Slip Partitioning by Elastoplastic Propagation of Oblique Slip at Depth

Bowman, D. D.; King, Geoffrey; Tapponnier, Paul

doi:10.1126/science.1082180

Cited by 94 publications

(90 citation statements)

References 19 publications

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“…The term "slip partitioning" is used to describe oblique motion along a fault system that is accommodated on two or more faults with different mechanisms (Fitch 1972;McCaffrey 1992;Jones and Wesnousky 1992;Bowman et al 2003). Slip Arrows point along fault trace.…”

Section: Schematic Illustrationmentioning

confidence: 99%

Slip-partitioned surface ruptures for the Mw 7.0 16 April 2016 Kumamoto, Japan, earthquake

Toda

Kaneda

Okada

et al. 2016

Earth Planets Space

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An ENE-trending ~30-km-long surface rupture emerged during the Mw = 7.0 16 April 2016 Kumamoto earthquake along the previously mapped Futagawa and northern Hinagu faults. This included a previously unknown 5-km-long fault within the Aso Caldera, central Kyushu. The rupture zone is mostly composed of right-lateral slip sections, with a maximum of 2-m coseismic slip. One of the noteworthy features we observed in the field are ~10-km-long segmented normal fault scarps, dipping to the northwest, along the previously mapped Idenokuchi fault, 1.2-2.0 km south of and subparallel to the Futagawa fault. The maximum amount of coseismic throw on the Idenokuchi fault is ~2 m, which is nearly equivalent to the maximum slip on the strike-slip rupture. The locations and slip motions of the 2016 rupture are also manifested as interferogram fringe offsets in InSAR images. Together with geodetic and seismic inversions of subsurface fault slip, we present a schematic structural model where oblique motion occurred on a northwest-dipping subsurface fault and the slip is partitioned at the surface into strike-slip and normal fault scarps. Our simple dislocation model demonstrates that this bifurcation into pure strike-slip and normal faults likely occurs for optimally oriented failure near the surface. The Kumamoto case, with detailed geological observations and geophysical models, would be the second significant slip-partitioned earthquake around the globe. It provides an important insight into scale-and depth-dependent stress heterogeneity and an implication to a proper estimate of seismic hazard in complex and broad multiple fault strands.

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Section: Schematic Illustrationmentioning

confidence: 99%

Slip-partitioned surface ruptures for the Mw 7.0 16 April 2016 Kumamoto, Japan, earthquake

Toda

Kaneda

Okada

et al. 2016

Earth Planets Space

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“…Here we expect weathered, often unconsolidated material which deforms differently. Further-3 a c c e p t e d more, complexity of surface and shallow rupture is often associated with slip partitioning between pure strike-slip and dip-slip modes originating in a deep oblique-slip master fault (Bowman et al, 2003). Expressions of such complexities at the surface are the development of different fault strands, positive and negative flower structures, pull-apart basins, pressure ridges etc.…”

Section: Introductionmentioning

confidence: 99%

Shallow architecture of the Wadi Araba fault (Dead Sea Transform) from high-resolution seismic investigations

et al. 2007

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In a high-resolution small scale seismic experiment we investigated the shallow structure of the Wadi Araba Fault (WAF), the principal fault strand of the Dead Sea Transform System between the Gulf of Aqaba/Eilat and the Dead Sea. The experiment consisted of 8 sub-parallel 1 km long seismic lines crossing the WAF. The recording station spacing was 5 meters and the source point distance was 20 m.The first break tomography yields insight into the fault structure down to a depth Often the superficial sedimentary layers are bent upward close to the WAF. Our results indicate that this section of the fault (at shallow depths) is characterized by a transpressional regime. We detected a 100 to 300 m wide heterogeneous zone of deformed and displaced material which, however, is not characterized by low seismic velocities at a larger scale. At greater depth the geophysical images indicate a blocked cross-fault structure. The structure revealed, fault cores not wider than 10 m, are consistent with scaling from wear mechanics and with the low loading to healing ratio anticipated for the fault.

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“…Field measurements indicate that the Pengguan fault was almost complete dip slip, while the Beichuan fault accommodated only slightly more dip slip than strike slip. Slip partitioning is a process by which oblique motions are accommodated in the near surface, with lateral displacements occurring on steeply dipping strike-slip faults and dip slip occurring on more shallowly dipping faults (e.g., Gaudemer et al, 1995;Bowman et al, 2003). In the case of the Wenchuan earthquake, the slip partitioning was not perfect: while the shallowly dipping Pengguan fault did rupture with dip slip, the steeply dipping Beichuan fault is not vertical and accommodated mixed strike-slip and dip-slip motion.…”

Section: Character Of the Wenchuan Rupturementioning

confidence: 99%

Structural Setting of the 2008 Mw 7.9 Wenchuan, China, Earthquake

Hubbard

Shaw

Klinger

2010

Bulletin of the Seismological Society of America

167

174

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International audienceThe 2008 M w 7.9 Wenchuan earthquake ruptured an imbricate thrust system in the Longmen Shan range, which forms the eastern boundary of the Tibetan Plateau. We use seismic reflection data and surface geology to construct geologic cross sections and a three-dimensional (3D) fault model in the range front. The rupture was complex, with slip on both the steeply dipping Beichuan fault and the more shallowly dipping Pengguan fault, which appear to merge at depth. In contrast, only the Beichuan fault ruptured in the north, with the transition near a lateral fault offset. Thus, the earthquake involved multiple thrust splays and breached a significant segment boundary. To investigate the tectonic setting of the earthquake, we extend our previous measurements of crustal shortening (Hubbard and Shaw, 2009) into the interior of the range and show that shortening correlates with topography. This suggests that upper-crustal shortening can produce the high topography of the Longmen Shan without calling on other uplift mechanisms. Based on this understanding, we model the thrust belt as a critical taper wedge, to assess what rock and fault strengths are required to explain the topographic slopes within the range front and basin. The low taper within the basin is consistent with a weak detachment (δ f ≈ 0:1), while a slightly stronger (δ f ≈ 0:3–0:4) detachment is necessary to explain the higher taper of the range front. This difference may relate to the localization of the detachment within a Triassic evaporite sequence within the basin, while the faults beneath the range front are rooted in Precambrian metasedimentary or igneous rocks. Critical taper theory implies that shortening in the range front where the 2008 Wenchuan earthquake occurred is many times greater than in the basin, consistent with our shortening measurements. We examine the implications of these findings for seismic hazard assessment in the region and in other active mountain belts around the world

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Slip Partitioning by Elastoplastic Propagation of Oblique Slip at Depth

Cited by 94 publications

References 19 publications

Slip-partitioned surface ruptures for the Mw 7.0 16 April 2016 Kumamoto, Japan, earthquake

Slip-partitioned surface ruptures for the Mw 7.0 16 April 2016 Kumamoto, Japan, earthquake

Shallow architecture of the Wadi Araba fault (Dead Sea Transform) from high-resolution seismic investigations

Structural Setting of the 2008 Mw 7.9 Wenchuan, China, Earthquake

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