Wayne N Edwards 1 Peter G Brown 1

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Wayne N. Edwards 1, Peter G. Brown 1, David Mc. Cormack 2 Ottawa, Ontario K 1 A 0 E 8, Canada 1 Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N 6 A 3 K 7, Canada. 2 Natural Resources Canada, 1 2 Sarnia, Ontario: December 13, 2006 Imperial Oil Refinery Explosion 3 Ilderton, Ontario: April 24, 2007 Methamphetamine Lab Explosion In the early morning hours of December 14 th, residents of Sarnia, Ontario were awakened by a loud, thunderous explosion from one of the hydrocracking units from the Imperial Oil Refinery located at the southern border of the city (42. 950°N, -82. 416°W, Fig. 1 a). The 18, 000 -82. 416°W barrel/day unit was responsible for processing and upgrading heavy oils unsuited for gasoline or diesel fuel. The ensuing fire (Fig. 1 b) was contained to the single unit. Located at a range of 93 km from the Elginfield Infrasound array (ELFO) the infrasonic blast was observed at 8: 02: 49 UT (Bk. Az: 257. 1° ± 0. 6, Vapp: 341 ± 1 m/s) consistent with a direct tropospheric path (Figure 1 c). The observation assisted investigators and structural engineers by constraining the time of the explosion to ~07: 56 UT (2: 56 am local EST), and its estimated yield at between the equivalent of 5 – 10 tons of TNT using amplitude and period measurements (Whitaker 1995). At ~10 pm an explosion from a rural farm house at 11543 Ilderton Road (43. 0566°N, 81. 4411°W) was reported by area residents. The resulting fire engulfed the home as dozens of regional volunteer firefighters fought to contain it. Police remarked that the two-storey home had its entire north and rear walls blown outward revealing the interior of the home before the fire had ignited. One man was rescued and taken to hospital for burns and smoke inhalation, while his wife and two children escaped uninjured. The family dog was killed. While house fires are not unusual, these reports of an explosion prompted a search for infrasound from the event for confirmation. At 2: 09: 30 UT (10: 09: 30 EDT) a short, 30 second impulse from the direction of the home (195. 4°) was discovered (Fig 2). From period and amplitude measurements of the pulse the explosion was equivalent to ~160 lbs of equivalent TNT (Whitaker 1995). No damage (broken windows etc. ) to the nearby buildings, nor injuries to on-duty workers were reported. The cause of the explosion was not released. Investigations discovered the explosion was caused by ignition of chemicals in the basement due to an illegal drug and marijuana lab. The man and wife were charged with: arson with disregard for human life, arson with negligence, possession and production of drugs and marijuana for the purpose of trafficking. (b) At dusk on August 10, 2008 the Downsview region of the city of Toronto, Ontario was rocked by two powerful explosions from the Sunrise Propane Industrial Gases Storage Facility south of the Downsview airport (43. 733°N, -79. 473°W, Fig. 3 b). This resulted in a fire that engulfed the -79. 473°W entire facility, causing several more powerful explosions as propane tanks erupted. Surrounding residential homes were damaged as windows shattered and doors were taken off hinges. The explosions caused the evacuation of thousands of residents over 1. 6 km wide area and shut down al 16 lanes of nearby HWY-401 (Canada’s busiest highway). The fireball and explosions could be seen for many km’s as it rose more than 200 m into the sky. One firefighter and a Sunrise employee were killed. ELFO observed several arrivals from the multiple explosions (Fig. 3 a). Azimuths and time delays are consistent with direct topospheric arrivals for the two main explosions, while a low amplitude wavetrain small explosions/fire) can be seen afterwards for ~9 min. Yield estimates for the two main explosions give: 46 -128 & 118 -125 tons of eq. TNT (a) ns ct e w vie Air Af fe (b) w Do (a) Toronto, Ontario: August 10, 2006 Propane Storage Facility Explosion rt po d. A re a #1 Initial Explosion (c) 1 km Figure 2 Figure 1 Duration #3 Enduring wavetrain Sunrise Propane Facility Figure 3 4 -“Mystery Blasts” n y Ba Subsequent “rumble” ia 31 st, Huron Wurtsmith AFB BMRO BRCO Alpena Calcite Open-pit Mines Audible “Bangs” (coupled seismically below) (a) rg 207 Around 11 pm EDT on July 2008, residents of Kincardine, Ontario were awakened by two loud, thunderous bangs emanating from somewhere over Lake Huron. The sounds, as reported by residents, were apparently loud enough to rattle windows and objects on walls. Initial guesses as to the source of the “thunder” were (1) a perseid meteor, (2) an accident at a regional nuclear power plant, (3) nearby salt mine blasting (4) supersonic aircraft. ELFO infrasound showed that two blasts were observed at 02: 12: 30 UT along with a series of inaudible phases (Fig. 4 a) arriving from 315 -323 ° (Vapp: 348353 m/s). These observations (along with all-sky cameras) ruled out a meteor source, as well as operations at the Bruce Nuclear Power Plant, while Goderich salt mine logs eliminated it as a source. The impulses were also observed seismically as ground coupled acoustic waves around South Western Ontario and Northern Michigan (Fig. 4 b). From observed back azimuths and particle motions observed at seismic sites, the source of the two blasts was identified as originating from an area in Northern Michigan (45. 04± 0. 12°N, 83. 62± 0. 21°W, 44. 905± 0. 061°N 83. 492± 0. 047°W) with a probable origin time of ~2: 59 UT with explosive yields between 2 -3 tons on TNT (Whitaker 1995), consistent with quarry-type explosions. Wurtsmith AFB and restricted airspace R-4207 lie near this region, but AF activities ceased in 1993 and local airport radar reported no aircraft in the area at the time. The Alpena open pit calcite mine, however, lies only 18 km NE. If the sounds were blasts from the mine, seismic phases should have arrived at the stations at ~03: 01 UT. Such arrivals can be readily identified at several stations. It appears that due to propagation conditions, Kincardine lay near a convergence of sound propagating from explosions at the Alpena mine (a known source of other inaudible signals at ELFO). Inaudible “bangs” TOBO Lake Figure 4 Kincardine, Ontario: August 1, 2008 – Mysterious Explosions over Lake Huron 401 eo G ~30 second pulse (above) of the explosion which destroyed an Ilderton house (right). Hwy R-4 4 #2 Explosion BWLO BASO 3 -Sunrise Propane Seismically coupled acoustic wave ELFO BASO BRCO BMRO BWLO CLWO ELFO TOBO AAM (b) CLWO 1 -Imperial Oil 2 -Meth. Lab AAM ke La rie E

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