How many times has Mt. Rainier erupted?

Mt. Rainier has erupted 11 confirmed times in the last 10,000 years. Most of these eruptions (8) are concentrated between 6500 and 4000 years ago. Since the eruption 2,200 years ago there has only been one recorded explosive eruption as identified and dated through airfall tephra and tree ring dating. This eruption was believed to be between 1820 and 1854 AD. For further information on the more distant geologic history and understanding of future risks from Mt. Rainier see related links to the Cascades Volcano Observatory.