Seismogenesis of earthquakes occurring in the ancient rift basin of Kachchh, Western India - Intraplate Earthquakes - page 138

Figure 6.7 Schematic 3D model displaying Vp distribution with depth. The 2001 Bhuj earthquake
hypocenter (22 km value most accepted, but ranges from 22 to 26 km) shown by a star lies on the
boundary of low- and high-velocity patches. The hatched areas are low-velocity zones while the white
areas mark the high-velocity zones. At a depth of 34 km (not shown) the low-velocity zone is much
larger.
The ABF, KMF, SWF, IBF, and KHF are found to be active by Quaternary movements as
observed in trenches ( Figure 6.8 ; Rajendran and Rajendran 2002 , 2003 ; Malik et al ., 2008 ;
Morino et al ., 2008a, b and www.isr.gujarat.gov.in/Annual Reports 2009-10, 2010-11,
2011-12). This indicates that different faults are active neotectonically. Below we describe
the work of the Institute of Seismological Research (ISR), most of which was done with
Malik and Morino.
The deformation zone of the 1819 Allahbund earthquake of Kachchh was mapped with
a precise elevation survey in an area 80 km long and 6-7 km wide. The amount of uplift
measured in 2007 is up to 5.8 m. By adding 1.8 m estimated erosion since 1819, a total
uplift of 7.6 m is estimated for the 1819 earthquake. The Allahbund fault is interpreted to