Initial acoustic source is determined to be at Mount St. Helens vent (photo a) and triangle in map).  Subsequent acoustic source about 3.5 minutes later is located about 9 km to the Northwest with lowest source residuals in the vicinity of the Toutle River Drainage (circle) and corresponds quite nicely with visual evidence for a displaced plume somewhere to the north of the volcano.

ß J. Christensen photos from Mount Adams about 3-5 minutes after 8:32:11 PDT