Kachchh Earthquake of 2001: Seismically Triggered Deformed Structures in the Intertidal Sediments of Mandvi Coast in the Gulf of Kachchh, Gujarat

On 26 January 2001, a major earthquake of magnitude of 77 caused extensive damage in Kachchh and other parts of Gujarat Mandvi coast in the Gulf of Kachchh, which is 150 km far from the epicentral zone, is also highly affected by the high magnitude seismic waves causing deformed structures in soft sediments. These induced deformed soft sediment structures are recorded in the small lagoon adjoining the beach area. The structures include sand blows, cracks, micro faulting, deformed Cross-Laminae, flume and pillar structures and large injection structures, which are attributed to intrusion spout phenomena. Abnormal behaviour of suspension feeding squillidean stomatopod, Oratosquilla striata species, was also observed. These structures are interpreted to originated by the process of fluidisation and liquefaction of cohessroniess peaty subsurface layer undeineath the clastic sediments. The shear stress related to earthquake acted as trigger agent.