Damage Survey Report for Sikkim Earthquake of 18 September 2011

Sharma, M. L.; Sinvhal, Amita; Singh, Yogendra; Maheshwari, B. K.

doi:10.1785/0220120013

Cited by 18 publications

(17 citation statements)

References 4 publications

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“…Since then, it has been a topic of continuous study by the Geological Survey of India as well as academic researchers (see for example, Ray, ; Ghosh, ; Acharya, ; Acharya & Ray, ; Ghosh & Singh, ; Gangopadhyay, ; Sinha‐Roy, ) which have attempted to clarify the stratigraphic and structural relationships in the area. Interest in the structural, petrological, geophysical and geochronological evolution of the Sikkim Himalaya continues to the present day with an increase in the number of publications in the last few years ( Structure and regional patterns : Mukul, ; Searle & Szulc, ; Bhattacharyya & Mitra, , ; Matin & Mazumdar, ; Mitra et al ., ; Bose et al ., ; Bhattacharyya et al ., ,b; Bhattacharyya & Ahmed, ; Geophysics: Kayal, ; De & Kayal, ; Nath, ; Tiwari et al ., ; Singh et al ., ; Patro & Harinarayana, ; Hazarika et al ., ; Acton et al ., ; Mukhopadhyay, ; Hazarika et al ., ; Sharma et al ., ; Petrology and Geochemistry, including isotopic dating and thermochronometry: Banerjee & Bhattacharya, ; Lal et al ., ; Mohan et al ., ; Neogi et al ., ; Ganguly et al ., ; Chakraborty et al ., ; Catlos et al ., ; Dasgupta et al ., , ; Harris et al ., ; Dubey et al ., ; Chakraborty et al ., ; Gupta et al ., ; Faak et al ., ; Kellett et al ., ; Rubatto et al ., ; Anczkiewicz et al ., ; Mottram et al ., ,b, ,b; Neogi et al ., ; Sorcar et al ., ; Gaidies et al ., ; Landry et al ., ). We have used the references cited above, data from the reports of the Geological Survey of India (Chakrabarti et al ., ; Chakrabarti & Banerjee,…”

Section: General Geological Featuresmentioning

confidence: 99%

A review of thermal history and timescales of tectonometamorphic processes in Sikkim Himalaya (NE India) and implications for rates of metamorphic processes

Chakraborty

Anczkiewicz

Gaidies

et al. 2016

Journal Metamorphic Geology

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The lesser and greater Himalayan sequences (LH and GH) in Sikkim have been studied in detail recently. The LH consists mainly of pelitic lithologies with detrital zircon ages >1800 Ma and e Nd (0) of À27.7 to À23.4 (with intercalated calcsilicates, metabasites and a sheared granite gneiss -the Lingtse gneiss). The metamorphic sequence is characterized by (i) a remarkably continuous and systematic metamorphic field gradient (~60-70°C kbar À1 ), (ii) peak pressures as well as temperatures of metamorphism increasing at higher metamorphic grades (~5 kbar, 500°C at the garnet zone tõ 8 kbar, 700°C at the sillimanite-muscovite-zone), (iii) clockwise P-T paths of a tight 'hairpin' shape with a prograde slope of 20-30°C kbar À1 , (iv) initiation of garnet growth (Lu-Hf chronometry) at systematically older ages at higher grades (11-10.5 Ma at garnet zone to 16.8 Ma at sillimanite-K-feldspar zone), (v) peak of metamorphism simultaneously at all grades (13-11 Ma), (vi) deformed and folded metapelitic rocks but with little evidence of pervasive shearing and (vii) duration of melt formation and segregation on the order of a few 100,000 years. The degree of melting was low, as indicated by the presence of muscovite all through the sequence. This evidence indicates that the LH behaved as a coherent block, and thermomechanical models quantitatively reproduce many of these features as well as explain the formation of inverted metamorphic sequence in such a coherent block. The greater Himalayan sequence (GH), also largely metapelitic, has different protoliths (with components as young as 800 Ma) and a different metamorphic history (extensive migmatization at higher grades~8-12 kbar, 750-850°C at an older age of largely >20 Ma along a different clockwise P-T path characterized by sharp, isothermal decompression followed by near isobaric cooling). Geochronological data (monazite, zircon, garnet) as well as cooling rate calculations (geospeedometry) reveal that the GH is made up of at least two blocks with distinct, complex and multistage P-T-t histories. Different stages of the high-T cooling were rapid (100's°C Ma À1 to 10's°C Ma À1 at different stages) and at least some of it was unrelated to exhumation; synthesis of these results with low-T thermochronometry allows the detailed multistage cooling and exhumation history of this block to be reconstructed. The reconstructed cooling and exhumation histories show that a number of interlinked processes operating on a hierarchy of timescales leads to the overall evolution. The P-T history with rapid cooling can be reproduced by thermomechanical models that consider conductive as well as advective heat transport and there is no need to invoke additional processes (such as the role of fluids). Metabasic inclusions within both the LH and the GH appear to record a different (? older in part) history. The role of these in the overall evolution, as well as the difference in metamorphic ages of the LH and GH remain open questions that need to be addressed in future research.

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Section: General Geological Featuresmentioning

confidence: 99%

A review of thermal history and timescales of tectonometamorphic processes in Sikkim Himalaya (NE India) and implications for rates of metamorphic processes

Chakraborty

Anczkiewicz

Gaidies

et al. 2016

Journal Metamorphic Geology

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“…It has been observed that under the action of moderate to severe earthquake occurrences (e.g. Bihar 1988 [1], Garhwal 1991 [2], Killari 1993 [3], Jabalpur 1997 [4], Chamoli 1999 [5], Bhuj 2001 [6], Sumatra 2004 [7], Jammu and Kashmir 2005 [8], Sikkim 2006 and 2011 [9], [10], Nepal 2015 [11]), the masonry buildings performed the worst, causing the largest loss of lives as well as the properties of the residents. Thus in order to save the life of people from collapse of such buildings during earthquake it is required to make them earthquake resistant.…”

Section: A Importance Of Workmentioning

confidence: 99%

Pushover Analysis for Seismic Evaluation of Masonry Wall

Sharma¹,

Khare²

2016

IJSCER

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The present work investigates the seismic evaluation of unreinforced masonry (URM) walls when subjected to seismic (lateral) loading. The work consists of modeling the geometry and property of masonry wall. After which non-linear analysis was performed using SAP 2000 software. The paper is divided in to two parts. One part reveals the size of finite element meshing suitable for modeling a unreinforced masonry wall in SAP 2000 software. While the other part investigates the result of nonlinear static analysis performed on selected model.

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“…The seismic Zone IV is broadly associated with seismic intensity VIII on the Modified Mercalli Intensity (MMI) scale. Earthquakes in this region are broadly associated with strain accumulation associated with the northward tectonic movement of the Indian plate and its subsequent abrupt release (Sharma et al 2013). The 18 September 2011 Sikkim earthquake is located NE to the junction of Kanchenjunga and Tista lineament.…”

Section: Seismotectonics Of Sikkim Himalayamentioning

confidence: 99%

“…According to Thakur et al (2012), as the strike-slip fault environment of 2011 Sikkim earthquake at the lower crust is something different to the seismogenic settings of north-western Himalaya and Nepal, there may be some transcurrent deformation at deeper depth in the region. Joshi et al (2012) have presented a rupture model using simulation of near-field and far-field accelerograms for this earthquake, while Sharma et al (2013) have prepared the isoseismal maps of the 18 September 2011 earthquake using the intensities assigned to various places in Sikkim and contiguous places. The isoseimlas are found to be of elliptical shape with its major axis in the NE-SW direction and minor axis in the NW-SE direction.…”

Section: Introductionmentioning

confidence: 99%

The September 2011 Sikkim Himalaya earthquake Mw 6.9: is it a plane of detachment earthquake?

Baruah

Saikia

Baruah

et al. 2014

Geomatics, Natural Hazards and Risk

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The 18 September 2011 Sikkim Himalaya earthquake of Mw 6.9 (focal depth 50 km, NEIC report) with maximum intensity of VII on MM scale (www.usgs. gov) occurred in the Himalayan seismic belt (HSB), to the north of the main central thrust. Neither this thrust nor the plane of detachment envisaged in the HSB model, however, caused this strong devastating earthquake. The EngdahlHilst-Buland (EHB) relocated past earthquakes recorded during 1965-2007 and the available global centroid moment tensor) solutions are critically examined to identify the source zone and stress regime of the September 2011 earthquake. The depth section plot of these earthquakes shows that a deeper (10-50 km) vertical fault zone caused the main shock in the Sikkim Himalaya. The NW (North-West) and NE (North-East) trending transverse fault zones cutting across the eastern Himalaya are the source zones of the earthquakes. Stress inversion shows that the region is dominated by horizontal NNW-SSE (North of North-West-South of South-East) compressional stress and low angle or near horizontal ENE-WSW (East of North-East-West of South-West) tensional stress; this stress regime is conducive for strike-slip faulting earthquakes in Sikkim Himalaya and its vicinity. The Coulomb stress transfer analysis indicates positive values of Coulomb stress change DS f for failure in the intersecting deeper fault zone that produced the four immediate felt aftershocks (M ! 4.0).

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Damage Survey Report for Sikkim Earthquake of 18 September 2011

Cited by 18 publications

References 4 publications

A review of thermal history and timescales of tectonometamorphic processes in Sikkim Himalaya (NE India) and implications for rates of metamorphic processes

A review of thermal history and timescales of tectonometamorphic processes in Sikkim Himalaya (NE India) and implications for rates of metamorphic processes

Pushover Analysis for Seismic Evaluation of Masonry Wall

The September 2011 Sikkim Himalaya earthquake Mw 6.9: is it a plane of detachment earthquake?

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