Can scientists predict the timing and type of future volcanic eruptions?
The best guide to predicting the nature of future eruptions of Mount Rainier is geologic evidence left by previous eruptions. By studying this evidence, scientists have identified the types of possible events including debris flows, ashfall, volcanic blasts, and lava flowsand their likely size. But a volcano’s history cannot be used to make specific predictions about when the next eruption will occur. Mount Rainier erupts sporadically, with periods of inactivity that typically last for centuries. Oral histories of Northwest native peoples mention eruptions of Mount Rainier, and at least two small eruptions occurred in the 19th century, during the early years of U.S. settlement of the region. The last giant eruption- triggered debris flow occurred about 500 years ago, and the last lava flows that added new rock to the volcano’s summit occurred between 1,200 and 2,100 years ago.
