Geomorphic imprints of long- and short-term deformation in the Kachchh Intraplate Region (Western India)

Abstract

The Kachchh basin stands out among intraplate regions for having experienced two of the most significant intraplate earthquakes within 200 years: the 1819 Allah Bund earthquake (Mw 7.8) and the 2001 Bhuj earthquake (Mw 7.6). The latter occurred just north of a previously unidentified fault near the region's longest-running fault, i.e., the Kachchh Mainland Fault (KMF). Despite numerous surveys conducted after the 2001 event, no primary rupture was observed along this discontinuity, raising significant questions about the KMF's deformational patterns. This study aims to decipher regional tectonic perturbations throughout the Northern Hill Range (NHR), focusing on the deformational front associated with the KMF and identifying distinctive geomorphic indicators of active tectonics. The investigation reveals variation in tectonic activity along the KMF, with more pronounced and recent activity on the central-eastern side of the NHR. This line of research culminated in paleoseismic trenching near the epicentral region of the 2001 Bhuj earthquake, identifying a paleo-event bracketed between 3.44 ka and 1.84 ka BP.