What caused Sunday's PDX Boom?

The calls started rolling into KATU just after 8 p.m. Sunday, reporting shaking homes from Southeast 84th Avenue and Flavel Street to Southeast 33rd Avenue and Hawthorne Boulevard to Northeast 122nd Avenue and Airport Way. Others said they heard the sound of an explosion, from as far away as Happy Valley.

Firefighters searched for an explosion, and found nothing in the minutes even hours after the boom rocked Portland. Sergeant Greg Stewart with the Portland Police Bureau reports that police and fire personnel have been dispatched throughout the city to investigate the source of the boom.

"I spoke with dispatch and they told me that both PPB and fire investigated but have not identified the cause," Stewart tells KATU.

Meanwhile, air traffic reported no sightings of a fire ball. Also, insiders told us a sound that stretches for more than 100 blocks would likely have to be some sort of aerial sonic boom. However, while windows rattled there were no reports of windows actually blowing out – as could happen in the course of a sonic boom.

We checked with the commander of the Oregon Air National Guard, Bruce Prunk. He said as far as he knows this was not military related. He said the Air Base in Portland was not running a training mission at any point Sunday night, given the weather system that is moving in. He is continuing to check, but at least confirmed this had nothing to do with any fighters from the Oregon Air National Guard.

Also, Western Air Defense – which is part of NORAD – does not show any records during this time-frame that would indicate the boom was aircraft-related.

Note that it is against federal air traffic control regulations to go faster than the speed of sound. This is the speed at which a sonic boom is created.

We also checked on reports from the National Weather Service. The spokesperson there tells us the PDX Boom was not weather related. No lightning strikes or thunder have moved in with the current weather system – just rain.

A spokesperson for Portland General Electric tells us they have had no power outages related to the PDX Boom. There is a small outage in Sandy Sunday evening, but we're told the electricity went out there "pre-boom."

KATU is continuing to follow this story, and will bring you updates as soon as they are available.

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