page_title: Lassen Peak
hierarchical_section_title: Lassen Peak
caption_attribution_description: English: Lassen Peak in Lassen Volcanic National Park as seen from the shore of frozen Lake Helen on June 12, 2020.
context_page_description: Lassen Peak, commonly referred to as Mount Lassen, is the southernmost active volcano in the Cascade Range of the Western United States. Located in the Shasta Cascade region of Northern California, it is part of the Cascade Volcanic Arc, which stretches from southwestern British Columbia to northern California. Lassen Peak reaches an elevation of 10,457 feet, standing above the northern Sacramento Valley. It supports many flora and fauna among its diverse habitats, which are subject to frequent snowfall and reach high elevations.
  A lava dome, Lassen Peak has a volume of 0.6 cubic miles making it the largest lava dome on Earth. The volcano arose from the destroyed northern flank of now-collapsed Brokeoff Volcano about 27,000 years ago, from a series of eruptions over the course of a few years. The mountain has been significantly eroded by glaciers over the last 25,000 years, and is now covered in talus deposits.
  On May 22, 1915, a powerful explosive eruption at Lassen Peak devastated nearby areas, and spread volcanic ash as far as 280 miles to the east. This explosion was the most powerful in a series of eruptions from 1914 through 1917. Lassen Peak and Mount St.
context_section_description: Lassen Peak, commonly referred to as Mount Lassen, is the southernmost active volcano in the Cascade Range of the Western United States. Located in the Shasta Cascade region of Northern California, it is part of the Cascade Volcanic Arc, which stretches from southwestern British Columbia to northern California. Lassen Peak reaches an elevation of 10,457 feet (3,187 m), standing above the northern Sacramento Valley. It supports many flora and fauna among its diverse habitats, which are subject to frequent snowfall and reach high elevations.
  A lava dome, Lassen Peak has a volume of 0.6 cubic miles (2.5 km³) making it the largest lava dome on Earth. The volcano arose from the destroyed northern flank of now-collapsed Brokeoff Volcano about 27,000 years ago, from a series of eruptions over the course of a few years.  The mountain has been significantly eroded by glaciers over the last 25,000 years, and is now covered in talus deposits.
  On May 22, 1915, a powerful explosive eruption at Lassen Peak devastated nearby areas, and spread volcanic ash as far as 280 miles (450 km) to the east. 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.
  Lassen Volcanic National Park, which encompasses an area of 106,372 acres (430.47 km²), was created to preserve the areas affected by the eruption, for future observation and study,  to protect the nearby volcanic features,  and to keep away anyone from settling too close to the volcano. The park, along with the nearby Lassen National Forest and Lassen Peak, have become popular destinations for recreational activities, including climbing, hiking, backpacking, snowshoeing, kayaking, and backcountry skiing. Lassen Peak is still considered alive, meaning the volcano is merely asleep, and it has a functioning magma chamber under the ground still capable of eruptions. Thus it poses a threat to the nearby area through lava flows, pyroclastic flows, lahars (volcanically induced mudslides, landslides, and debris flows), ash, avalanches, and floods. To monitor this threat, Lassen Peak and the surrounding vicinity are closely observed with sensors by the California Volcano Observatory.
caption: Lassen Peak volcano
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