when was the last time mt lassen erupted
Lassen Peak On May 22, 1915, a powerful explosive eruption at Lassen Peak devastated nearby areas, and spread volcanic ash as far as 200 mi (300 km) to the east.[4] This explosion was the most powerful in a series of eruptions from 1914 through 1917. Lassen Peak and Mount St. Helens were the only two volcanoes in the contiguous United States to erupt during the 20th century.[5] Lassen Volcanic National Park was created in Tehama County, California, to preserve the devastated areas as they were, for future observation and study, and to preserve the nearby volcanic features.
Mount Shasta During the last 10,000 years, Mount Shasta has erupted an average of every 800 years, but in the past 4,500 years the volcano has erupted an average of every 600 years. The last significant eruption on Mount Shasta may have occurred about two centuries ago.[3]