JABALPUR EARTHQUAKE OF MAY 22, 1997 - CONSTRAINT FROM AFTERSHOCK STUDY

Macroseismic and microseismic (aftershock) investigations were carried out by the Geological Survey of India immediately after the Jabalpur earthquake (M 6.0) of May 22, 1997. The meizoseismal area of an intens ity Vm (MSK) is 35 km long and 15 km wide, trending ENE-WSW. The after shock investigation was carried out by a five-station temporary microe arthquake (MEQ) network. Five felt aftershocks (M greater than or equa l to 3.0) and 23 aftershocks in the magnitude range 1.5 to < 3.0 were recorded by the network. These are mostly clustered in an elongated ar ea, 15 x 10 km, near the main shock epicentre, and occurred at a depth range 35-40 km which is compatible with that of the main shock. The f ault-plane solution of the main shock and the aftershocks revealed rev erse faulting with left-lateral strike-slip component. The hypocentral section and the fault-plane solutions indicate that the pre-existing ENE-WSW trending Narmada South Fault is deep-rooted to mantle depth, a nd has been activated at the crust-mantle boundary to produce the main shock and the aftershocks. The failure appears to be caused in respon se to the northward post collisional movement of the Indian plate.