California Volcanoes , United – States : normal levels of background seismicity and deformation.

California Volcanoes , United – States : normal levels of background seismicity and deformation.

Current Volcano Alert Level: all NORMAL
Current Aviation Color Code: all GREEN

Activity Update: All volcanoes monitored by CalVO using telemetered, real-time sensor networks exhibit normal levels of background seismicity and deformation. Volcanoes monitored include Mount Shasta, Medicine Lake Volcano, Clear Lake Volcanic Field, Lassen Volcanic Center, Long Valley Volcanic Region, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.

Observations for March 1, 2016 through March 31, 2016 :

Mt Shasta: One earthquake at or above M1.0 was detected (M1.06).
Medicine Lake: No earthquakes at or above M1.0 were detected.
Lassen Volcanic Center: Five M1.0 or greater earthquakes were detected, with the largest registering M1.42. Many of these events occurred during two minor seismic swarms on March 23, 2016 near the Shasta-Tehama-Plumas County lines about 14 km north of the town of Mill Creek and March 26, 2016 near the Shasta-Tehama-Plumas County lines about 8 km north of the town of Mineral.
Clear Lake Volcanic Field: Two M1.0 or greater earthquakes were detected, with the largest registering M2.63. [Note: The typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was M2.90].

Long Valley Volcanic Region: In Long Valley Caldera, 16 earthquakes of M1.0 or greater were detected. The largest event registered M2.15. No earthquakes at or above M1.0 were detected in the Mono Craters region. No earthquakes at or above M1.0 were detected under Mammoth Mountain. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.58].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Sixteen earthquakes of M1.0 or greater were detected. The largest registered M2.14.
Coso Volcanic Field: The typical high level of seismicity was observed, with 24 earthquakes M1.0 or greater. The largest registered M2.47.

The Short Story of Ubehebe Crater in Death Valley National Park
March 31, 2016

New research by scientists at CalVO indicates that Ubehebe Craters formed about 2100 years ago during a single eruptive event. Ubehebe Craters are a lone cluster of volcanic craters in the northern half of California’s Death Valley National Park. CalVO geologists Judy Fierstein, Wes Hildreth, and Duane Champion investigated the sequence of rocks to determine whether the 15 craters formed as several independent eruptions over hundreds of years from a long-lasting, deep magma source, or whether they formed at one time.

The scientists are confident that the craters are monogenetic—created during one explosive episode when magma interacted with groundwater, over several days, weeks or months (but certainly not over hundreds of years). Their evidence: first, dozens of layers of rocks ejected during successive eruptive pulses are “conformable”—no time is represented by erosion or anything else between them, so all layers must have fallen during a short-lived eruption sequence. Second, they note that the composition of basaltic cinder samples does not vary—meaning that a single batch of magma fed the multi-crater phreatomagmatic episode. Third, measured paleomagnetic directions are almost exactly the same; again, not much time could have passed between crater-forming pulses.

Short-lived eruptive sequences like the ones that formed Ubehebe Craters are common in volcanically active areas (for example, throughout the Cascade Range). This is the only young volcano in Death Valley National Park, which was otherwise a volcanically quiet area for the last million years.

April 05, 2016.California Volcanoes , United – States :

Source : Calvo

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