Susan Hough is haveing a book released in May 2002 called: Earthshaking Science : What We Know (And Don't Know) About Earthquakes

She is one of the pioneers (as far as I know) on triggered quakes (or one of the first to speak up about it) - She has done some research on the New Madrid quakes and also believes that those quakes in 1811-1812 triggered other quakes in the eastern part of the US.

Unfortunately her web site is down along with the rest of the USGS sites...

Canie