Relative Assessment of Tectonic Activity along the Seismically Active Katrol Hill Fault, Kachchh, Western India

Abstract

ABSTRACT The Katrol hill fault (KHF) is a 71 km long fault, striking E-W in the Kachchh intraplate region, western India which is moderately active, seismically, but exhibit high strain rate with considerable vertical deformation. It is dissected by several young transverse faults. Based on these transverse faults, KHF is longitudinally, divided into five segments. Even though there are evidences of its active nature during the Holocene Period, no studies have been carried out for quantifying the spatial variation in relative tectonic activity along the KHF, which is vital for assessing a more realistic seismic hazard potential of the fault. Quantitative geomorphic indices are employed to evaluate the ‘Relative Index of Tectonic Activity (RITA)’. It has been observed that the central part (segment 2 & 3) is the most active segment, which covers an aerial extent of 38% of total KHF (class 1), compared to the eastern (segment 4 & 5) and the western segments (segment 1), which are moderately active (class 2). Interestingly none of the segments of the KHF, corresponded to class 3 of RITA i.e. least active/inactive class. The study highlights the important role of transverse faults, which cut across the major E-W faults in the Kachchh, and may regulate the relative activity and the earthquake potential of an individual segment. The study thus, hints the KHF as an under-rated source for future seismic hazard for the Kachchh and western India region.