The Distribution of Intensity Associated with the 1905 Kangra Earthquake and Bounds on the Extent of the Rupture Zone

In his report of the damage caused by the 1905 Kangra earthquake, Middlemiss (1910) reported two zones of relatively high intensity: a major one with a maximum near Kangra and Dharamsala and extending southeast to Mandi, and a minor one centered around Dehra Dun. A re-examination of the information that he gave suggests that the intervening zone of low intensity was not well-defined and that the intensity near Dehra Dun was not markedly higher than that at towns in the plains of northern India. Thus, these observations allow three different possibilities for the extent of the rupture zone. The rupture may have extended southeast 280 km, from west of Dharamsala to southeast of Dehra Dun. In this case the rupture probably occurred on segments of two thrust faults connected by a strike-slip fault in the hanging wall (or by a buried lateral ramp) north of Simla. Possibly there were two separate ruptures: one extending from near Dharamsala southeast to Mandi and the other, poorly defined, near Dehra Dun. Finally the distribution of destruction allows for the possibilities that only the area 100km in extent, from west of Dharamsala to Mandi, ruptured and that the 1905 earthquake did not relieve much strain in the region near Dehra Dun. Accordingly, it probably is safe to assume that Dharamsala will not lie in the epicentral area of the next great earthquake in the Himalaya, but it probably would be unwise to assume that that area will not include Dehra Dun.