Volcano earthquakes and Volcano earthquake notifications – United States – California
California volcanoes with recent proved eruptions
Lassen Volcanic Center - Last eruption 1917
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. (text & image : Smithsonian Institution)
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| USGS | Northern California | Apr 09 05:22 AM | 2.9 | 12 | MAP I Felt It INFO | |
| ER | Lassen Volcanic, California (startup Record) | Jan 01 00:00 AM | 0.1 | 0 | MAP I Felt It | |
| James Daniell CATDAT | United States | Jul 22 08:00 AM | 0.0 | 10 | MAP I Felt It | |
Inyo Craters – Last activity : 1998
The Inyo Craters are a 12-km-long chain of silicic lava domes, lava flows, and explosion craters along the eastern margin of Sierra Nevada south of Mono Craters near the town of Mammoth. Inyo Craters overtop the NW rim of the Pleistocene Long Valley caldera and extend onto the caldera floor, but are chemically and magmatically part of a different volcanic system. Postglacial explosion pits of Mammoth Mountain to the south are an extension of Inyo Craters (Bailey 1980). The latest eruptions at Inyo Craters took place about 600 years ago, when explosive eruptions accompanied formation of the South Deadman, Obsidian Flow, and Glass Creek rhyolitic lava domes and lava flows. The Inyo Crater Lakes are small phreatic craters that formed during this eruption on the south flank of the Pleistocene Deer Mountain rhyolite dome of the Long Valley caldera. (text & image : Smithsonian Institution)
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| ER | Inyo Craters, California (startup Record) | Jan 01 00:00 AM | 0.1 | 0 | MAP I Felt It | |
California Volcanoes with active seismicity
Long Valley
The large 17 x 32 km Long Valley caldera east of the central Sierra Nevada Range formed as a result of the voluminous Bishop Tuff eruption about 760,000 years ago. Resurgent doming in the central part of the caldera occurred shortly afterwards, followed by rhyolitic eruptions from the caldera moat and the eruption of rhyodacite from outer ring fracture vents, ending about 50,000 years ago. During early resurgent doming the caldera was filled with a large lake that left strandlines on the caldera walls and the resurgent dome island; the lake eventually drained through the Owens River Gorge. The caldera remains thermally active, with many hot springs and fumaroles, and has had significant deformation, seismicity, and other unrest in recent years. The late-Pleistocene to Holocene Inyo Craters cut the NW topographic rim of the caldera, and along with Mammoth Mountain on the SW topographic rim, are west of the structural caldera and are chemically and tectonically distinct from the Long Valley magmatic system.
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| USGS | Long Valley Area, California | May 06 03:05 AM | 2.5 | 0 | MAP I Felt It | |
| USGS | Central California | Mar 30 03:19 AM | 3.8 | 9 | MAP I Felt It INFO | |
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| USGS | Long Valley Area, California | Mar 24 08:29 AM | 3.1 | 5 | MAP I Felt It INFO | |
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| USGS | Long Valley Area, California | Nov 01 06:56 AM | 2.5 | 7 | MAP I Felt It | |
| USGS | Long Valley Area, California | Oct 25 16:11 PM | 2.6 | 7 | MAP I Felt It | |
| USGS | Long Valley Area, California | Oct 19 09:15 AM | 2.7 | 7 | MAP I Felt It | |
| USGS | Long Valley Area, California | Oct 19 09:15 AM | 3.0 | 8 | MAP I Felt It | |
| USGS | Long Valley Area, California | Aug 24 00:59 AM | 2.5 | 10 | MAP I Felt It | |
| USGS | Long Valley Area, California | Apr 29 16:05 PM | 2.6 | 4 | MAP I Felt It | |
| USGS | Long Valley Area, California | Apr 26 22:19 PM | 2.6 | 4 | MAP I Felt It | |
| USGS | Long Valley Area, California | Apr 26 21:08 PM | 2.5 | 4 | MAP I Felt It | |
| USGS | Long Valley Area, California | Apr 26 12:20 PM | 2.5 | 4 | MAP I Felt It | |
| USGS | Central California | Jan 21 14:18 PM | 2.5 | 3 | MAP I Felt It | |
| ER | Inyo Craters, California (startup Record) | Jan 01 00:00 AM | 0.1 | 0 | MAP I Felt It | |
| James Daniell CATDAT | United States | Sep 30 07:00 AM | 5.9 | 5 | MAP I Felt It | |





