Lassen Volcanic National Park, national park in northeastern California, established in 1907. The park has as its main feature the volcanic Lassen Peak (3,187 m/10,457 ft). After remaining inactive for more than 400 years, it erupted in May 1914 and continued to erupt more or less constantly until 1917 and intermittently until 1921. Activity during that period was characterized by numerous explosions and by a massive, destructive mudslide, formed when hot lava melted snow on the mountain’s slopes. Other smaller volcanic peaks in the park are Cinder Cone (2,107 m/6,913 ft), Prospect Peak (2,543 m/8,342 ft), and Harkness Peak (2,450 m/8,039 ft). Cinder Cone is devoid of vegetation and surrounded by piles of volcanic cinder and ash. The park also features many alpine lakes, fumaroles (vapor-emitting vents), hot springs, boiling mud pots, and lava formations. Area, 43,047 hectares (106,372 acres).

Reviewed by: National Park Service