The 26 Jan 2001 Bhuj earthquake
Centenary of the 4 April 1905 Kangra earthquake
PUBLICATIONS
Ambraseys, N., and R. Bilham (2003), Earthquakes in Afghanistan, Seism. Res. Lett., 74(2), 107-123. Text.pdf Narrative description of Historic earthquakes
Ambraseys, N., and R. Bilham (2003), Earthquakes and crustal deformation in northern Baluchistan, Bull. Seism Soc. Am. 93 (4), 1573-160, 2003
Bendick, R, and R. Bilham, 1998 A Search for Buckling of the SW Indian Coast related to Himalayan Collision, in Macfarlane, A., Sorkhabi, R. B., and Quade, J., eds., Himalaya and Tibet: Mountain Roots to Mountain Tops: Geol Soc Amer. Special paper 328,
Bendick, R., R. Bilham, E. Fielding, V. K. Gaur, S. Hough, G. Kier, M. N. Kulkarni, S. Martin, K. Mueller and M. Mukul, The January 26, 2001 "Republic Day" Earthquake, India. Seism. Res. Lett., 72(3), 328-335, 2001. (download 484k PDF file)
Bendick, R., and R. Bilham, How perfect is the Himalayan Arc? Geology, 29,791-794, 2001.
Bilham, R., (1994) The Next Great Earthquake in the Nepal Himalaya, Himal Magazine, 7(3), 26-30.
Bilham, R., (1994) The 1737 Calcutta Earthquake and Cyclone Evaluated, Bull. Seism. Soc. Amer. 84(5), 1650-1657. (download 154k PDF file)
Bilham, R., P. Bodin, M. Jackson, (1995) Entertaining a Great Earthquake in Western Nepal:Historic Activity and Geodetic Tests for the Development of Strain, J. Geol.Soc. Nepal, 11, 73-88. (download a 380 k PDF file)
Bilham, R. (1995) Location and magnitude of the 1833 Nepal earthquake and its relation to the rupture zones of contiguous great Himalayan earthquakes, Current Science, 69(2), 155-187. (download a 440k PDF file)
Bilham, R., K. Larson, J. Freymueller and Project Idylhim members, (1997) GPS measurements of present-day convergence across the Nepal Himalaya, Nature(Lond)., 386, 61-64 .
Bilham. R., F. Blume, R. Bendick and V. K. Gaur (1998) . Geodetic constraints on the Translation and Deformation of India: implications for future great Himalayan earthquakes, Current Science, 74,(3), 213-229. (dowload 1.3 Mb PDF file)
Bilham, R., Slip parameters for the Rann of Kachchh, India, 16 June 1819, earthquake, quantified from contemporary accounts (1998) In Stewart, I. S. & Vita-Finzi, C. (Eds) Coastal Tectonics. Geological Society London, 146, 295-318. (Download a 964k PDF file)
Bilham, R., and V. K Gaur, The geodetic contribution to Indian seismotectonics, Current Science 79, 2000. or 256kPDF
Bilham,R, V.K. Gaur, and P. Molnar, Himalayan Seismic Hazard, Science, 293, 1442-4, 2001
Bilham, R., R. Bendick, and K. Wallace, (2003). Flexure of the Indian Plate and intraplate earthquakes, Proc. Indian Acad. Sci. (Earth Planet Sci.),112(3) 1-14 (download 1.7Mb pdf)
Bilham R, and N. Ambraseys, Apparent Himalayan slip deficit from the summation of seismic moments for Himalayan earthquakes, 1500-2000, Current Science 2004 (download 3.5Mb pdf) (download compressed 272k file)
Bilham, R., Earthquakes in India and the Himalaya: tectonics, geodesy and history, Annals of Geophysics, (2004), 47(2), 839-858.
Bürgmann, R., Larson, K. and R. Bilham, Model inversion of GPS and leveling measurements across the Himalaya: Implications for Earthquake Hazards and future geodetic networks, Himalayan Geology, 20, 59-72, 1999.
Freymuller, R. Bilham R. Bürgmann and K. Larson, (1996) Global Positoning System measurements of Indian Plate motion and convergence across the Lesser Himalaya,Geophys. Res. Lett . 23 (22), 3107-3110.
Paul, J., & 10 authors, (1995) Microstrain Stability of Peninsula India 1864-1994, Proc. Indian Acad.Sci.(Earth Planet. Sci.) 104(1).
2003>>Hough S.E, R.Bilham, N. Ambraseys and N.Feldl, Revisiting the 1897 Shillong and 1905 Kangra earthquakes in northern India: Site Response, Moho reflections and a Triggered Earthquake . Current Science, 2004 in the press
Searle, M. P., B. R. Hacker, and R. Bilham, The Hindu Kush seismic zone as a paradigm for the creation of ultra-high pressure diamond and coesite-bearing continental rocks, Journal of Geology, 109, 143-153, 2000.
2003>>Sri Devi Jade and 12 other authors, Pre-seismic, co-seismic and post seismic displacements associated with the Bhuj earthquake derived from recent and historic geodetic data. J. Ind Inst of Sci. 112 (3), 331-346, 2003. (download 500k pdf)
2003>>Wallace, K, G Yin and R. Bilham, Inescapable slow slip on the Altyn Tagh Fault, submitted to Geophys. Res. Lett.. 2004
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The seismic zonation map of India has notable gaps in and south of the Himalaya, where great earthquakes have not occurred in the past 200-300 years but where they are likely to occur in the future. See also Bilham et al. 2003.
The above figure indicates the location, year and number of fatalities (in parenthesis) for earthquakes in India in the past 200 years.. (From Bilham and Gaur, 2000).
Deformation of the Indian Plate and historic earthquakes in India
With two exceptions we find that the southern peninsula of India has deformed very little in the past 160 years. The GPS-derived rate indicates that points in southern and northern India converge by less than 3±2 mm/yr (Paul et al 1995, 2001). The first exception is found on the Malabar coast of India where leveling and tide gauge data indicate the western coast of southern India is apparently sinking rapidly near Cochin (Bendick and Bilham, 1998). Although these data are independent the rapid subsidence rate is puzzling, and historical reports of rapid deformation in the past 1000 years could not be substantiated during field verification. The coast between Bombay and Karachi is a second exception to the apparent geodetic stability of the sub-continent.
A magnitude M>7.7 earthquake occurred in the Rann of Kachchh in 1819 (Bilham, 1998), which Rajendran et al (1998) find to have historical precedent. The January 2001 Gujarat earthquake occurred on the same fault system, although the system is at least 50 km wide. The reportedly extremely destructive Calcutta earthquake of 1737 ( claimed Bengal death toll of 300,000 ) that is still listed in numerous seismic catalogues, is shown to be a cyclone with a death toll of fewer than 3000 (Bilham, 1994). The earthquake geodesy of India is summarized in Bilham et al. (1998), Bilham and Gaur (2000), and Bilham (2004)
Southward (!) motion of India
It may come as a surprise to many geologists, that India is moving southward relative to the Earth's spin axis. This is caused by the vanishing northern ice sheets, and subsequent mantle mass adjustments. The southward rate of motion of India at present is 4 cm/year and Tibet is moving south at 8 cm/year. Even though these rates are much slower than during the initial ice melt 10,000-8,000 years BP, the total shift is less than 100 km. Nevertheless this may have important consequences for understanding the monsoon in the past 5000 years.
Himalayan earthquakes
We currently believe that more than 60% of the Himalaya are overdue for a great earthquake. In Bilham et al. (1998) and Bilham and Gaur (2000) we summarize geodetic data that permit constraints on the rupture geometries of the past four Himalayan M>8 earthquakes (1897, 1905, 1934 and 1950). The data are actually rather poor. The 1898 measurements of Captain J. Bond (!) remain underutilized but indicate that the Shillong Plateau rose 15-20 m in a reverse faulting episode along its northern edge (Bilham and England, 2001. This earthquake thus did not occur in the Himalaya. The remaining 3 earthquakes were sampled only along their southern edges. One important constraint for the 1934 earthquake is that its rupture appears to have terminated close to the Nepal border. A Nepal earthquake in 1833 is shown to have a magnitude less than M=7.9, and to have been located near the NW rupture edge of the 1934 earthquake (Bilham, 1995). The 1905 Kangra earthquake is now believed to have been a M=7.8 event (Ambraseys and Bilham, 2000) whose rupture zone did not approach Dehra Dun as hitherto believed (Bilham, 2001). Hough et al., 2004 show that high iontensities near Dehra Dun are caused by a triggered earthquake. A number of articles articulate the probability that a future great earthquake is overdue in western Nepal (Bilham et al. 1995, Bilham (1994, 1998), Bilham and Gaur, 2000, Bilham et al., 2001. Recent articles include a summary of historical earthquakes in the Himalaya and an analysis of moment deficit (Bilham 2004, Bilham and Ambraseys, 2004).
Translation of India and deformation in the Himalaya
In Freymuller et al (1996), Bilham et al (1997) and Larson et al. 1999 we document the 53-63 mm/year NE motion of India towards Asia that results a 19-24 mm/yr shortening rate across the Himalaya. The velocities are based on 5 years of data. In Paul et al., 1995, 2001 we discuss the geodetic stability of the Indian plate. Articles on seismicity in Baluchistan and Afghanistan discuss slip rates on the Chaman fault system (Ambraseys and Bilham 2003,2004). A small tsunami in 1881 is used to constrain the seismicity of the Andaman Islands (Ortiz and Bilham 2002).
Outreach
Because our results have important implications for seismic risk for the people of India and Nepal we have chosen to publish many of our articles in Indian and Nepali journals. Copies of these articles can be obtained from the authors or downloaded from this web page.