Characteristics of Deformation and Past Seismicity Associated with the 1819 Kutch Earthquake, Northwestern India

The 1819 earthquake in Kutch, northwestern India, is one of the most significant events to have occurred in a plate-interior setting. Despite being the second largest among the stable continental region (SCR) earthquakes, this event has not been analyzed within the context of present-day understanding of earthquake seismology. Coseismic changes related to this earthquake include massive ground deformation in a wide low-lying tidal-flat area. Although detailed historic accounts of this earthquake exist, many questions regarding the mode of deformation and the seismic history of the region remain unresolved. We explored the region nearly 180 years after the earthquake, and the information gathered adds to our understanding of this event and provides a fresh perspective on this unique intraplate seismogenic zone. A 90-km-long tract of elevated land with a peak height of 4.3 m is the most visible surface expression of this earthquake. We surveyed and analyzed the morphological features of this scarp and also carried out exploratory trenching in this region. The scarp morphology is suggestive of a growing fold related to a buried north-dipping thrust rather than a discrete fault that could have resulted from a surface rupture. The extensive liquefaction field associated with the earthquake offered an ideal setting to explore the paleoearthquake history. Age data of liquefaction features suggest that a previous event of comparable size must have occurred 800–1000 years ago. Seismic activity appears to be related to the reactivation of an ancient rift in a stress regime that is dominated by nearly north–south compression.