May 20, 1992 Earthquake: Peshawar, Kohat, Shakkar Khel, Pakistan

1992, May 20. At least 36 people killed and 100 injured in the Peshawar and Kohat Districts, including 20 people killed at Shakkor Khel. At least 400 houses destroyed in the Kohat District, Felt at Islamabad and Lahore. Also felt in the Srinagar area. Kashmir and in parts of northern India. (reference #1053)

1992, May 20. 36 deaths, 2100 affected. (reference #1250)

Throughout most of the Himalaya, slip of the Indian Plate is restrained by friction on the interface between the plate and the overlying wedge of Himalayan rocks. Every few hundred years, this interface-or decollement-ruptures in one or more Mw>8 earthquakes. In contrast, in the westernmost Himalaya, the Indian Plate slips aseismically beneath wide plateaux fronting the Kohistan Mountains. The plateaux are underlain by viscous decollements that are unable to sustain large earthquakes. Potwar, the widest of these plateaux is underlain by viscous salt, which currently permits it to slide at rates of about 3mmyr-1, much slower than its 2 Myr average. This deceleration has been attributed to recently increased

friction through the loss of salt from its decollement. Here

we use interferometric synthetic aperture radar and seismic

data to assess movement of the Kohat Plateau-the narrowest

and thickest plateau. We find that in 1992 an 80 km2 patch of the décollement ruptured in a rare Mw6.0 earthquake, suggesting that parts of the decollement are locally grounded. We conclude that this hybrid seismic and aseismic behaviour represents an evolution of the mode of slip of the plateaux from steady creep towards increasingly widespread seismic rupture. (reference #9725)