Surface deformation in the region of the 1905 Kangra Mw = 7.8 earthquake in the period 1846–2001

Abstract

One century after the Mw = 7.8 Kangra earthquake of 4 April 1905, we report weak constraints on its rupture parameters based on the remeasurement of historic triangulation points in the epicentral region. The western corner of the 1905 rupture is constrained to within 20 km and its SW edge strikes N135 ± 15W. The down-dip width of the rupture is inferred from the location of the interseismic locking-line to have been less than 55 km. Scaling laws and revised MSK intensities suggest an along-arc rupture length of ≈100 km with uniform slip of ∼4 m. Because the earthquake ruptured <60% of the width of the plate boundary and released a fraction of the inferred slip deficit, complacency about its re-rupture in the distant future is unwarranted. The Kangra rupture could fail again today in a Mw = 7.5 earthquake (1.4 m of slip) or as part of a much larger earthquake (Mw ≈ 8.6).