Evidence, of paleoearthquakes from trench investigations across Pinjore Garden fault in Pinjore Dun, NW Himalaya
DSpace at IIT Bombay
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Title |
Evidence, of paleoearthquakes from trench investigations across Pinjore Garden fault in Pinjore Dun, NW Himalaya
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Creator |
MALIK, JN
MATHEW, G |
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Subject |
plate-boundary
earthquake kinematics geometry thrust deformation hazard india pinjore himalaya active faults paleoearthquakes trench |
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Description |
The Pinjore Garden Fault (PGF) striking NNW-SSE is now considered one of the active faults displacing the younger Quaternary surfaces in the piggyback basin of Pinjore Dun: This has displaced the older Kalka and Pinjore surfaces, along with the other younger surfaces giving rise to WSW and SW-facing fault scarps with heights ranging from 2 to 16m. The PGF represents a younger branch of the Main Boundary Thrust (MBT) system. An similar to 4m wide trench excavated across the PGF has revealed displacement of younger Quaternary deposits along a low angle thrust fault. Either side of the trench-walls reveals contrasting slip-related deformation of lithounits. The northern wall shows displacement of lithounits along a low-angle thrust fault, while the southern wall shows well-developed fault-related folding of thick sand unit. The sudden change in the deformational features on the southern wall is an evidence of the changing fault geometry within a short distance. Out of five prominent lithounits identified in the trench, the lower four units show displacement along a single fault. The basal unit 'A' shows maximum displacement of about T-o = 2.85 m, unit B = 1.8 m and unit C = 1.45 m. The displacement measured between the sedimentary units and retro-deformation of trench log suggests that at least two earthquake events have occurred along the PGF. The units A and D mark the event horizons. Considering the average amount of displacement during one single event (2m) and the minimum length of the fault trace (similar to 45 km), the behaviour of PGF seems similar to that of the Himalayan Frontal Fault (HFF) and appears capable of producing large magnitude earthquakes.
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Publisher |
INDIAN ACADEMY SCIENCES
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Date |
2011-08-02T03:30:50Z
2011-12-26T12:53:40Z 2011-12-27T05:40:25Z 2011-08-02T03:30:50Z 2011-12-26T12:53:40Z 2011-12-27T05:40:25Z 2005 |
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Type |
Article
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Identifier |
JOURNAL OF EARTH SYSTEM SCIENCE, 114(4), 387-400
0253-4126 http://dx.doi.org/10.1007/BF02702139 http://dspace.library.iitb.ac.in/xmlui/handle/10054/8640 http://hdl.handle.net/10054/8640 |
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Language |
en
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