Washington state's Mount Rainier last erupted between 1894 and 1895, according to Geology.com. Residents of nearby cities heard explosions coming from the volcano's summit. The last magmatic eruption the volcano experienced was over 1,000 years ago. Geologists believe that Mt. Rainier is due to erupt again in the near future.
Mt. Rainier is a dangerous volcano because of its proximity to densely populated areas such as Seattle and Tacoma. Geologists believe that its next eruption is unlikely to produce plumes of lava. Instead, they are worried about lahars and pyroclastic flows. These avalanches of hot rock, melted ice and snow, huge boulders and volumes of mud could easily bury the surrounding countryside. Great clouds of volcanic ash could also interfere with air traffic and communications.