Are you from / in the north west? Not that that is important. Just curious.
People freaked about Mt St Helens when it blew. That was nothing but a sparkler show in a serious fireworks demonstration.
Mt Mazama. That was big. Memory - probably wrong - tells me that event was about 11,000 years ago. Yellowstone National Park. That was big - several times. A caldera of huge proportions - and now growing - again. Reload.
I have not heard of Steen Mountain - it has actually been several (5 -6) years since I've been actively looking / reading. etc.
Have you been to Idaho - Craters of the Moon, etc? Snake River Plateau, etc?
Several documented cases of the the magnetic fields completely flip-flopping. All from looking at lava. Amazing stuff.
LVM