Available Weekly Reports
|Lassen Volcanic Center|
There are no activity reports for Lassen Volcanic Center.
Summary of eruption dates and Volcanic Explosivity Indices (VEI).
|Start Date||Stop Date||Eruption Certainty||VEI||Evidence||Activity Area or Unit|
|1914 May 30||1917 Jun 29||Confirmed||2||Historical||Lassen Peak|
|1666 (?)||Unknown||Confirmed||3||Dendrochronology||Cinder Cone|
|[ 1650 (?) ]||[ Unknown ]||Uncertain||Chaos Crags|
|980 ± 300 years||Unknown||Confirmed||Radiocarbon (corrected)||Chaos Crags|
|880 ± 300 years||Unknown||Confirmed||Radiocarbon (corrected)||Chaos Crags|
|800 ± 300 years||Unknown||Confirmed||Radiocarbon (corrected)||Chaos Crags|
The Lassen volcanic center consists of the andesitic Brokeoff stratovolcano SW of Lassen Peak, a dacitic lava dome field, and peripheral small andesitic shield volcanoes and large lava flows, primarily on the Central Plateau NE of Lassen Peak. A series of eruptions from Lassen Peak from 1914 to 1917 marks the most recent eruptive activity in the southern Cascade Range. Activity spanning 600,000 years began with construction of Brokeoff stratovolcano. Beginning 400,000 years ago activity shifted to the north flank of Brokeoff, where episodic, more silicic eruptions produced a field of a dozen dacitic lava domes including Bumpass Mountain, Mount Helen, Ski Heil Peak, and Reading Peak. At least 12 eruptive episodes took place during the past 100,000 years, with Lassen Peak being constructed about 28,000 years ago. The Chaos Crags dome complex was constructed about 1100-1000 years ago north of Lassen Peak. The Cinder Cone complex NE of Lassen Peak was erupted in a single episode several hundred years before present and is considered part of the Lassen volcanic center (Clynne et al., 2000). The 1914-1917 eruptions of Lassen Peak began with phreatic eruptions and included emplacement of a small summit lava dome, subplinian explosions, mudflows, and pyroclastic flows.