Lassen Peak ( LASS-ən), commonly referred to as Mount Lassen, is a 10,457-foot (3,187 m) lava dome volcano in Lassen Volcanic National Park in Northern California. Located in the Shasta Cascade region above the northern Sacramento Valley, it is the southernmost active volcano in the Cascade Range of the Western United States, and part of the Cascade Volcanic Arc stretching from southwestern British Columbia to Northern California. It supports many flora and fauna among its diverse habitats, which reach high elevations and are subject to frequent snowfall. Lassen Peak has a volume of 0.6 cu mi (2.5 km3), making it the largest lava domes on Earth. The volcano arose from the former northern flank of now-eroded Mount Tehama 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 mi (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 in Washington were the only two volcanoes within 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 anyone from settling too close to the mountain. 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 dormant, meaning the volcano is merely inactive, 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.
Geography
Lassen Peak lies within Lassen Volcanic National Park, in Shasta County, California, 55 mi (89 km) east of the city of Redding. Lassen Peak and the rest of the National Park area are surrounded by the Lassen National Forest, which has an area of 1,200,000 acres (4,900 km2). Nearby towns include Mineral in Tehama County and Viola in Shasta County. Lassen Peak reaches an elevation of 10,440 ft (3,180 m), according to 1992 data from the U.S. National Geodetic Survey; 1981 data from the Geographic Names Information System lists the mountain's elevation at 10,457 ft (3,187 m). Lassen Peak marks the southernmost major volcano in the Cascade Range, rising above the northern Sacramento Valley. Bounded by the Sacramento Valley and the Klamath Mountains to the west and the Sierra Nevada mountain range to the south, it is the second tallest peak in the California segment of the Cascades, behind the 14,179-foot (4,322 m) Mount Shasta, which lies 80 mi (130 km) to the north. Due to its proximity to nearby volcanoes Mount Tehama and Mount Diller, it is not easy to distinguish from its neighboring peaks.
Physical geography Lassen Peak has the highest known winter snowfall amounts in California, with an average annual snowfall of 660 in (1,676 cm); in some years, more than 1,000 in (2,500 cm) of snow falls at its base elevation of 8,250 ft (2,515 m) at Lake Helen. The Lassen Peak area receives more precipitation (rain, sleet, hail, snow, etc.) than anywhere in the Cascade Range south of the Three Sisters volcanoes in Oregon. Though the volcano lies too far to the south to support a permanent snow cover over the entire mountain, the heavy annual snowfall on Lassen Peak creates fourteen permanent patches of snow on and around the mountain top, but no glaciers. Lightning has been known to strike the area frequently during summer thunderstorms. These can initiate fires. On July 23, 2012, a lightning strike started the Reading Fire 1 mi (1.6 km) to the northeast of the Paradise Meadow region, which was contained after it reached an area of 28,079 acres (113.63 km2). During the summer and fall of 2016, the National Park Service carried out prescribed fires to help reduce the amount of fuel available for fires in the Mineral Headquarters area and the Manzanita and Juniper Lake areas, respectively.
Climate
Ecology Lassen Peak supports a variety of flora that include mountain hemlock, whitebark pine, and alpine wildflowers. Mountain hemlocks generally only reach an elevation of 9,200 ft (2,800 m), while whitebark pines reach up to 10,000 ft (3,000 m). Throughout the national park, forests can be found featuring red fir, mountain alder, western white pine, white fir, lodgepole pine, Jeffrey pine, ponderosa pine, incense cedar, juniper, and live oak. Other plants found in the Lassen Peak area consist of coyote mint, lupines, mule's ears, ferns, corn lilies, red mountain heathers, pinemat manzanitas, greenleaf manzanitas, bush chinquapins, catchflies, Fremont's butterweed, buckwheat, granite gilia, mountain pride, mariposa tulips, creambush, and a variety of chaparral shrubs.
Geology
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