Thrust Using Coseismic, Postseismic, and Interseismic Deformation in Nepal

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