Oh, ok, you must not live in a area where fracking is occurring, as you seem to suggest that fracking causing earthquakes is not happening, or are not man made...when the op is saying man made, I think they mean are induced by human interaction rather than naturally. Fracking involves injecting water and or other fluids at extreme pressure, to crack layers of rock. this method is supposedly eroding supporting bedrock and putting pressure on fault lines in the area that are normally stable. They are also causing a large number of sink holes in our area. In this context, they are the result of man's actions, and therefore man made.
The tech involved is still just not practiable to be weoponized.