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CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
U.S. Geological Survey
Friday, February 1, 2019, 11:17 AM PST (Friday, February 1, 2019, 19:17 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 January 17, 2019 (0000h PST) through January 31, 2019 (2359h PST):
Mt Shasta: No earthquakes at or above M1.0 were detected.
Medicine Lake: No earthquakes at or above M1.0 were detected.
Lassen Volcanic Center: One M1.02 earthquake was detected.
Clear Lake Volcanic Field: No earthquakes at or above M1.0 were detected. [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 M2.50].
Long Valley Volcanic Region: In Long Valley Caldera, 18 earthquakes of M1.0 or greater were detected, with the largest registering M3.19. Four earthquakes at or above M1.0 were detected in the Mono Craters region, with the largest registering M2.40. 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, with the largest registering M2.57.]
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Sixteen earthquakes were detected registering M1.0 or greater, with the largest registering M3.08. Many of these events were recorded during several minor seismic swarms that occurred on January 17-20, about 7 miles northwest of Calipatria.
Coso Volcanic Field: Five earthquakes of M1.0 or greater were detected, with the largest registering M2.23.


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
U.S. Geological Survey
Thursday, January 17, 2019, 2:03 PM PST (Thursday, January 17, 2019, 22:03 UTC)


During the current federal government shutdown, the Volcano Hazard Program and all five U.S. Volcano Observatories will continue to issue volcano monitoring updates, warnings, and notifications through the usual channels, including websites, email, and social media. Observatory activities other than those pertaining to protecting life and property are curtailed until further notice. More information is available at https://www.doi.gov/shutdown.

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 December 21, 2018 (0000h PST) through January 17, 2018 (1200h PST):
Mt Shasta: Three earthquakes in the M1.0 range were detected on the south flank of the volcano. All were within 10 km of the summit.
Medicine Lake: No earthquakes at or above M1.0 were detected.
Lassen Volcanic Center: One M1.7 earthquake was detected about 11 km north of Mineral.
Clear Lake Volcanic Field: No earthquakes at or above M1.0 were detected. [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 M3.2].
Long Valley Volcanic Region: In Long Valley Caldera, 18 earthquakes of M1.0 or greater were detected, with the largest registering M2.3. Many of the caldera earthquakes, including the M2.3, were observed during a minor seismic swarm that occurred January 14-16 in a location about 14 km east of Mammoth Lakes. No earthquakes at or above M1.0 were detected in the Mono Craters region. Two earthquakes at or above M1.0 were detected under Mammoth Mountain, with the larger event registering M2.2. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event, a M3.3 on January 11, was located about 16 km southwest of Toms Place].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Thirty earthquakes were detected registering M1.0 or greater. The largest, at 6:41 pm on January 16, was a M3.9.
Coso Volcanic Field: Seven earthquakes of M1.0 or greater were detected, with the largest registering M1.7.


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
U.S. Geological Survey
Monday, December 3, 2018, 10:09 AM PST (Monday, December 3, 2018, 18:09 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 November 1, 2018 (0000h PST) through November 30, 2018 (2359h PDT):
Mt Shasta: No earthquakes at or above M1.0 were detected.
Medicine Lake: No earthquakes at or above M1.0 were detected.
Lassen Volcanic Center: Two earthquakes at or above M1.0 were detected, with the largest event registering M1.78.
Clear Lake Volcanic Field: No earthquakes at or above M1.0 were detected. [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 M2.47].
Long Valley Volcanic Region: In Long Valley Caldera, 22 earthquakes of M1.0 or greater were detected, with the largest event registering M2.43. One earthquake at or above M1.0 was detected in the Mono Craters region (M1.45). Sixteen earthquakes at or above M1.0 were detected under Mammoth Mountain, with the largest event registering M2.18. Many of these earthquakes were observed during a minor seismic swarm that occurred on November 26, 2018 ~3 miles west of Mammoth Lakes. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M1.90].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Twenty-nine earthquakes of M1.0 or greater were detected, with the largest registering M2.53.
Coso Volcanic Field: Thirty-four earthquakes of M1.0 or greater were detected, with the largest registering M2.64.


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
U.S. Geological Survey
Thursday, November 1, 2018, 9:32 AM PDT (Thursday, November 1, 2018, 16:32 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 Volcanic Region, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.


Observations for October 1, 2018 (0000h PST) through October 31, 2018 (2359h PDT):
Mt Shasta: One earthquake at or above M1.0 was detected, registering M1.69.
Medicine Lake: One earthquake at or above M1.0 was detected, registering M1.21.
Lassen Volcanic Center: No earthquakes at or above M1.0 were detected.
Clear Lake Volcanic Field: Two earthquakes at or above M1.0 were detected, with the largest event registering M1.44. [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 M3.35].
Long Valley Volcanic Region: In Long Valley Caldera, 14 earthquakes of M1.0 or greater were detected, with the largest event registering M1.78. One earthquake at or above M1.0 was detected in the Mono Craters region (M1.56). Three earthquakes at or above M1.0 were detected under Mammoth Mountain. The largest event registered M1.46. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.28].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Twenty-seven earthquakes of M1.0 or greater were detected, with the largest registering M2.85.
Coso Volcanic Field: Ten earthquakes of M1.0 or greater were detected, with the largest registering M1.99.


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
U.S. Geological Survey
Monday, October 1, 2018, 10:10 AM PDT (Monday, October 1, 2018, 17:10 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, 2018 (0000h PST) through September 30, 2018 (2359h PDT):
Mt Shasta: One earthquake at or above M1.0 was detected, registering M1.65.
Medicine Lake: One earthquake at or above M1.0 was detected, registering M1.26.
Lassen Volcanic Center: No earthquakes at or above M1.0 were detected.
Clear Lake Volcanic Field: One earthquake at or above M1.0 was detected, registering M1.52. [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 M3.76].
Long Valley Volcanic Region: In Long Valley Caldera, 25 earthquakes of M1.0 or greater were detected, with the largest event registering M2.69. One earthquake at or above M1.0 was detected in the Mono Craters region (M1.36). Four earthquakes at or above M1.0 were detected under Mammoth Mountain. The largest event registered M1.61. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.85].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Five earthquakes of M1.0 or greater were detected, with the largest registering M2.08.
Coso Volcanic Field: Five earthquakes of M1.0 or greater were detected, with the largest registering M1.85.


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
U.S. Geological Survey
Monday, September 10, 2018, 10:27 AM PDT (Monday, September 10, 2018, 17:27 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, 2018 (0000h PST) through August 31, 2018 (2359h PDT):
Mt Shasta: One earthquake at or above M1.0 was detected, registering M1.12.
Medicine Lake: No earthquakes at or above M1.0 were detected.
Lassen Volcanic Center: No earthquakes at or above M1.0 were detected.
Clear Lake Volcanic Field: No earthquakes at or above M1.0 were detected. [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 M3.27].
Long Valley Volcanic Region: In Long Valley Caldera, 74 earthquakes of M1.0 or greater were detected, with the largest event registering M2.93. 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 M2.78].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Two earthquakes of M1.0 or greater were detected, with the largest registering M1.71.
Coso Volcanic Field: No earthquakes at or above M1.0 were detected.


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
U.S. Geological Survey
Monday, August 6, 2018, 1:39 PM PDT (Monday, August 6, 2018, 20:39 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, 2018 (0000h PST) through July 31, 2018 (2359h PDT):
Mt Shasta: No earthquakes at or above M1.0 were detected.
Medicine Lake: No earthquakes at or above M1.0 were detected.
Lassen Volcanic Center: No earthquakes at or above M1.0 were detected.
Clear Lake Volcanic Field: No earthquakes at or above M1.0 were detected. [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 M3.44].
Long Valley Volcanic Region: In Long Valley Caldera, 59 earthquakes of M1.0 or greater were detected, with the largest event registering M2.98. Two earthquakes of M1.0 or greater were detected in the Mono Craters region. The largest event was M1.67. Ten earthquakes of M1.0 or greater were detected under Mammoth Mountain, with the largest registering M1.43. Most of these events occurred during a minor seismic swarm on July 29-31 about three miles southwest of Mammoth Lakes. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.67].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Fifteen earthquakes of M1.0 or greater were detected, with the largest registering M2.71.
Coso Volcanic Field: Sixteen earthquakes of M1.0 or greater were detected. The largest registered M1.64.


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
U.S. Geological Survey
Monday, July 2, 2018, 1:48 PM PDT (Monday, July 2, 2018, 20:48 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 June 1, 2018 (0000h PST) through June 30, 2018 (2359h PDT):
Mt Shasta: One earthquake of M1.0 or greater was detected (M1.12).
Medicine Lake: Two earthquakes of M1.0 or greater were detected, with the largest event registering M1.13.
Lassen Volcanic Center: Four earthquakes of M1.0 or greater were detected, with the largest event registering M1.37.
Clear Lake Volcanic Field: No earthquakes at or above M1.0 were detected. [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 M3.22].
Long Valley Volcanic Region: In Long Valley Caldera, 44 earthquakes of M1.0 or greater were detected, with the largest event registering M2.61. No earthquakes at or above M1.0 were detected in the Mono Craters region. Two earthquakes of M1.0 or greater were detected under Mammoth Mountain, with the largest registering M1.91. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.26].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Four earthquakes of M1.0 or greater were detected, with the largest registering M2.22.
Coso Volcanic Field: Seventeen earthquakes of M1.0 or greater were detected, with the largest registering M1.84.


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
U.S. Geological Survey
Friday, June 1, 2018, 11:47 AM PDT (Friday, June 1, 2018, 18:47 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 May 1, 2018 (0000h PST) through May 31, 2018 (2359h PDT):
Mt Shasta: One earthquake of M1.0 or greater was detected (M1.25).
Medicine Lake: One earthquake of M1.0 or greater was detected (M1.32).
Lassen Volcanic Center: Two earthquakes of M1.0 or greater were detected, with the largest event registering M1.39.
Clear Lake Volcanic Field: Three earthquakes of M1.0 or greater were detected, with the largest event registering M1.90. [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 M4.19].
Long Valley Volcanic Region: In Long Valley Caldera, 30 earthquakes of M1.0 or greater were detected, with the largest event registering M2.19. Four earthquakes of M1.0 or greater were detected in the Mono Craters region. The largest registered M2.96. Three earthquakes of M1.0 or greater were detected under Mammoth Mountain, with the largest registering M1.48. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.22].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Twenty-one earthquakes of M1.0 or greater were detected, with the largest registering M2.19.
Coso Volcanic Field: Fifteen earthquakes of M1.0 or greater were detected, with the largest registering M2.03.


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
U.S. Geological Survey
Tuesday, May 1, 2018, 10:23 AM PDT (Tuesday, May 1, 2018, 17:23 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 April 1, 2018 (0000h PST) through April 30, 2018 (2359h PDT):
Mt Shasta: One earthquake of M1.0 or greater was detected (M1.61).
Medicine Lake: Five earthquakes of M1.0 or greater were detected, with the largest event registering M1.26.
Lassen Volcanic Center: One earthquake of M1.0 or greater was detected (M1.32).
Clear Lake Volcanic Field: Five earthquakes of M1.0 or greater were detected, with the largest event registering M2.02. [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 M3.49].
Long Valley Volcanic Region: In Long Valley Caldera, 53 earthquakes of M1.0 or greater were detected, with the largest event registering M2.57. Six earthquakes of M1.0 or greater were detected in the Mono Craters region. The largest registered M2.28. Six earthquakes of M1.0 or greater were detected under Mammoth Mountain, with the largest registering M1.95. [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.29].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Two earthquakes of M1.0 or greater were detected, with the largest registering M2.26.
Coso Volcanic Field: Fifteen earthquakes of M1.0 or greater were detected, with the largest registering M2.17.


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/.