Is Lassen Peak an active volcano?.
You’ll get different answers depending on whom you ask and where you look. Though the definition of “active volcano” is surprisingly vague, most volcanologists agree that a volcano is active if it has erupted “in recorded historic time”. Prior to Mount St. Helen’s 1980 eruptions, Lassen Peak, the southernmost Cascade Range volcanic mountain, was the most recently eruptive volcano in the continental U.S. In May 1914, Lassen began venting steam and ashes from its peak. The next 12 months saw over 150 more eruptions, some emitting steam/ash clouds almost 2 miles high. The Great Explosion: By May 1915, lava began overflowing Lassen’s summit crater’s walls. On May 19th, a hot rock avalanche was triggered on the east side, resulting in a lahar (lava flow combined with snow and mud) extending 11 miles down Lost Creek. On May 22nd, the climactic “Great Explosion” generated pyroclastic flows, lahars, floods, and a dramatic eruption column that rose 5 ½ miles skyward, dumping fine ash as far eas
