Collaborating scientists in the U.S. include research groups led by Dr. Marianne Karplus and Dr. Aaron Velasco at University of Texas at El Paso, Dr. John Nabelek at Oregon State Unviersity, Dr. Abhijit Ghosh at the University of California at Riverside, and Dr. Simon Klemperer at Stanford University. Collaborators in Nepal include Dr. Soma Nath Sapkota and Dr. Lok Bijaya Adhikari at the Department of Mines and Geology. We especially thank our collaborators in Nepal and all of the students and researchers who were involved in our seismic field work.
NAMASTE Project: Studying aftershocks of the 4/25/15 M7.8 Gorkha earthquake
The Nepal Array Measuring Aftershock Seismicity Trailing Earthquake (NAMASTE) is a 3-year collaborative research project supported by the U.S. National Science Foundation to study the tectonic setting and rupture process of large earthquakes in the Himalaya, with focus of the 4/25/15 Gorkha M=7.8 earthquake. The Gorkha earthquake is the largest to occur in the central segment of the Himalaya in 80 years. Gaining a better understanding of the tectonic setting and rupture process of these large earthquakes will both illuminate the processes causing large Himalayan earthquakes as well as large subduction zone earthquakes. We are studying the geometry of faults (including the Main Himalayan Thrust), composition of the crust and upper mantle, rupture process, and broader geotectonic setting in the Himalaya and southern Tibet.
To study these processes, we will use ground motion recordings from a seismic array of 45 seismic stations across eastern and central Nepal, spanning the region with most of the aftershocks. We deployed and maintained this array from June 2015 to May 2016.
The Himalaya have been identified as the region on planet Earth likely to produce the first earthquake killing >1 million people. Earthquakes on the Main Himalayan Thrust and its splays have already killed >100,000 people in this century. Anything that science can do to identify the structure of the Main Himalayan Thrust, particularly the across-strike and along-strike variability in structure that may represent asperities capable of nucleating or limiting the rupture of future earthquakes, will feed into hazard estimation and risk mitigation efforts.
Publications & Presentations
Bai, L., Klemperer, S., Mori, J., Karplus, M., Ding, L., Liu, H., Li, G., Song, B., Dhakal, S., Lateral variation of the Main Himalayan Thrust controls the rupture length of the 2015 Gorkha earthquake in Nepal, in press at Science Advances.
Karplus, M. S., Klemperer, S. L., Zhao, W., Kind, R., Wu, Z., Mechie, J., Shi, D., Brown, L. D., Chen, C., Su, H., Xue, G., Sandvol, E., Ni, J., Tilmann, F. J., Chen, Y. J. (2019), Receiver-function imaging at the Kunlun-Qaidam boundary, Northeast Tibet, in press at Tectonophysics.
Eken, T., Tilmann, F., Mechie, J., Zhao, W., Kind, R., Su, H., Xue, G., Karplus, M. S. (2013), Seismic anisotropy from SKS splitting beneath Northeastern Tibet, Bull. Seis. Soc. Am., doi:10.1785/0120130054.
Karplus, M. S., Klemperer, S. L., Lawrence, J. F., Zhao, W., Mechie, J., Sandvol, E., Ni, J., Tilmann, F. J. (2013), Ambient noise tomography of north Tibet limits geological terrane signature to upper-middle crust, Geophys. Res. Lett., doi:10.1002/grl.50202.
Mechie, J., Zhao, W., Karplus, M. S., Wu, Z., Meissner, R., Shi, D., Klemperer, S. L., Su, H., Kind, R., Xue, G., and Brown, L. D. (2012), Crustal shear (S) velocity and Poisson’s ratio structure along the INDEPTH IV profile in northeast Tibet as derived from wide-angle seismic data, Geophys. J. Int., 191, 369-384, doi:10.1111/j.1365-246X.2012.05616.x.
Karplus, M. S., Zhao, W., Klemperer, S. L., Wu, Z., Mechie, J., Shi, D., Brown, L. D., Chen, C. (2011), Injection of Tibetan crust beneath the south Qaidam Basin: Evidence from INDEPTH wide-angle seismic data, J. Geophys. Res., 116, B07301, doi:10.1029/2010JB007911.
Zhao, W., Kumar, P., Mechie, J., Kind, R., Meissner, R. , Wu, Z. , Shi, D. , Su, H. , Xue, G. , Karplus, M. S. , Tilmann, F. (2011), Tibetan plate overriding the Asian plate in central and northern Tibet, Nature Geoscience, doi: 10.1038/NGEO1309.
Karplus, M. S., Klemperer, S. L., Zhao, W., Wu, Z., Brown, L. D., Shi, D., Mechie, J., Chen, C., Glen, J. (2010), INDEPTH IV Seismic Imaging of Channel Flow Outwards from the Kunlun Mountains Beneath the Qaidam Basin, in Leech, M.L., and others, eds., Proceedings for the 25th Himalaya-Karakorum-Tibet Workshop: U.S. Geological Survey, Open-File Report 2010-1099, 2 p.
Chen, C., Brown, L. D., Karplus, M. S., Klemperer, S. L. (2010), The Golmud Step: New details of the 15 km Moho offset between the Tibet Plateau and the Qaidam Basin from INDEPTH IV seismic results, in Leech, M.L., and others, eds., Proceedings for the 25th Himalaya-Karakorum-Tibet Workshop: U.S. Geological Survey, Open-File Report 2010-1099, 2 p.
Li, Qiusheng, Gao, R., Lu, Z., Guan, Y., Zhang, J., Li, P., Wang, H., He, R., Karplus, M. S. (2009). The thickness and structural characteristics of the crust across Tibetan Plateau from active source seismic profiles. Earthquake Science. 22 (1), 21-31.
Zhao, W., Brown, L.,Wu, Z., Klemperer, S. L., Shi, D., Mechie, J., Su, H., Tilmann, F., Karplus, M. S., and Makovsky, Y. (2008). Seismology across the northeastern edge of the Tibetan Plateau. Eos Transactions. American Geophysical Union, 89 (48).
Karplus, M. S., Klemperer, S., Wenjin, Z., Zhenhan, W., Danian, S., Heping, S., Brown, L., Chen, C., Mechie, J., Kind, R., Tilmann, F., Makovsky, Y., Meissner, R. (2008). Northeast Tibetan Crustal Structure from INDEPTH IV Controlled-Source Seismic Data (extended abstract), Himalayan Journal of Sciences, 5(7), p. 76-77.