Fault geometry and slip distribution of the 2008<i>M</i><sub>w</sub>7.9 Wenchuan, China earthquake, inferred from GPS and InSAR measurements

Wan, Yizhao; Shen, Zheng‐Kang; Bürgmann, Roland; Sun, Jianbao; Wang, Min

doi:10.1093/gji/ggw421

Cited by 47 publications

(48 citation statements)

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“…Inversions of teleseismic waveforms (e.g., Xu, Koper, et al, ; Zhang et al, ) indicate that the rupture zone coincides with the Yingxiu‐Beichuan fault, extending about 300 km from southwest of Yingxiu to north of Qingchuan. The coseismic slip models from geodetic studies using GPS and InSAR data (e.g., Shen et al, ; Tong et al, ; Wan et al, ) have results similar to that of the seismic studies, suggesting a ~300‐km long rupture along the Longmen Shan fault zone. Both seismic and geodetic studies inferred a subsurface rupture length of 300–310 km, coinciding with the ~310‐km long distribution of aftershocks (Figure ).…”

Section: Discussionmentioning

confidence: 70%

“…Northeast of Donghekou, field investigations did not reveal any evidence for a major surface break and only small open fissures and ground cracks were observed in some places, further confirming that the surface rupture must have stopped somewhere southwest of Donghekou. However, GPS and InSAR data (Hashimoto et al, ; Wan et al, ; Xu, Liu, et al ) together with the analysis of the aftershock distribution (Chen et al, ; Hu et al, ; Huang et al, ) suggest that the rupture most likely continued northeastward to the north of the Qingchuan fault (Figure ). Based on this information, we are convinced that there must be a fault that had not been previously recognized extending northeastward that was activated at depth during the Wenchuan earthquake.…”

Section: Fault Geometry At the Northeastern Rupture Terminationmentioning

confidence: 99%

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Fault Geometries and Structures Associated With the Rupture Endpoints of the 2008Mw7.9 Wenchuan Earthquake, Eastern Tibet Plateau, China

Wei

2019

Tectonics

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The 2008 Wenchuan earthquake (Mw 7.9) initiated at the southern part of the Yingxiu‐Beichuan fault of the Longmen Shan fault zone, eastern Tibet Plateau. The earthquake rupture propagated northeast for ~300 km, producing dextral‐thrust slip along the fault zone. Numerous studies have documented the characteristics of the rupture zone; however, the exact endpoints and the termination structures at both ends remain poorly constrained. On the northeasternmost rupture section, the aftershock distribution extends ~50 km along strike past the end of the observed surface rupture, suggesting that the rupture may extend northeastward at depth. Our field observations show that the aftershock zone follows a NE‐trending linear trace indicative of an active fault at the surface and confirm that the Qingchuan fault, which is one of the faults of the northeastern Longmen Shan fault zone and is reported to have ruptured during the 2008 earthquake by some studies, did not rupture during the Wenchuan earthquake. Detailed investigations show that the rupture terminated at an area between the Qingchuan and the Bahai‐Yuquanba faults where these two faults bound a 10‐ to 20‐km wide mountain block. To the southwest, the southwesternmost end of the Wenchuan earthquake rupture zone terminated south of Sanjiang, where a NE‐trending 50‐cm high fault scarp marks the endpoint of the surface rupture. Our study suggests that fault step overs at the northeastern and southwestern segments may have acted as a barrier to rupture propagation and thus play an important role in controlling the rupture propagation but were not critical in terminating the rupture, whereas the cross structures and/or stratigraphy (complex or massifs) in the northeastern and southwestern rupture endpoints area appear to have controlled the rupture termination.

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Section: Discussionmentioning

confidence: 70%

Section: Fault Geometry At the Northeastern Rupture Terminationmentioning

confidence: 99%

Fault Geometries and Structures Associated With the Rupture Endpoints of the 2008Mw7.9 Wenchuan Earthquake, Eastern Tibet Plateau, China

Wei

2019

Tectonics

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“…Using the maximum likelihood evaluation equation, we can get the following Eq. (7) (Jackson, 1979;Jackson and Matsu'ura, 1985;Shen et al, 1994;Wan et al, 2008c;Wan et al, 2015Wan et al, , 2017,…”

Section: Methods Of Inversionmentioning

confidence: 99%

“…If the corresponding diagonal element is 1, then the solution of the amount of slip is determined completely by the observed data (triangulation data and leveling data). If the corresponding diagonal element is 0, then the resolution of the solution from the observed data is zero and the solution is determined entirely from the smooth constraint (Wan et al, 2017). In this study, the surface displacement of each uniform slip on sub-fault is calculated using the analytical expression of Okada (1992).…”

Section: Methods Of Inversionmentioning

confidence: 99%

Rupture Distribution of the 1976 Tangshan Earthquake Sequence Inverted From Geodetic Data

Wan

Yong-Kui

Zhi-Tong

et al. 2017

Chinese J of Geophysics

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The Tangshan 1976 M 7.8 earthquake was followed by two large aftershocks (the Luanxian M 7.1 earthquake and the Ninghe M 6.9 earthquake). The earthquake sequence occurred in an area with good geodetic observation, and the horizontal and vertical co-seismic displacements were obtained by triangulation net and leveling net. In this study, by using raw leveling data (not the subsidence image processed from raw leveling data) and triangulation observation data, we obtain the rupture distribution of strike slip and dip slip component on seismogenic faults. The geometry and size of the seismic faults of the Luanxian and Ninghe earthquake are considered in our model construction. The result shows that the seismic fault of the Tangshan mainshock manifested right-lateral strike slip with a maximum value greater than 6 m in the southern segment. The strike slip component on the northern segment is much less than that of the southern segment. The total seismic moment of the Tangshan mainshock is 2.58×10 20 N·m, which is consistent with that determined by seismic waves. The seismic fault of the Luanxian earthquake shows as a left-lateral normal fault with total moment of 4.95×10 19 N·m. The seismic fault of the Ninghe earthquake shows as a left-lateral normal fault with total moment of 3.94×10 19 N·m, which is an order of magnitude greater than the moment determined by seismic waveform. It is so inferred that the aseismic slip of the Tangshan earthquake occurred on the western part of the Ninghe earthquake fault, demonstrated nearly normal fault property, which is of great significances for geodynamic process and mechanism of aftershock occurrence after the Tangshan earthquake.

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“…This slip distribution compares very well with the surface break observed along the rupture zone [60]. More recent studies have determined fault slip distribution using the observed GPS coseismic displacements as well as interferometric synthetic aperture radar (InSAR) data-e.g., the 1999 Mw 7.6 Chi-Chi Taiwan earthquake [61], the 2008 Mw 7.9 Wenchuan, China earthquake [62] and the 2016 Kumamoto earthquake [63]; and Lidar data e.g., the 1999 Mw 7.1 Hector Mine Earthquake, California [64]. All these studies have shown the variety and complexity of slip distribution during major earthquakes, ranging from estimated slip being highest in the epicentral region and tapers away [64], to much more complex distributions where fault rupture style changes along strike, fault slip peaks near the surface and peak slips are located around fault geometric complexities [62].…”

Section: Lateral Displacement and Slip Distributionsmentioning

confidence: 99%

Three-Dimensional Growth of Flexural Slip Fault-Bend and Fault-Propagation Folds and Their Geomorphic Expression

Bernal¹,

Hardy

Gawthorpe³

2018

Geosciences

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Abstract:The three-dimensional growth of fault-related folds is known to be an important process during the development of compressive mountain belts. However, comparatively little is known concerning the manner in which fold growth is expressed in topographic relief and local drainage networks. Here we report results from a coupled kinematic and surface process model of fault-related folding. We consider flexural slip fault-bend and fault-propagation folds that grow in both the transport and strike directions, linked to a surface process model that includes bedrock channel development and hillslope diffusion. We investigate various modes of fold growth under identical surface process conditions and critically analyse their geomorphic expression. Fold growth results in the development of steep forelimbs and gentler, wider backlimbs resulting in asymmetric drainage basin development (smaller basins on forelimbs, larger basins on backlimbs). However, topographies developed above fault-propagation folds are more symmetric than those developed above fault-bend folds as a result of their different forelimb kinematics. In addition, the surface expression of fault-bend and fault-propagation folds depends both on the slip distribution along the fault and on the style of fold growth. When along-strike plunge is a result of slip events with gently decreasing slip towards the fault tips (with or without lateral propagation), large plunge-panel drainage networks are developed at the expense of backpanel (transport-opposing) and forepanel (transport-facing) drainage basins. In contrast, if the fold grows as a result of slip events with similar displacements along strike, plunge-panel drainage networks are poorly developed (or are transient features of early fold growth) and restricted to lateral fold terminations, particularly when the number of propagation events is small. The absence of large-scale plunge-panel drainage networks in natural examples suggests that the latter mode of fold growth may be more common. The advective component of deformation (implicit in kink-band migration models of fault-bend and fault-propagation folding) exerts a strong control on drainage basin development. In particular, as drainage lengthens with fold growth, more linear, parallel drainage networks are developed as compared to the dendritic patterns developed above simple uplifting structures. Over the 1 Ma of their development the folds modelled here only attain partial topographic equilibrium, as new material is continually being advected through active axial surfaces on both fold limbs and faults are propagating in both the transport and strike directions. We also find that the position of drainage divides at the Earth's surface has a complex relationship to the underlying fold axial surface locations.

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Fault geometry and slip distribution of the 2008M_w7.9 Wenchuan, China earthquake, inferred from GPS and InSAR measurements

Cited by 47 publications

References 67 publications

Fault Geometries and Structures Associated With the Rupture Endpoints of the 2008Mw7.9 Wenchuan Earthquake, Eastern Tibet Plateau, China

Fault Geometries and Structures Associated With the Rupture Endpoints of the 2008Mw7.9 Wenchuan Earthquake, Eastern Tibet Plateau, China

Rupture Distribution of the 1976 Tangshan Earthquake Sequence Inverted From Geodetic Data

Three-Dimensional Growth of Flexural Slip Fault-Bend and Fault-Propagation Folds and Their Geomorphic Expression

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Fault geometry and slip distribution of the 2008Mw7.9 Wenchuan, China earthquake, inferred from GPS and InSAR measurements

Cited by 47 publications

References 67 publications

Fault Geometries and Structures Associated With the Rupture Endpoints of the 2008Mw7.9 Wenchuan Earthquake, Eastern Tibet Plateau, China

Fault Geometries and Structures Associated With the Rupture Endpoints of the 2008Mw7.9 Wenchuan Earthquake, Eastern Tibet Plateau, China

Rupture Distribution of the 1976 Tangshan Earthquake Sequence Inverted From Geodetic Data

Three-Dimensional Growth of Flexural Slip Fault-Bend and Fault-Propagation Folds and Their Geomorphic Expression

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Resources

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Fault geometry and slip distribution of the 2008M_w7.9 Wenchuan, China earthquake, inferred from GPS and InSAR measurements