Study of Intensities of 26th April 1986 Dbaramshala Earthquake (Himachal Pradesh) and Associated Tectonics

A moderate earthquake of magnitude 5.5 on Richter scale rocked the Dharamshala area in Himachal Pradesh on 26th April 1986 at 07.35 : 17 GMT. The earthquake was felt in Kangra valley, Kullu, Mandi and Chamba areas. Dharamshala town, Macleodganj and Naddi etc., were subjected to maximum damage where the mud houses, older buildings and some of the Govt. buildings suffered maximum loss. Cracks along mortar joints, fall of plaster and relative movement of walls were observed in a number of residential buildings. On the basis of study, four isoseisrnals of VII, VI, V, IV intensities on the MMscale have been drawn. The shape of these isoseismals is elliptical and based on this, the NW/SE trending epicentral tract of this earthquake has been estimated to bel oeated just at Dharamshala Town. With the land levelHng survey and field observation of cracks and fracture, the direction of movement and direction of fracture is also shown. Local depth distribution of earthquake in the Dharamshala area suggests that fractures causing this earthquake have. direct relationship with the local thrust faults.