The phenomenon was thought to result from the body being tricked into producing an effect by itself that would have been brought about by the drugs.

"He was designing with his camera," Squiers says, "and after starting out as a [soft-focus] pictorialist, he brought sharp focus to bear and had a tremendous effect on the field."

The biggest effect may be on the first fault itself: Parts of the fault immediately adjacent to the part that slipped may be brought closer to failure.