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Structural Interpretation and Geo-Hazard Assessment of a Locking Line, 2005 Kashmir Earthquake, Western Himalayas.

Jadoon, I. A. K. and Hinderer, Matthias and Kausar, A. B. and Qureshi, A. A. and Baig, M. S. and Basharat, M. and Frisch, W. (2015):
Structural Interpretation and Geo-Hazard Assessment of a Locking Line, 2005 Kashmir Earthquake, Western Himalayas.
In: Environmental Earth Sciences, Springer Link Berlin Heidelberg 2012, pp. 7587-7602, 73, (11), ISSN 1866-6280, [Online-Edition: http://link.springer.com/article/10.1007/s12665-014-3929-7],
[Article]

Abstract

The 08 October 2005, magnitude (Mw) 06 Kashmir earthquake occurred along the Balakot–Bagh fault (BBF) with about 30° dip toward NE in the internal part of the western Himalayas in north Pakistan. It was accompanied by a ground rupture of about 75 km with an average slip of about 5 m along the causative fault. The epicenter of the thrust was located at about 19 km to the NE of its surface trace in Muzaffarabad with about 11 km depth of the hypocenter. The geometry of the fault based on a structural cross section has allowed us to interpret it as a thrust restricted to a roof sequence along a triangle zone across the Hazara–Kashmir syntaxis (HKS). The triangle zone is occupied at depth by a wedge of the Higher Himalayan Sequence (HHS) in the core zone of the HKS. The core–wedge is bounded between the NE-dipping BBF and SE- to SW-dipping thrust stack of the Lesser Himalayan Sequence (LHS) along the northeastern and southwestern limb of the HKS, respectively. Based on surface geology, the overlapping BBF and MBT are interpreted to merge at depth in a roof thrust of Pre-Cambrian (Late Proterozoic) rocks above a duplex which is inferred to have a floor thrust in Early Proterozoic/Archean rocks. The core–wedge is located over a ramp which is connected to the floor thrust in the basement. The BBF is inferred to be active, at least since 1–0.5 Ma, with recurrence interval of about 625 ± 125 years. This out-of-sequence deformation is represented by linear seismicity, both along emergent and blind thrusts in the system, with likelihood of major events as a result of strain buildup due to slow convergence rates (~7 mm/year) in the region. Many towns located along the active fault trace were destroyed or largely damaged due to the earthquake. Major destruction of human dwellings and infrastructure occurred as a consequence of earthquake-triggered landslides, mostly along fault, high river terraces, and road cuts. To minimize future damages in earthquake-prone areas, several mitigation measures are suggested including: (1) avoiding new settlements near the fault trace and landslide susceptible areas, (2) establishment of new township schemes in relatively safer areas with earthquake-sustainable structural designs, and (3) extensive forestation for slope stability, erosion control, and provision of wood for flexible earthquake-resistant structures. The measures are needed for the sustainable development of the region.

Item Type: Article
Erschienen: 2015
Creators: Jadoon, I. A. K. and Hinderer, Matthias and Kausar, A. B. and Qureshi, A. A. and Baig, M. S. and Basharat, M. and Frisch, W.
Title: Structural Interpretation and Geo-Hazard Assessment of a Locking Line, 2005 Kashmir Earthquake, Western Himalayas.
Language: English
Abstract:

The 08 October 2005, magnitude (Mw) 06 Kashmir earthquake occurred along the Balakot–Bagh fault (BBF) with about 30° dip toward NE in the internal part of the western Himalayas in north Pakistan. It was accompanied by a ground rupture of about 75 km with an average slip of about 5 m along the causative fault. The epicenter of the thrust was located at about 19 km to the NE of its surface trace in Muzaffarabad with about 11 km depth of the hypocenter. The geometry of the fault based on a structural cross section has allowed us to interpret it as a thrust restricted to a roof sequence along a triangle zone across the Hazara–Kashmir syntaxis (HKS). The triangle zone is occupied at depth by a wedge of the Higher Himalayan Sequence (HHS) in the core zone of the HKS. The core–wedge is bounded between the NE-dipping BBF and SE- to SW-dipping thrust stack of the Lesser Himalayan Sequence (LHS) along the northeastern and southwestern limb of the HKS, respectively. Based on surface geology, the overlapping BBF and MBT are interpreted to merge at depth in a roof thrust of Pre-Cambrian (Late Proterozoic) rocks above a duplex which is inferred to have a floor thrust in Early Proterozoic/Archean rocks. The core–wedge is located over a ramp which is connected to the floor thrust in the basement. The BBF is inferred to be active, at least since 1–0.5 Ma, with recurrence interval of about 625 ± 125 years. This out-of-sequence deformation is represented by linear seismicity, both along emergent and blind thrusts in the system, with likelihood of major events as a result of strain buildup due to slow convergence rates (~7 mm/year) in the region. Many towns located along the active fault trace were destroyed or largely damaged due to the earthquake. Major destruction of human dwellings and infrastructure occurred as a consequence of earthquake-triggered landslides, mostly along fault, high river terraces, and road cuts. To minimize future damages in earthquake-prone areas, several mitigation measures are suggested including: (1) avoiding new settlements near the fault trace and landslide susceptible areas, (2) establishment of new township schemes in relatively safer areas with earthquake-sustainable structural designs, and (3) extensive forestation for slope stability, erosion control, and provision of wood for flexible earthquake-resistant structures. The measures are needed for the sustainable development of the region.

Journal or Publication Title: Environmental Earth Sciences
Volume: 73
Number: 11
Publisher: Springer Link Berlin Heidelberg 2012
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Earth Science
11 Department of Materials and Earth Sciences > Earth Science > Applied Sedimentary Geology
Date Deposited: 26 Jan 2016 18:20
Official URL: http://link.springer.com/article/10.1007/s12665-014-3929-7
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