Abstract
The present study produces very new SKKS splitting measurements from the Northeast India, suggesting the region as tectonically more heterogeneous and complex in nature. It fills the gap of anisotropic parameters from an epicentral range of 140°–180° in order to understand the lithospheric deformation patterns of the terrain in a better way. The splitting parameters namely polarisation direction of fast waves (ϕ) and delay time are the manifestation of anisotropic effects of a medium. The present SKKS splitting measurements from nine broadband seismic stations in Northeast India incorporate new understandings of deformation patterns for this region. At the Himalayan collision zone and sub-Himalayan region, the deformation pattern showing a perfect alignment of the ϕ parallel to the collisional arc (Main Boundary Thrust, Main Central Thrust), suggests that a localized strain derived from N-S Indo-Eurasian collision is the major source behind its complex tectonics. The SKKS splitting measurements at Assam foredeep region streamline the effect of Kopili fault in controlling the deformation patterns in a NW-SE direction. There is a significant difference in anisotropic behaviour of stations at the northern Shillong plateau compared to the stations at its southern proximity. The absolute plate motion (APM) parallel to ϕ in northern fringe of the plateau strictly indicates the influence of asthenospheric flow, which in turn is driven by APM of Indian plate in a no net rotation reference frame. On the other hand, major regional structures like the Dauki and Dapsi faults control the anisotropic pattern at the southern extremity of this plateau.
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References
Angelier J. and Baruah S., 2009. Seismotectonics in Northeast India: a stress analysis of focal mechanism solutions of earthquakes and its kinematic implications. Geophys. J. Int., 178, 303–326, DOI: https://doi.org/10.1111/j.1365-246X.2009.04107.x
Barruol G., Silver P. and Vauchez A., 1997. Seismic anisotropy in the eastern United States: deep structure of a complex continental plate. J. Geophys. Res., 102(B4), 8329–8348, DOI: https://doi.org/10.1029/96JB03800
Bilham R. and England P., 2001. Plateau “pop-up” in the great 1897 Assam earthquake. Nature, 410, 806–809, DOI: https://doi.org/10.1038/35071057
Bowman J. and Ando M., 1987. Shear-wave splitting in the upper mantle wedge above the Tonga subduction zone. Geophys. J. Int., 88, 25–41, DOI: https://doi.org/10.1111/j.1365-246X.1987.tb01367.x
Christensen N.I. and Crosson R.S., 1968. Seismic anisotropy in the upper mantle. Tectonophysics, 6, 93–107, DOI: https://doi.org/10.1016/0040-1951(68)90013-9
DeMets C., Gordon R., Argus D. and Stein S., 1994. Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions. Geophys. Res. Lett., 21, 2191–2194, DOI: https://doi.org/10.1029/94GL02118
Hazarika D., Yadav D., Sriram V. and Rai A., 2013. Upper mantle anisotropy beneath northeast India-Asia collision zone from shear wave splitting analysis. Int. J. Earth Sci., 102, 2061–2076, DOI: https://doi.org/10.1007/s00531-013-0922-4
James D.E. and Assumpção M., 1996. Tectonic implications of S-wave anisotropy beneath SE Brazil. Geophys. J. Int., 126, 1–10, DOI: https://doi.org/10.1111/j.1365-246X.1996.tb05263.x
Kayal J.R., Arefiev S., Baruah S., Hazarika D., Gogoi N., Gautam J.L., Baruah S., Dorbath C. and Tatevossian R., 2012. Large and great earthquakes in the Shillong plateau — Assam valley area of Northeast India region: pop-up and transverse tectonics. Tectonophysics, 532–535, 186–192, DOI: https://doi.org/10.1016/j.tecto.2012.02.007
Kayal J.R., 2010. Himalayan tectonic model and the great earthquakes: an appraisal. Geomat. Nat. Hazards Risk, 1, 51–67, DOI: https://doi.org/10.1080/19475701003625752
Kayal J.R. and De R., 1991. Microseismicity and tectonics in northeast India. Bull. Seismol. Soc. Amer., 81, 131–138
Kendall J. and Silver P., 1996. Constraints from seismic anisotropy on the nature of the lowermost mantle. Nature, 381, 409–412, DOI: https://doi.org/10.1038/381409a0
Khattri K., Wyss M., Gaur V.K., Saha S.N. and Bansal V.K., 1983. Local seismic activity in the region of the Assam Gap, northeast India. Bull. Seismol. Soc. Amer., 73, 459–469
Lei W. and Lianxing W., 2020. Widespread small-scale anisotropic structure in the lowermost mantle beneath the North American continent and Northeastern Pacific. Seismol. Res. Lett., 91, 2779–2790, DOI: https://doi.org/10.1785/0220200055
Mohanty D.D. and Mondal P., 2020. Disparate behaviour of deformation patterns beneath northeast Indian lithosphere inferred from shear wave splitting analysis. Phys. Earth Planet. Inter., 298, Art.No. 106315, DOI: https://doi.org/10.1016/j.pepi.2019.106315
Mohanty D.D., Singh A., O’Driscoll L.J., Ravi Kumar M., Srinagesh D. and Humphreys E.D., 2016. P wave velocity structure below India and Tibet incorporating anisotropic delaytime effects. Geochem. Geophys. Geosyst., 17, 25–738, DOI: https://doi.org/10.1002/2015GC006064
Nandy D., 2001. Geodynamics of Northeastern India and the Adjoining Region. 1st Edition. ACB Publications, Kolkata, India
Nandy D. and Dasgupta S., 1986. Application of remote sensing in regional geological studies — a case study in the northeastern part of India. In: Sharma L.P. (Ed.), International Seminar on Photogrammetry and Remote Sensing for Developing Countries: Proceedings, 1, 106–111, Government of India, New Delhi, India
Nicolas A. and Christensen N., 1987. Formation of anisotropy in upper mantle peridotites: a review. In: Fuchs K. and Froideveaux C. (Eds), Composition, Structure and Dynamics of the Lithosphere Asthenosphere System. American Geophysical Union, Washington, D.C., 111–123
Niu F. and Perez A., 2004. Seismic anisotropy in the lower mantle: A comparison of waveform splitting of SKS and SKKS. Geophys. Res. Lett., 31, L24612, DOI: https://doi.org/10.1029/2004GL021196
Oldham R.D., 1899. Report on the great earthquake of the 12th June 1897. Geol. Surv. India Mem., 29, 1–379
Restivo A. and Helffrich G., 2006. Core-mantle boundary structure investigated using SKS and SKKS polarization anomalies. Geophys. J. Int., 165, 288–302, DOI: https://doi.org/10.1111/j.1365-246X.2006.02901.x
Roy S., Kumar M. and Srinagesh D., 2014. Upper and lower mantle anisotropy inferred from comprehensive SKS and SKKS splitting measurements from India. Earth. Planet. Sci. Lett., 392, 192–206, DOI: https://doi.org/10.1016/j.epsl.2014.02.012
Saikia D., Kumar M., Singh A., Mohan G. and Dattatrayam R., 2010. Seismic anisotropy beneath the Indian continent from splitting of direct S waves. J. Geophys. Res.-Solid Earth, 115, B12315, DOI: https://doi.org/10.1029/2009JB007009
Saltzer R., Gaherty J. and Jordan T., 2000. How are vertical shear wave splitting measurements affected by variations in the orientation of azimuthal anisotropy with depth? Geophys. J. Int., 141, 374–390, DOI: https://doi.org/10.1046/j.1365-246x.2000.00088.x
Savage M.K., 1999. Seismic anisotropy and mantle deformation: what have we learned from shear wave splitting? Rev. Geophys., 37, 65–106, DOI: https://doi.org/10.1029/98RG02075
Silver P.G., 1996. Seismic anisotropy beneath the continents:probing the depths of geology. Annu. Rev. Earth Planet. Sci., 24, 385–432. DOI: https://doi.org/10.1146/annurev.earth.24.1.385
Silver P.G. and Chan W., 1991. Shear wave splitting and subcontinental mantle deformation. J. Geophys. Res.-Solid Earth, 96, 16429–16454, DOI: https://doi.org/10.1029/91JB00899
Singh A., Kumar M.R., Raju P.S. and Ramesh D., 2006. Shear wave anisotropy of the northeast Indian lithosphere. Geophys. Res. Lett., 33, L16302, DOI: https://doi.org/10.1029/2006GL026106
Vanacore E. and Niu F., 2011. Characterization of the D″ beneath the Galapagos Islands using SKKS and SKS waveforms. Earthq. Sci., 24, 87–99, DOI: https://doi.org/10.1007/s11589-011-0772-8
Wüstefeld A. and Bokelmann G., 2007. Null detection in shear-wave splitting measurements. Bull. Seismol. Soc. Amer., 97, 1204–1211, DOI: https://doi.org/10.1785/0120060190
Wüstefeld A., Bokelmann G., Zaroli C. and Barruol G., 2008. SplitLab: A shear-wave splitting environment in Matlab. Comput. Geosci., 34, 515–528, DOI: https://doi.org/10.1016/j.cageo.2007.08.002
Yadav R. and Tiwari V., 2018. Numerical simulation of present day tectonic stress across the Indian subcontinent. Int. J. Earth Sci., 107, 2449–2462, DOI: https://doi.org/10.1007/s00531-018-1607-9
Acknowledgements
DDM acknowledges the permission and support provided by Director, CSIR-NEIST, for utilization of data in research work and its publication (NMN-202022). The authors are also thankful to National Geophysical Research Institute (NGRI), Hyderabad and Ministry of Earth Sciences (MoES) for providing seismological data. The study is supported by Early Career Research Grant from Science and Engineering Research Board (SERB), India (Grant No. ECR/2018/001293). PM acknowledges the Department of Science and Technology (DST) for fellowship grant (Inspire Fellowship No. IF180255) and Academy of Scientific and Innovative Research (AcSIR) for academic support.
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Mondal, P., Mohanty, D.D. Mantle deformation and seismic anisotropy beneath Northeast India inferred from SKKS birefringence. Stud Geophys Geod 65, 36–52 (2021). https://doi.org/10.1007/s11200-020-1121-y
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DOI: https://doi.org/10.1007/s11200-020-1121-y