So, this month's accretionary wedge is the most memorable/significant geologic event you've ever experienced.
I haven't personally experienced a truly significant geologic event. I consider that a good thing - escaping flowing lava or having your house fall down around your ears may make for a good story, but I'd rather not live through them.
I suppose the most significant geologic events I've experienced were earthquakes - nothing spectacular, but for the east coast, they were pretty big deals. The most recent? This one in August.
I was in a city that was utterly unprepared for earthquakes, so what happened? Everybody ran outside, under the facades of the buildings (worst idea ever) and generally panicked and acted dumb. Me, I was standing in a reinforced doorway with 2 other geologists while everyone else in the office wondered what the hell we were doing.
That's about enough excitement for me...