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CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
U.S. Geological Survey
Monday, November 10, 2014 3:30 PM PST (Monday, November 10, 2014 23:30 UTC)


Monitored CALIFORNIA VOLCANOES

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 October 1, 2014 (0000h PDST) through October 31, 2014 (2359h PDST):

Mt Shasta:: No earthquakes of M1.0 or greater were detected.

Medicine Lake: No earthquakes of M1.0 or greater were detected.

Lassen Volcanic Center: A modest swarm of low-magnitude earthquakes occurred about 25 miles NW of the town of Chester on October 3-12. There were close to 10 earthquakes of M1.0 or greater, with the largest registering M2.1.

Clear Lake Volcanic Field: Two earthquakes above magnitude 1.0 were detected (M1.32 and M1.77) [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was M=3.59].

Long Valley Volcanic Region: The robust swarm of earthquakes in Long Valley caldera that occurred at the end of last month died off in early October, declining from over 300 earthquakes at the peak of the swarm (September 26; M1.0 or greater) to less than 10 earthquakes per day by October 4. In total, 50 earthquakes of M1.0 and greater were detected within the caldera in October, with the largest registering M2.83. Only one magnitude M1.22 earthquake was detected along the Mono-Inyo chain and no earthquakes at or above M1.0 were detected under Mammoth Mountain. [Note: A persistent earthquake swarm occurred throughout the month of October in the Sierra Nevada Range south of Long Valley caldera in the vicinity of Mount Huntington. More than 100 earthquakes were recorded, the largest of which was M3.6.]

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes: The typical high level of seismicity was observed in the vicinity of the buttes, with 10 earthquakes of M1.0 or greater. The largest registered M2.22.

Coso Volcanic Field: The typical high level of seismicity was observed, with 15 earthquakes M1.0 or greater. The largest registered M2.39.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Monday, October 6, 2014 12:50 PM PDT (Monday, October 6, 2014 19:50 UTC)


Monitored CALIFORNIA VOLCANOES

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 September 1, 2014 (0000h PDST) through September 30, 2014 (2359h PDST):

Mt Shasta:: Only one M1.14 earthquake was detected this month. However, on the afternoon of September 20, a large volume of water surged down Mount Shasta's south flank into Mud Creek, entraining debris and inundating the drainage and roads near McCloud, California. USGS CalVO seismologists determined that the event was not triggered by volcanic or seismic activity. The preliminary assessment of scientists at the Shasta-Trinity National Forest is that the debris flow was triggered by rapid release of melting subglacial water from the Konwakiton Glacier and/or rapid release of ponded water from the adjacent Summit Plateau.

Medicine Lake: Three earthquakes of M1.0 or greater were detected. The largest registered was a M1.95.

Lassen Volcanic Center: Three earthquakes of M1.0 or greater were detected. The largest registered was a M1.76.

Clear Lake Volcanic Field: Five earthquakes of M1.0 or greater were detected. The largest registered was a M1.90. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest registered was a M2.72].

Long Valley Volcanic Region: From September 25th to the 28th a robust earthquake swarm occurred in Long Valley Caldera approximately 7 miles east of the town of Mammoth Lakes. During the swarm, there were more than 600 earthquakes of magnitude M1.0 or greater, and over 100 above magnitude M2.0, including five above magnitude M3.0 (maximum M3.54, revised from preliminary value of M3.8). There was no evidence for anomalous ground deformation attributable to subsurface magma migration. Only two small earthquakes were detected along the Mono-Inyo chain, the largest of which was a M1.52. No earthquakes of M1.0 or greater 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 registered was a M1.98].

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes: The typical high level of seismicity was observed in the vicinity of the buttes, with seven earthquakes of M1.0 or greater. The largest registered M2.65.

Coso Volcanic Field: The typical high level of seismicity was observed, with fourteen earthquakes M1.0 or greater. The largest registered M3.10.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Tuesday, September 30, 2014 2:18 PM PDT (Tuesday, September 30, 2014 21:18 UTC)


Monitored CALIFORNIA VOLCANOES

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 August 1, 2014 (0000h PDST) through August 31, 2014 (2359h PDST):

Mt Shasta:: No earthquakes of M1.0 or greater were detected.

Medicine Lake: No earthquakes of M1.0 or greater were detected.

Lassen Volcanic Center: One earthquake of M2.29 was detected.

Clear Lake Volcanic Field: Seven earthquakes of M1.0 or greater were detected. The largest registered was M2.22. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest registered was M2.87].

Long Valley Volcanic Region: Twelve small earthquakes M1.0 or greater occurred in Long Valley Caldera. The largest caldera quake was a M2.21. Only one magnitude M1.17 earthquake was detected along the Mono-Inyo chain. No earthquakes of M1.0 or greater 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 registered M2.80].

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes:The typical high level of seismicity was observed in the vicinity of the buttes, with eleven earthquakes of M1.0 or greater. The largest registered M2.14.

Coso Volcanic Field:The typical high level of seismicity was observed, with 12 earthquakes M1.0 or greater. The largest registered M1.97.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Wednesday, August 13, 2014 10:48 AM PDT (Wednesday, August 13, 2014 17:48 UTC)


Monitored CALIFORNIA VOLCANOES

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 July 1, 2014 (0000h PDST) through July 31, 2014 (2359h PDST):

Mt Shasta:: One M1.04 earthquake was detected.

Medicine Lake: No earthquakes of M1.0 or greater were detected.

Lassen Volcanic Center: No earthquakes of M1.0 or greater were detected.

Clear Lake Volcanic Field: Two earthquakes were detected, with the largest registering M1.91. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF with a maximum of M2.42].

Long Valley Volcanic Region: A robust swarm of about 200 small earthquakes occurred in Long Valley Caldera on July 7-8. The swarm originated at depths of 5-9 km, and the largest event was a M2.79. No unusual deformation was detected over this period and it posed no immediate hazard. No earthquakes at or above M1.0 were detected along the Mono-Inyo chain or under Mammoth Mountain. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range with a maximum of M2.90].

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes:The typical high level of seismicity was observed in the vicinity of the buttes, with 11 earthquakes at or above M1.0. The maximum registered M3.20.

Coso Volcanic Field: The typical high level of seismicity was observed, with 15 earthquakes at or above M1.0. The maximum registered M2.77.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Wednesday, July 9, 2014 6:19 PM PDT (Thursday, July 10, 2014 01:19 UTC)


Monitored CALIFORNIA VOLCANOES

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 June 1, 2014 (0000h PDST) through June 30, 2014 (2359h PDST):

Mt Shasta:: Three earthquakes of M1.0 or greater were detected with a maximum of M1.83.

Medicine Lake: One earthquake of M1.0 or greater (M2.01).

Lassen Volcanic Center: Two earthquakes of M1.0 or greater were detected with a maximum of M1.67.

Clear Lake Volcanic Field: Eight M1.0 or greater earthquakes were detected with a maximum of M2.18. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF with a maximum of M2.87].

Long Valley Volcanic Region: Seventy-three earthquakes of M1.0 or greater were located in the Long Valley Caldera with the largest events registering M2.41, M2.32, M2.18. The M2.18 event was the largest within a brisk, but short swarm of > 180 earthquakes occurring on June 27-28 at a depth of 6-7 km beneath Hwy 203 in Mammoth Lakes, midway between the water treatment plant and the Highway 395-203 junction. No ground deformation was associated with the swarm, and it posed no immediate hazard. North of the caldera, only one earthquake was detected along the Mono-Inyo chain (M2.07), and no earthquakes M1.0 or greater were detected below Mammoth Mountain on the western rim of the caldera. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range with a maximum of M2.88].

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes:Only one earthquake detected at or above M1.0 (M1.52).

Coso Volcanic Field: The typical high level of seismicity was observed, with nine earthquakes above M1.0 and greater with a maximum of M1.54.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Monday, June 9, 2014 12:01 PM PDT (Monday, June 9, 2014 19:01 UTC)


Monitored CALIFORNIA VOLCANOES

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 Caldera and Mono-Inyo Chain, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.





Observations for May 1, 2014 (0000h PDST) through May 31, 2014 (2359h PDST):

Mt Shasta:: Eight earthquakes of M1.0 or greater were detected with a maximum of M1.40.

Medicine Lake: Two earthquakes of M1.0 or greater were detected with M1.56 maximum.

Lassen Volcanic Center: Seven earthquakes of M1.0 or greater were detected with M1.81 maximum.

Clear Lake Volcanic Field: Two M1.0 or greater earthquakes were detected with a M1.77 maximum. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was a M3.29].

Long Valley Caldera and Mono-Inyo Chain: Forty-three earthquakes of M1.0 or greater were located in the Long Valley Caldera with maximum M2.91. No earthquakes greater or equal to magnitude 1.0 were detected under Mammoth Mountain. Three earthquakes of M1.0 or greater were detected under the Mono-Inyo chain with M2.07 maximum. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event was M3.24]

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes: The typical high level of seismicity was observed in the vicinity of the buttes, with five earthquakes above M1.0 and greater with M2.40 maximum.

Coso Volcanic Field: The typical high level of seismicity was observed, with eleven earthquakes above M1.0 and greater with M1.98 maximum.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Tuesday, May 27, 2014 10:57 AM PDT (Tuesday, May 27, 2014 17:57 UTC)


Monitored CALIFORNIA VOLCANOES

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 Caldera and Mono-Inyo Chain, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.





Observations for April 1, 2014 (0000h PDST) through April 30, 2014 (2359h PDST):

Mt Shasta:: No earthquakes of M1.0 or greater were detected.

Medicine Lake: Three earthquakes of M1.0 or greater were detected with M1.44 maximum.

Lassen Volcanic Center: Three earthquakes of M1.0 or greater were detected with M2.06 maximum.

Clear Lake Volcanic Field: No M1.0 or greater earthquakes were detected. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was a M2.98].

Long Valley Caldera and Mono-Inyo Chain: The earthquake swarm that occurred beneath Mammoth Mountain in February subsided, with no M>1 earthquakes in April (although several M<1.0 earthquakes were detected, as usual). Elsewhere in the region, eighty-eight earthquakes of M1.0 or greater were located in the Long Valley Caldera with maximum M2.61. Two earthquakes of M1.0 or greater were detected under the Mono-Inyo chain with M1.3 maximum. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event was M2.24]

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes: The typical high level of seismicity was observed in the vicinity of the buttes, with thirteen earthquakes above M1.0 and greater with M2.07 maximum.

Coso Volcanic Field: The typical high level of seismicity was observed, with twelve earthquakes above M1.0 and greater with M2.83 maximum.

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Friday, April 11, 2014 12:32 PM PDT (Friday, April 11, 2014 19:32 UTC)


Monitored CALIFORNIA VOLCANOES

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 Caldera and Mono-Inyo Chain, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.





Observations for March 1, 2014 (0000h PST) through March 31, 2014 (2359h PDST):

Mt Shasta:: Three earthquakes of M1.0 or greater were detected; the largest was a M2.0.

Medicine Lake: No earthquakes of M1.0 or greater were detected.

Lassen Volcanic Center: Six earthquakes of M1.0 or greater were detected (M 1.4 maximum).

Clear Lake Volcanic Field: Six M1.0 or greater earthquakes were detected. The largest earthquake was a M1.9. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was a M2.8].

Long Valley Caldera and Mono-Inyo Chain: The earthquake swarm that occurred beneath Mammoth Mountain in February subsided, with only one M1.1 earthquake in March (although several M<1.0 earthquakes were detected, as usual). Elsewhere in the region, thirty-eight earthquakes of M1.0 or greater were located in the Long Valley Caldera (maximum M2.7). Two earthquakes of M1.0 or greater were detected under the Mono-Inyo chain (M1.6 maximum). [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event was M2.7]

Ubehebe Craters: No earthquakes at or above M1.0 were detected.

Salton Buttes: The typical high level of seismicity was observed in the vicinity of the buttes, with twenty-nine earthquakes above M1.0 and greater (M3.4 maximum).

Coso Volcanic Field: The typical high level of seismicity was observed, with thirty-eight earthquakes above M1.0 and greater (M3.1 maximum).

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.



As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.





CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Tuesday, March 11, 2014 4:34 PM PDT (Tuesday, March 11, 2014 23:34 UTC)


Monitored CALIFORNIA VOLCANOES
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. Real-time monitoring networks are in place at Mount Shasta, Medicine Lake Volcano, Clear Lake Volcanic Field, Lassen Volcanic Center, Long Valley Caldera and Mono-Inyo Chain.


Observations for February 1, 2014 (0000h PST) through February 28, 2014 (2359h PST):
Mt Shasta:: No earthquakes of M1.0 or greater were detected.
Medicine Lake: One earthquake of M1.0 or greater (M 1.8) was detected.
Lassen Volcanic Center: Three earthquakes of M1.0 or greater (largest M 1.5) were detected.
Clear Lake Volcanic Field: Three M1.0 or greater earthquakes were detected. The largest earthquake was a M1.2. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was a M2.9].
Long Valley Caldera and Mono-Inyo Chain: An earthquake swarm occurred beneath Mammoth Mountain, lasting from about February 3-18. Though Mammoth Mountain is the site of frequent earthquake swarms, this was one of the largest since a protracted swarm in 1989. The February swarm included 166 earthquakes of M1.0 or larger, most at depths of ~5 km below the surface. The largest event was M 3.1 on Feb 5, which was felt by some residents of the town of Mammoth Lakes. The swarm is likely related to migration of deep-seated hydrothermal fluids. No accompanying changes in surface deformation or gas emissions have yet been detected. Elsewhere in the region, forty earthquakes of M1.0 or greater were located in the Long Valley Caldera, with a maximum M2.6. No earthquakes M1.0 or greater were detected under the Mono-Inyo chain. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event was M2.5]

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.

As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.

CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
Tuesday, February 11, 2014 4:34 PM PST (Wednesday, February 12, 2014 00:34 UTC)


Monitored CALIFORNIA VOLCANOES
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. Real-time monitoring networks are in place at Mount Shasta, Medicine Lake Volcano, Clear Lake Volcanic Field, Lassen Volcanic Center, Long Valley Caldera and Mono-Inyo Chain.


Observations for January 1, 2014 (0000h PST) through January 31, 2014 (2359h PST):
Mt Shasta:: No earthquakes of M1.0 or greater were detected.
Medicine Lake: No earthquakes of M1.0 or greater were detected.
Lassen Volcanic Center: One M1.0 earthquake was detected.
Clear Lake Volcanic Field: Eight M1.0 or greater earthquakes were detected. The largest earthquake was a M1.9. [Note: Typical high level of seismicity was observed under the Geysers steam field located at the western margin of CLVF. The largest event was a M4.5].
Long Valley Caldera and Mono-Inyo Chain: Fifteen earthquakes of M1.0 or greater were located in the Long Valley Caldera, with a maximum M2.3. Four earthquakes M1.0 or greater were detected under the Mono-Inyo chain, with the maximum M1.6. Nine M1.0 or greater earthquakes were detected under Mammoth Mountain. The maximum was M2.0. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event was M2.6]

The U.S. Geological Survey will continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted. For a definition of alert levels see http://volcanoes.usgs.gov/activity/alertsystem/icons.php.

As part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. For additional USGS CalVO volcano information, background, images, and other graphics visit http://volcanoes.usgs.gov/observatories/calvo/. For general information on the USGS Volcano Hazard Program http://volcanoes.usgs.gov. Statewide seismic information for California and Nevada can be found at http://earthquake.usgs.gov/earthquakes/recenteqscanv/.