Looks like this earthquake may well have been triggered by the continual movement of the Indian plate into the Asian continent. The Himalaya Mts were, and are still being, formed from this slow motion collision which began around 50 million years ago.
Geology of the Himalayas (Origins and growth):
"In the Upper Cretaceous (84 Million yrs ago), the Indian plate began its very rapid northward drift at an average speed of 16 cm/year, covering a distance of about 6000 km [~3600 miles], until the collision of the northwestern part of the Indian passive margin with Eurasia in early Eocene time (48-52 Million yrs ago). Since that time and until today, the Indian continent continues its northwards movement at a slower but still surprisingly fast rate of ~5 cm/year..."
http://en.wikipedia.org/wiki/Geology_of_the_Himalaya