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| Titel |
The 2015 M7.2 Sarez, Central Pamir, Earthquake And The Importance Of Strike-Slip Faulting In The Pamir Interior: Insights From Geodesy And Field Observations |
| VerfasserIn |
Sabrina Metzger, Bernd Schurr, Lothar Ratschbacher, Tilo Schöne, Sofia-Katerina Kufner, Yong Zhang, Henriette Sudhaus |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151365
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| Publikation (Nr.) |
 EGU/EGU2017-15936.pdf |
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| Zusammenfassung |
| The Pamir mountain range, located in the Northwest of the India-Asia collision zone,
accommodates approximately one third of the northward advance of the Indian continent at
this longitude (i. e. ∼34 mm/yr) mostly by shortening at its northern thrust system.
Geodetic and seismic data sets reveal here a narrow zone of high deformation and M7+
earthquakes of mostly thrust type with some dextral strike-slip faulting observed,
too. The Pamir interior shows sinistral strike-slip and normal faulting indicating
north-south compression and east-west extension. In this tectonic setting the two
largest instrumentally recorded earthquakes, the M7+ 1911 and 2015 earthquake
events in the central Pamir occurred with left-lateral shear along a NE-SW rupture
plane.
We present the co-seismic deformation field of the 2015 earthquake observed by radar
satellite interferometry (InSAR), SAR amplitude pixel offsets and high-rate Global
Positioning System (GPS). The InSAR and pixel offset results suggest a 50+ km long rupture
with sinistral fault offsets at the surface of more than 2 m on a yet unmapped fault trace of the
Sarez Karakul Fault System (SKFS). A distributed slip model with a data-driven slip patch
resolution yields a sub-vertical fault plane with a strike of N39.5 degrees and a rupture area of
∼80 x 40 km with a maximum slip of 2 m in the upper 10 km of the crust near the surface
rupture.
Field observations collected some nine months after the earthquake confirm the rupture
mechanism, surface trace location and fault offset measurements as constrained by geodetic
data. Diffuse deformation was observed across a 1-2 km wide zone, hosting primary fractures
sub-parallel to the rupture strike with offsets of 2 m and secondary, en echelon fractures
including Riedel shears and hybrid fractures often related to gravitational mass
movements.
The 1911 and 2015 earthquakes demonstrate the importance of sinistral strike-slip
faulting on the SKFS, contributing both to shear between the western and eastern Pamir and
westward extrusion of critically thickened Pamir crust into the Tajik depression. Shear may
also be transferred from below, where the tip of the Indian indenter is thought to have
underthrusted the Pamir. |
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