Mid-1800âs
Small steam and ash explosions
About 200 years ago
Lava dome at Crater Rock; pyroclastic flows, lahars in south
and west valleys, and minor tephra falls
About 1,500 years ago
Debris avalanche from upper south flank; lava dome near
Crater Rock, pyroclastic flows, lahars in south and west
valleys; substantial tephra falls near volcano
30,000 to 15,000 years ago
Multiple episodes of lava dome growth, pyroclastic flows,
lava flows, lahars, and tephra fall; valleys on all flanks
affected