Current Science

Open Access Open Access  Restricted Access Subscription Access

Insights into the Great Mw 7.9 Nepal Earthquake of 25 April 2015


Affiliations
1 Department of Applied Geophysics, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 007, India
2 Life, Environmental and Earth Sciences Division, University of Bucharest, Romania
 

The 2015 Mw 7.9 earthquake occurred in the Nepal Himalaya between the Indian and Asian plates. The gravity modelling has been carried out along a 2D trench-orthogonal profile passing through the epicentre of this earthquake. The projections of mainshocks and aftershocks show their major confinement around the bending segment of the Indian upper crust (IUC). The operative shallowly plunging maximum compressive stress led to the accumulation of strain energy around the bending zone of the IUC, and triggered thrust-dominated southward movement of the Indian crustal block along a shallowly, dipping shear plane in the anisotropic layer. This can be broadly explained by three-stage rupture processes: the first one was associated with slow nucleation and rupture growth for early ~15 sec, the second one migrated upward, rupturing the uppermost part of the IUC for the next ~10 sec, and the third one propagated very fast during deformation for the remaining ~25 sec till the fracture- tip reached the overlying brittle Asian crust.

Keywords

2015 Nepal Earthquake, Frictional Sliding, Gravity Modelling, Indian Upper Crust.
User
Notifications
Font Size

  • Ni, J. and Barazangi, M., Seismotectonics of the Himalayan collision zone: geometry of the underthrusting Indian Plate beneath the Himalaya. J. Geophys. Res., 1984, 89, 1147–1163.

  • Khan, P. K., Ansari, M. A. and Mohanty, S., Earthquake source characteristics along the arcuate Himalayan belt: geodynamic implications. J. Earth Syst. Sci., 2014, 123, 1013–1030.

  • Klootwijk, C. T., Conaghan, P. J. and Powell, C. M., The Himalayan arc: large-scale continental subduction, oroclinal bending, and back-arc spreading. Earth Planet. Sci. Lett., 1985, 75, 316–319.

  • Willet, S. D. and Beaumont, C., Subduction of Asian lithospheric mantle beneath Tibet inferred from models of continental collision. Nature, 1994, 369, 642–645.

  • Nabelek, J. et al., Underplating in the Himalaya-Tibet Collision Zone revealed by the Hi-CLIMB Experiment. Science, 2009, 325, 1371–1374.

  • Karner, G. D. and Watts, A. B., Gravity anomalies and flexure of the lithosphere at mountain ranges. J. Geophys. Res., 1983, 88(10), 449–477.

  • Lyon-Caen, H. and Molnar, P., Gravity anomalies, flexure of the Indian plate, and the structure, support and evolution of the Himalaya and Ganga Basin. Tectonics, 1985, 4, 513–538.

  • Jin, Y., McNutt, M. K. and Zhu, Y. S., Mapping the descent of Indian and Eurasian plates beneath the Tibetan Plateau from gravity anomalies. J. Geophys. Res., 1996, 101, 11275–11290.

  • Cattin, R., Martelet, G., Henry, P., Avouac, J. P., Diament, M. and Shakya, T. R., Gravity anomalies, crustal structure and thermomechanical support of the Himalaya of Central Nepal. Geophys. J. Int., 2001, 147, 381–392.

  • Hetényi, G., Cattin, R., Vergne, J. and Nábělek, J. L., The effective elastic thickness of the India Plate from receiver function imaging, gravity anomalies and thermomechanical modeling. Geophys. J. Int., 2006, 167, 1106–1118.

  • Tiwari, V. M., Vyghreswara, R., Mishra, D. C. and Singh, B. Crustal structure across Sikkim, NE Himalaya from new gravity and magnetic data. Earth Planet. Sci. Lett., 2006, 247, 61–69.

  • Bai, B., Zhang, S. and Braitenberg, C., Crustal density structure from 3D gravity modeling beneath Himalaya and Lhasa blocks, Tibet. J. Asian Earth Sci., 2013, 78, 301–317.

  • Ansari, M. A. and Khan, P. K., Occurrences of damaging earthquakes between the Himachal and Darjeeling Himalayas: tectonic implications. Acta Geophys., 2014, 62, 699–736.

  • Patriat, P. and Achache, J., India–Eurasia collision chronology has implications for crustal shortening and driving mechanism for plates. Nature, 1984, 311, 615–621.

  • Gaetani, M. and Garzanti, E., Multicyclic history of the northern India continental margin (northwestern Himalaya). Bull. Am. Assoc. Pet. Geol., 1991, 75, 1427–1446.

  • de Sigoyer, J. et al., Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: multichronology of the Tso Morari eclogites. Geology, 2000, 28, 487–490.

  • Guillot, S., Garzanti, E., Baratoux, D., Marquer, D., Mahe´o, G. and de Sigoyer, J., Reconstructing the total shortening history of the NW Himalaya. Geochem. Geophys. Geosyst., 2003, 4(7), 1064.

  • Aikman, A. B., Harrison, T. M. and Lin, D., Evidence for Early (>44 Ma) Himalayan crustal thickening, Tethyan Himalaya, southeastern Tibet. Earth Planet. Science Lett., 2008, 274, 14–23.

  • Copley, A., Avouac, J. P. and Royer, J. Y., India–Asia collision and the Cenozoic slowdown of the Indian plate: implications for the forces driving plate motions. J. Geophys. Res., 2010, 115, B03410 (1–14).

  • Le Fort, P., Metamorphism and magmatism during the Himalayan collision. In Collision Tectonics (eds Coward, M. P. and Ries, A. C.), Geological Society of London, Special Publication, 1986, vol. 19, pp. 159–172.

  • Lave, J. and Avouac, J. P., Active folding of fluvial terraces across the Siwaliks Hills, Himalayas of central Nepal. J. Geophys. Res., 2000, 105, 5735–5770.

  • Schulte-Pelkum, V., Monsalve, G., Sheehan, A., Pandey, M. R., Sapkota, S., Bilham, R. and Wu, F., Imaging the Indian subcontinent beneath the Himalaya. Nature, 2005, 435, 1222–1225.

  • Srivastava, P. and Mitra, G., Thrust geometries and deep structure of the outer and lesser Himalaya, Kumaon and Garhwal (India): implications for evolution of the Himalayan fold-and-thrust belt. Tectonics, 1994, 13, 89–109.

  • Makovsky, Y., Klemperer, S. L., Huang, L. and Project INDEPTH Team, Structural elements of the southern Tethyan Himalaya crust from wide-angle seismic data. Tectonics, 1996, 15, 997–1005.

  • Nelson, K. D. et al., Partially molten middle crust beneath southern Tibet: synthesis of project INDEPTH results. Science, 1996, 274, 1684–1688.

  • DeCelles, P. G., Gehrels, G. E., Quade, J. and Ojha, T. P., Eocene–early Miocene foreland basin development and the history of Himalayan thrusting, western and central Nepal. Tectonics, 1998, 17, 741–765.

  • Hauck, M. L., Nelson, K. D., Brown, L. D., Zhao, W. and Ross, A. R., Crustal structure of the Himalaya orogen at ~90° east longitude from INDEPTH deep reflection profiles. Tectonics, 1998, 17, 481–500.

  • Mukul, M., The geometry and kinematics of the Main Boundary Thrust and related neotectonics in the Darjiling Himalayan foldandthrust belt, West Bengal, India. J. Struct. Geol., 2000, 22, 1261–1283.

  • Bollinger, L., Henry, P. and Avouac, J. P., Mountain building in the Nepal Himalaya: thermal and kinematic model. Earth Planet. Sci. Lett., 2006, 244, 58–71.

  • Mukul, M., Jaiswal, M. and Singhvi, A. K., Timing of recent outofsequence active deformation in the frontal Himalayan wedge: insights from the Darjiling sub-Himalaya, India. Geology, 2007, 35, 999–1002.

  • Mukul, M., First-order kinematics of wedge-scale active Himalayan deformation: insights from Darjiling–Sikkim–Tibet (DaSiT) wedge. J. Asian Earth Sci., 2010, 39, 645–657.

  • DeMets, C., Gordon, R. G., Argus, D. F. and Stein, S., Effect of recent revisions to the geomagnetic reversal time scale and estimates of current plate motions. Geophys. Res. Lett., 1994, 21, 2191–2194.

  • Larson, K. M., Bürgmann, R., Bilham, R. and Freymuelle, J. T., Kinematics of the India–Eurasia collision zone from GPS measurements. J. Geophys. Res., 1999, 104, 1077–1093.

  • Bettinelli, P., Avouac, J.-P., Flouzat, M., Jouanne, F., Bollinger, L., Willis, P. and Chitrakar, G. R., Plate motion of India and interseismic strain in the Nepal Himalaya from GPS and DORIS measurements. J. Geodesy., 2006, 80, 567–589.

  • Lyon-Caen, H. and Molnar, P., Constraints on the structure of the Himalaya from an analysis of gravity anomalies and a flexural model of the lithosphere. J. Geophys. Res., 1983, 88, 8171–8192.

  • Artyushkov, E. V., Stresses in the lithosphere caused by crustal thickness inhomogeneities. J. Geophys. Res., 1973, 78, 7675–7708.

  • Molnar, P. and Lyon-Caen, H., Some simple physical aspects of the support, structure, and evolution of mountain belts. Geol. Soc. Am. Spec. Pap., 1988, 218, 179–208.

  • Hirn, A., Jobert, G., Wittlinger, G., Zhong-Xin, X. and En-Yuan, G., Main features of the upper lithosphere in the unit between the High Himalayas and the Yarlung Angbo Jiang suture. Ann. Geophys., 1984, 2, 113–118.

  • McKenzie, D. and Fairhead, D., Estimates of effective elastic thickness of the continental lithosphere from Bouguer and gravity anomalies. J. Geophys. Res., 1997, 102, 27523–27552.

  • Watts, A. B. and Burov, E. B., Lithospheric strength and its relationship to the elastic and seismogenic layer thickness. Earth Planet. Sci. Lett., 2003, 213, 113–131.

  • Bapat, A., Kulkarni, R. C. and Guha, S. K., Catalogue of earthquakes in India and neighborhood – from historical period up to 1979. Indian Society of Earthquake Technology, Roorkee, 1983, p. 211.

  • Avouac, J.-P., Meng, L., Wei, S., Wang, T. and Ampuero, J.-P., Unzipping lower edge of locked Main Himalayan thrust during the 2015, Mw 7.8 Gorkha earthquake. Nature Geosci., 2015, 8, 708–711.

  • Grandin, R., Vallée, M., Satriano, C., Lacassin, R., Klinger, Y., Simoes, M. and Bollinger, L., Rupture process of the Mw = 7.9 2015 Gorkha earthquake (Nepal): Insights into Himalayan megathrust segmentation. Geophys. Res. Lett., 2015, 42, 8373–8382.

  • He, X., Ni, S., Ye, L., Lay, T., Liu, Q. and Koper, K. D., Rapid seismological quantification of source parameters of the 25 April 2015 Nepal earthquake. Seismol. Res. Lett., 2015, 86, 1568–1577.

  • Wu, Y. et al., Coseismic deformations of the 2015 Mw 7.8 Gorkha earthquake and interseismic strain accumulation in the Himalayan tectonic belt and Tibetan plateau. Tectonophysics, 2016, 670, 144–154.

  • Galetzka, J. et al., Slip pulse and resonance of the Kathmandu basin during the 2015 Gorkha earthquake, Nepal. Science, 2015, 349, 1091–1095.

  • Zhang, G., Hetland, E. and Shan, X., Slip in the 2015 Mw 7.9 Gorkha and Mw 7.3 Kodari, Nepal, earthquakes revealed by seismic and geodetic data: delayed slip in the Gorkha and slip deficit between the two earthquakes. Seismol. Res. Lett., 2015, 86, 1578–1586.

  • DMG, Exploration opportunities in Nepal. Department of Mines and Geology, Kathmandu, 1990, p. 32.

  • Brown, L. D. et al., Bright spots, structure, and magmatism in southern Tibet from INDEPTH seismic reflection profiling. Science, 1996, 274, 1688–1690.

  • Lemonnier, C. et al., Electrical structure of the Himalaya of Central Nepal: high conductivity around the mid-crustal ramp along the MHT. Geophys. Res. Lett., 1999, 26, 3261–3264.

  • Gansser, A., The geodynamic history of the Himalaya. In Zagros, Hindu-Kush, Himalaya. Geodynamic Evolution (eds Gupta, H. K. and Delany, F. M.), American Geophysical Union, Geodynamics Series 3, Washington, DC, USA, 1981, pp. 111–121.

  • Jimenez-Munt, I., Fernandez, M., Jaume, V. and John, P. P., Lithosphere structure underneath the Tibetan Plateau inferred from elevation, gravity and geoid anomalies. Earth Planet. Sci. Lett., 2008, 267, 276–289.

  • Hetenyi, G., Cattin, R., Brunet, F., Bollinger, L., Vergne, J., Nabelek, J. L. and Diament, M., Density distribution of the India plate beneath the Tibetan plateau: Geophysical and petrological constraints on the kinetics of lower-crustal eclogitization. Earth Planet. Sci. Lett., 2007, 264, 226–244.

  • Hough, S. E., Introduction to the Focus Section on the 2015 Gorkha, Nepal, earthquake. Seismol. Res. Lett., 2015, 86, 1502–1505.

  • Hayes, G. P. et al., Rapid characterization of the 2015 Mw 7.8 Gorkha, Nepal, earthquake sequence and its seismotectonic context. Seismol. Res. Lett., 2015, 86, 1557–1567.

  • Kelleher, J. and McCann, W., Buoyant zones, great earthquakes, and unstable boundaries of subduction. J. Geophys. Res., 1976, 81, 4885-4898.

  • McGeary, S., Nur, A. and Ben-Avraham, Z., Spatial gaps in arc volcanism: the effect of collision or subduction of oceanic plateaus. Tectonophysics, 1985, 119, 195–221.

  • Gutscher, M.-A., Malavieille, J., Lallemand, S. and Collot, J.-Y., Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision. Earth Planet. Sci. Lett., 1999, 168, 255–270.

  • Khan, P. K. and Chakraborty, P. P., Two-phase opening of Andaman Sea: a new seismotectonic insight. Earth Planet. Sci. Lett., 2005, 229, 259–271.

  • Gutenberg, B. and Richter, C. F., Seismicity of the Earth and Associated Phenomenon, Princeton University Press, Princeton, NJ, USA, 1954.

  • Khan, P. K. and Chakraborty, P. P., The seismic b value and its correlation with Bouguer gravity anomaly over the Shillong plateau area: a new insight for tectonic implication. J. Asian Earth Sci., 2007, 29, 136–147.

  • Khan, P. K., Ghosh, M., Chakraborty, P. P. and Mukherjee, D., Seismic b-value and the assessment of ambient stress in Northeast India. Pure Appl. Geophys., 2011, 168, 1693–1706.

  • Pandey, M. R., Tandukar, R. P., Avouac, J. P., Vergne, J. and Héritier, Th., Seismotectonics of the Nepal Himalaya from a local seismic network. J. Asian Earth Sci., 1999, 17, 703–712.

  • Conrad, C. P. and Hager, B. H., Effects of plate bending and fault strength at subduction zones on plate dynamics. J. Geophys. Res., 1999, 104, 17551–17571.

  • Turcotte, D. L. and Schubert, G., Geodynamics Applications of Continuum Physics to Geological Problems, Wiley, New York, USA, 1982, p. 450.

  • Singh, S. C. et al., Seismic evidence for broken oceanic crust in the 2004 Sumatra earthquake epicentral region. Nature Geosci., 2008, 1, 777–781.

  • Khan, P. K. and Chakraborty, P. P., Bearing of plate geometry and rheology on shallow-focus mega-thrust seismicity with special reference to 26 December 2004 Sumatra event. J. Asian Earth Sci., 2009, 34, 480–491.

  • Khan, P. K., Chakraborty, P. P., Tarafder, G. and Mohanty, S., Testing the intraplate origin of mega-earthquakes at subduction margins. Geosci. Front., 2012, 3, 473–481.

  • Satriano, C., Analysis fact sheet, 2015; http://www.ipgp.fr/en/central-nepal-earthquake-april-25th-2015

  • Bilham, R., Larson, K. and Freymüller, J., GPS measurements of present-day convergence across the Nepal Himalaya. Nature, 1997, 386, 61–64.

  • Lyakhovsky, V., Scaling of fracture length and distributed damage. Geophys. J. Int., 2001, 144, 114–122.

  • Wang, D. and Mori, J., Short-period energy of the 25 April 2015 Mw 7.8 Nepal earthquake determined from backprojection using four arrays in Europe, China, Japan, and Australia. Bull. Seismol. Soc. Am., 2016, 106, 259–266.

  • Mitra, S., Paul, H., Kumar, A., Singh, S. K., Dey, S. and Powali, D., The 25 April 2015 Nepal earthquake and its aftershocks. Curr. Sci., 2015, 108, 1938–1943.

  • Reber, J. E., Lavier, L. L. and Hayman, N. W., Experimental demonstration of a semi-brittle origin for crustal strain transients. Nature Geosci., 2015, 8, 712–715.


Abstract Views: 232

PDF Views: 84




  • Insights into the Great Mw 7.9 Nepal Earthquake of 25 April 2015

Abstract Views: 232  |  PDF Views: 84

Authors

Prosanta Kumar Khan
Department of Applied Geophysics, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 007, India
Md. Afroz Ansari
Life, Environmental and Earth Sciences Division, University of Bucharest, Romania
Dhananjay Singh
Department of Applied Geophysics, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 007, India

Abstract


The 2015 Mw 7.9 earthquake occurred in the Nepal Himalaya between the Indian and Asian plates. The gravity modelling has been carried out along a 2D trench-orthogonal profile passing through the epicentre of this earthquake. The projections of mainshocks and aftershocks show their major confinement around the bending segment of the Indian upper crust (IUC). The operative shallowly plunging maximum compressive stress led to the accumulation of strain energy around the bending zone of the IUC, and triggered thrust-dominated southward movement of the Indian crustal block along a shallowly, dipping shear plane in the anisotropic layer. This can be broadly explained by three-stage rupture processes: the first one was associated with slow nucleation and rupture growth for early ~15 sec, the second one migrated upward, rupturing the uppermost part of the IUC for the next ~10 sec, and the third one propagated very fast during deformation for the remaining ~25 sec till the fracture- tip reached the overlying brittle Asian crust.

Keywords


2015 Nepal Earthquake, Frictional Sliding, Gravity Modelling, Indian Upper Crust.

References





DOI: https://doi.org/10.18520/cs%2Fv113%2Fi10%2F2014-2020