Tectonic evolution and stress pattern of South Wagad Fault at the Kachchh Rift Basin in western India

Abstract

We describe a study of the E–W-trending South Wagad Fault (SWF) complex at the eastern part of the Kachchh Rift Basin (KRB) in Western India. This basin was filled during Late Cretaceous time, and is presently undergoing tectonic inversion. During the late stage of the inversion cycle, all the principal rift faults were reactivated as transpressional strike-slip faults. The SWF complex shows wrench geometry of an anastomosing en échelon fault, where contractional and extensional segments and offsets alternate along the Principal Deformation Zone (PDZ). Geometric analysis of different segments of the SWF shows that several conjugate faults, which are a combination of R synthetic and R’ antithetic, propagate at a short distance along the PDZ and interact, generating significant fault slip partitioning. Surface morphology of the fault zone revealed three deformation zones: a 500 m to 1 km wide single fault zone; a 5–6 km wide double fault zone; and a c. 500 m wide diffuse fault zone. The single fault zone is represented by a higher stress accumulation which is located close to the epicentre of the 2001 Bhuj earthquake of Mw 7.7. The double fault zone represents moderate stress at releasing bends bounded by two fault branches. The diffuse fault zone represents a low-stress zone where several fault branches join together. Our findings are well corroborated with the available geological and seismological data.

Evolution of Drainage in Response to Brittle - Ductile Dynamics and Surface Processes in Kachchh Rift Basin, Western India

“…A wide zone of fault rupture pattern is investigated in WH of Kachchh peninsula. The seismic structures, seismicity and fault plane solution investigation show that the GF (F4) is a nearly vertical fault (Figure 7B, C) having dominant strike-slip deformation [15,18,51].…”

“…Conventionally, an extensional overstep zone of a strike-slip fault several branches that join together at depth into a single vertical plane [18]. As a consequence, bulk displacement accommodated at depth on the basement fault is distributed towards the surface among several faults whose tectonic activity evolves through time [60].…”

“…The rifting was aborted by the trailing edge uplift during the Late Cretaceous pre-collision stage of the Indian plate, when the leading edge of the plate was slab-pulled towards the Tethyan trench [10,14,16]. Lateral motion during the drift stage of the plate induced horizontal stress and near vertical normal faults, which were reactivated as reverse faults during initiation of the inversion cycle, and became strike-slip faults involving divergent oblique-slip movement [10,14,17,18]. [11]; shows location of earthquake epicenters.…”

Shallow subsurface imaging of the Wagad active fault system (Kachchh, northwestern India) by time domain electromagnetic studies

“…The information on active faults and its subsurface geometry is essentially needed for effective seismic hazard assessment. Many active fault traces were identified in the region based on field (both geophysical and geological) investigations and satellite photo interpretation, which suggested imprints of Holocene to post Tertiary tectonic activity along the faults (Malik et al 2001;Mathew et al 2006;Patidar et al 2007Patidar et al , 2008Maurya et al 2013;Rajendran et al 2008;Chowksey et al 2011;Bhattacharya et al 2013;Kothyari et al 2016). GPR studies by Patidar et al (2007) indicated reactivation of the Kathrol Hill Fault (KHF) under compressive stress and suggested southward directed tilting of the geomorphic features due to neotectonic movements along the KHF.…”

Transient Electromagnetic Investigations in a Tectonic Domain of the Kachchh Intraplate Region, Western India: A Morphotectonic Study of the Kachchh Mainland Fault

“…In spite of many regional geophysical studies, shallow geophysical surveys done in the region are very limited (Mithila & Bansal, ), except a few site‐specific ground‐penetrating radar studies (Chowksey et al, ; Maurya et al, , ). Using the ground‐penetrating radar and coupled with field investigations, many active fault traces were identified in the region that suggested imprints of Holocene to post‐Tertiary tectonic activity along the faults (Kothyari et al, ; Mathew et al, ; Maurya et al, ; Patidar et al, , ; Prizomwala et al, ; Rajendran et al, ). Chowksey et al () have suggested that the KMF is morphologically expressed as E‐W trending steep scarps, while the actual fault line is located further north and is buried under the Quaternary colluvio‐fluvial sediments.…”