It depends upon the scale, the degree of accuracy you're looking for, and the level of mapping done.

The USGS is notoriously great with their quad maps, but so are most of the state surveys.

And the Brits are GREAT with their mapping.....still among, if not the best in the world.

The hard part is wading through the languages.

Are you looking for a source of *all* fault maps or did you have a particular geographic area/region in mind?

I am looking for global undersea and land faulting maps. obviously maybe not all necessarily one one map, just access to that info.

btw, I love the usgs site! also I have some printed maps of sea floor faults, but many are vague or incomplete in areas. and I am aware of gov't information access issues, scientific blind-spots and unknowables, etc but it seems as if most of what I have and what I have found is pretty dated, or really dated, and I would like to think we have some better technology floating around these days but perhaps I'm living in the future...ha!