Recent earthquake swarms in Garhwal Himalaya: A precursor to moderate to great earthquakes in the region

摘要

Himalayas, one of the most seismically active belts, have been formed due to continent-continent collision and are probable locations for future moderate to great earthquakes. It is of paramount importance to recognize precursory swarm activity considered to be long predictors of main events. Recently two earthquake swarms occurred across Main Central Thrust (MCT) in Garhwal Himalayan region in a time interval of nearly one month. The first swarm of April 2009 had epicentral locations lying north of MCT on hanging wall side, which has shown less seismic activity in recent times, while the second swarm occurred in May 2009 near Copeshwar having epicenters on active seismic zone, located south of MCT. The approximate distance between the two swarms is about 50 km. In present study preparation zone of 100 × 100 km~2 has been demarcated recognizing these swarms as precursors to moderate to great earthquake in the Garhwal Himalaya.