Okay, so how do you seiso/geo guys map faults underwater? Ultrasound? How do you know how they dip? How do you know how deep they run? How do you know how often they are prone to slip, or thrust, etc.? How do you even know if they are strike slip faults or thrust faults, or something in between? If strike slip, how do you know the direction?

I'm talking about faults not banded by land, such as the San Gregorio off my little strip of coast. That would seem easy (maybe): You measure the fault where it hits land, and where it came from on land. But what about oceanic faults that have no land masses to gauge any parameters from?

Thanks,

Cathryn