My dad says back in the '50s he used to play up on Mount Tabor, and on a cold day he could see steam rising from the crater. How dormant/active is Mount Tabor, and is it true Rocky Butte is actually the top of Tabor that blew off?
I hate to break this to you, Derek, but you can't believe everything Dad says. For example, that time when you were 5, he didn't really have your nose. Also, when he told you you'd go blind—well, you probably figured that one out on your own.
Mount Tabor is one of at least 32 cinder cones that arose from the delightfully named Boring Lava Field a little over 2 million years ago. That makes them over twice as old as Mount Hood, and in their advanced state of decrepitude, they're pretty well washed-up in the erupting business. (I feel their pain.)
In fact, none of these vents has been active for at least 300,000 years, so unless Dad's a lot older than he's letting on, he couldn't have seen any true volcanic activity from them.
As to Dad's other claim: Turns out Rocky Butte rose from the same Boring lavas at the same boring time as Mount Tabor. And in any case, when the Boring volcanoes were active, they erupted with leisurely, viscous flows, not the explosive, Krakatoa-like force that would be necessary to blast a mountain-sized piece of terrain from Tabor to Rocky Butte.
I don't doubt your Dad saw something, but it was probably mist rising from the trees, automobile exhaust, or smoke from the cooking fires of the mole people. The time he spent the Christmas money at the track, then told you Santa Claus had died? That was a lie. This, I'm sure, was an honest mistake.