seismogenic depth for indian himalaya fault plan?

Answer 1

It is an advice, go through the theory of ISOSTASY BY PRAT AND AIERY
FAULT PLANE WILL ALWAYS BE AT THE DEPTH EQUAL TO THREE TIMES THE HEIGHT OF THE OVERLYING OBJECT.
IT IS AN OBSERVATION, HEIGHT OF HIMALAYA FROM DATUM PLANE(NOT FROM SEA LEVEL) IS NEARLY FOUR KILOMETER AND THE FAULT PLANE WILL BE 4X3=12 KMS deep .For further discussion, send email on [e-mail]

Answer 2

I believe your question is :
"What is the depth of the Himalayan fault plane under India as determined from seismic events ?"

The depth of the Himalayan Fault Plane is perhaps 8-10 km in the area under Ganga Plain. It reaches about 10-15 km under the areas called the Sub-Himalaya and Lesser Himalaya. When it reached the area termed the High Himalaya, is starts dipping more steeply and reaches 40 kms and more as it goes north under the Tethyan Himalaya.