Thursday, September 18, 2014
Acoustic puzzle
I heard a series of big explosions from 9:30 to 10 AM. These explosions were clearly coming from NW, sounded like several miles away.
Local news (and by Local News I mean the Spokane-News facebook page) has been covering a house fire fairly close to here. According to these reports there were a number of explosions from stuff in a garage, perhaps stored ammunition, during the exact same time period.
Puzzle: The fire is straight East of me, about one mile. The booms I heard were unquestionably from the NW, not from the East. The only thing I heard from the East was lots of sirens.
A few of the Spokane-News commenters also heard booms from far off to the NW, before the fire to the East was reported.
Were there two separate sets of explosions? Highly unlikely. Much more likely: the explosions from the East (which is strongly uphill from here) passed over me and bounced back from the west bluff of the river.
Frequency-dependent acoustic channeling effect. Maybe.
¶ 10:34 AM 
Frequency-dependent acoustic channeling effect. Maybe.
¶ 10:34 AM
