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Rupture in the 2015 M7.8 Gorkha earthquake nucleated at the downdip edge of the Main Himalayan Thrust (MHT) near the transition from interseismic locking to aseismic creep beneath the Tibetan plateau, and propagated incompletely towards the Main Frontal Thrusts (MFT). Despite the imposition of a substantial static strain in the mid-décollement, afterslip on the MHT within a year of the earthquake had decayed to negligible levels. Earthquakes that incompletely rupture the MHT (7 < Mw < 7.9) have been relatively common in the past two centuries, and as a consequence heterogeneous patches of stored elastic strain must exist throughout the Himalaya similar to that emplaced by the Gorkha earthquake. We show that these patches of stored strain are not dissipated by creep or by subsequent updip earthquakes, with the possible exceptions of a sequence of moderate earthquakes to the west of the great 1950 Assam earthquake, and to the east of the Kangra 1905 earthquake. It is thus considered likely that mid-décollement strain newly imposed by the Gorkha earthquake, and other recent incomplete ruptures will be incorporated in the rupture of a future much larger earthquake. Incomplete ruptures (i.e. those that nucleate downdip but fail to rupture the frontal thrusts) appear to occur preferentially in parts of the central Himalaya characterized by relatively narrow transition regions of interseismic decoupling (

We developed a middle school earthquake science and hazards curriculum to promote earthquake awareness to students in the Central Asian country of Tajikistan. These materials include pre- and post-assessment activities, six science activities describing physical processes related to earthquakes, five activities on earthquake hazards and mitigation strategies, and a codification art/literacy project. This curriculum was implemented with 43 middle school students in Dushanbe, Tajikistan in the winter of 2008. We examine the effectiveness of each curriculum component in communicating the causes, effects, and mitigation strategies associated with earthquakes to young people, and find significant improvements in seismic and earthquake hazards literacy as a result of the program.

By combining global positioning system observations of surface displacements and the locations of aftershocks, we infer that the 8 October 2005 Kashmir earthquake occurred on multiple fault planes. Mean slip of ~5.1 m occurred on a rupture between Bagh and Balakot with strike 331[degrees] and dip 29[degrees]. Additional slip occurred at depth on a NNE-dipping fault plane extending WNW from Balakot, and on an intersecting nearly flat dislocation at ~5 km depth, forming an active wedge thrust. Both the simple fault plane and the blind wedge accommodate convergence between Peshawar and Leh, Ladakh, accumulating at 7 [+ or -] 2 mm/yr, suggesting a 680 [+ or -] 150 yr recurrence interval for Kashmir 2005-like events. Keywords: Kashmir earthquake, wedge thrust, Himalayan tectonics.

Author(s): Rebecca Bendick [1]; Roger Bilham (corresponding author) [1, 2]; Jeffrey Freymueller [3]; Kristine Larson [4]; Guanghua Yin The collision between India and Asia has been simulated with a variety [...]

At the northwestern tip of the India‐Asia collision zone, the Pamir orocline overrides the Tajik Depression and the Tarim Basin and collides with the Tian Shan. Currently, the Pamir's northern edge exhibits localized shortening rates of 13–19 mm/yr. While the eastern Pamir and the Tarim Basin move northward nearly en block, north‐south shortening decreases westward along the Pamir front into the Tajik Depression. In the northeastern Tajik Depression, the wedge‐shaped crustal sliver of the Peter the First Range is squeezed between the dextral‐transpressive Vakhsh and the sinistral‐transpressive Darvaz faults. Global Navigation Satellite System (GNSS) data collected along two densely surveyed profiles detail the kinematics of north‐south shortening and westward lateral extrusion in the northwestern Pamir. The 2016 campaign data suggest a short‐duration dextral‐slip activation of the Darvaz fault, which we interpret as a far‐field effect triggered by the 2015, Mw7.2 Sarez, Central Pamir earthquake. 2013–2015 interseismic GNSS velocities and kinematic modeling show that the Darvaz fault zone accommodates ~15 mm/yr sinistral shear and ~10 mm/yr fault‐normal extension below a locking depth of 9.0 + 0.4/−1.1 km. The Vakhsh fault shows shortening rates of 15 + 4/−2 mm/yr and dextral shear rates of 16 ±3 mm/yr. Jointly, these faults accommodate NW‐SE shortening and southwestward material flow out of the Peter the First Range into the Tajik Depression. Together with seismic and geologic data, our and published geodetic surveys showcase the prolonged interaction of shortening and lateral material flow out of a plateau margin. Plain Language Summary: The Pamir Mountains, Central Asia, are the result of the northward indentation of the Indian continent into Eurasia. In average, the Pamir Plateau is ~3,000 m higher than the adjacent Tajik Depression to the west. We present time‐series of high‐precision point positioning data that show in great detail how the upper crust of the Pamir is flowing out into the lower lying Tajik Depression. This westward transport occurs on shallow‐dipping, low‐friction sedimentary layers that reach surface at the beginning of the Tian Shan Mountains further north. These sediments accommodate a total slip of around 2 cm, which is extremely high for continent‐continent plate boundaries. In addition, our data observed a few centimeters of slip on the Darvaz fault that most probably was triggered by a large earthquake occurring in some 200 km distance. Such phenomena have so far rarely been observed. Key Points: New survey‐GNSS data record gravity‐driven, lateral material flow out of the Pamir Plateau and shortening of the Tajik Basin depositsThe Vakhsh fault accommodates 15 + 4/−2 mm/yr shortening and 16 ±3 mm/yr dextral shear, the Darvaz fault ~15 mm/yr sinistral shearThe 2015 Mw7.2 Sarez earthquake may have triggered ~2 cm of slip on the Darvaz fault reverse to its interseismic loading sense [ABSTRACT FROM AUTHOR]

The Pamir orogen, Central Asia, is the result of the ongoing northward advance of the Indian continent causing shortening inside Asia. Geodetic and seismic data place the most intense deformation along the northern rim of the Pamir, but the recent 7 December 2015, M w7.2 Sarez earthquake occurred in the Pamir's interior. We present a distributed slip model of this earthquake using coseismic geodetic data and postseismic field observations. The earthquake ruptured an ∼80 km long, subvertical, sinistral fault consisting of three right-stepping segments from the surface to ∼30 km depth with a maximum slip of three meters in the upper 10 km of the crust. The coseismic slip model agrees well with en échelon secondary surface breaks that are partly influenced by liquefaction-induced mass movements. These structures reveal up to 2 m of sinistral offset along the northern, low-offset segment of modeled rupture. The 2015 event initiated close to the presumed epicenter of the 1911 M w∼7.3 Lake Sarez earthquake, which had a similar strike-slip mechanism. These earthquakes highlight the importance of NE trending sinistral faults in the active tectonics of the Pamir. Strike-slip deformation accommodates shear between the rapidly northward moving eastern Pamir and the Tajik basin in the west and is part of the westward (lateral) extrusion of thickened Pamir plateau crust into the Tajik basin. The Sarez-Karakul fault system and the two large Sarez earthquakes likely are crustal expressions of the underthrusting of the northwestern leading edge of the Indian mantle lithosphere beneath the Pamir. [ABSTRACT FROM AUTHOR]

Calculation of earthquake scarp ages from scarp morphology usually assumes that scarp materials reach their angle of repose immediately after a rupture. However, observations of the 1959 Hebgen Lake, Montana, earthquake scarp and similar features worldwide confirm that scarps require a finite period of mass failure to reach the initial conditions for hillslope diffusion, so the age of features less than 1000 yr old cannot be accurately estimated with methods based only on the linear diffusion equation. We apply a numerical model of this interval of mass failure degradation to vertical initial-angle scarps from the 1959 rupture at Hebgen Lake, Montana. The mass failure rate coefficient, RM, ranges from 1.0 x 10-2 to 1.2 x 10-1 m · yr-1 for young scarps at Hebgen Lake and nine other locations, and has little or no dependence on climate conditions such as annual temperature range or average rainfall. Including an interval of mass failure gives more accurate age estimates where a scarp age is of the same order as the characteristic mass failure relaxation time of 10-1000 yr. [ABSTRACT FROM AUTHOR]