We thank John Northrop for his interest in our recent Eos article and for providing us with the opportunity to clarify some important points.
Before commenting on the particulars of Northrop's letter, we must emphasize that we are not claiming to be the originators of a new field called forensic seismology. To the best of our knowledge, the term “forensic seismology” was coined by the British seismologist H.I.S. Thirlaway in the late 1950s to describe what is now known as verification seismology [Thirlaway, 1979]. We are merely extending this catchy phrase to include the investigation of non-nuclear, man-made seismic sources that are accidental or unanticipated.