Lahars [ violent mudflows or debris flows composed of a slurry of pyroclastic material, rocky debris, and water that travel down the slopes of a volcano, typically along river valleys ] from Rainer's past eruptions covered ground as far as south Seattle.
Long ago, a geologist said that due to it height [ 14,400 feet ] the pressure of an eruption would not find a ready outlet [ like blowing the top off ], but explode the entire mountain, devastating everything from Portland to the Canadian border. Millions would be killed instantly from the blast force, the flying house sized boulders, the molten lava and rock ash.