USGS HOME
Contact USGS

  • About
  • Observatories
  • Activity
  • Education
  • Publications


Activity Updates

Choose Activity Updates: | | | | | | | | | | |
CALIFORNIA VOLCANO OBSERVATORY MONTHLY UPDATE
U.S. Geological Survey
Monday, February 1, 2016 10:17 AM PST (Monday, February 1, 2016 18:17 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 1, 2016 (0000h PST) through January 31, 2016 (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: Eleven M1.0 or greater earthquakes were detected, with the largest registering M2.26. Many of these events occurred during two minor seismic swarms on January 2, 2016 near the Shasta-Tehama-Plumas County lines about 12 km northeast of the town of Mineral and on January 10-11, 2016 near the Tehama-Plumas County line about 15 km east of the town of Mill Creek.
Clear Lake Volcanic Field: Two earthquakes of M1.0 or greater were detected. The largest was M1.18. [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 M2.95].
Long Valley Volcanic Region: In Long Valley Caldera, 7 earthquakes of M1.0 or greater were detected. The largest event registered M1.81. In the Mono Craters region, 5 earthquakes of M1.0 or greater were detected, with the largest registering M2.59. One earthquake of M1.0 or greater was detected under Mammoth Mountain (M1.16). [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.17].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Three earthquakes of M1.0 or greater were detected. The largest registered M2.06.
Coso Volcanic Field: The typical high level of seismicity was observed, with 9 earthquakes M1.0 or greater. The largest registered M2.31.

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, January 4, 2016 12:09 PM PST (Monday, January 4, 2016 20:09 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 December 1, 2015 (0000h PST) through December 31, 2015 (2359h PDT):
Mt Shasta: One M1 or greater earthquake was detected (M1.91).
Medicine Lake: Two M1.0 or greater earthquakes were detected, with the largest registering M1.87.
Lassen Volcanic Center: Two M1.0 or greater earthquakes were detected, with the largest registering M1.45.
Clear Lake Volcanic Field: One earthquake of M1.0 or greater was detected (M1.11). [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 M2.87].
Long Valley Volcanic Region: In Long Valley Caldera, 9 earthquakes of M1.0 or greater were detected. The largest event registered M2.06. In the Mono Craters region, 2 earthquakes of M1.0 or greater were detected, with the largest registering M2.60. 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 event registered M3.28].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Thirteen earthquakes of M1.0 or greater were detected. The largest registered M2.83.
Coso Volcanic Field: The typical high level of seismicity was observed, with 15 earthquakes M1.0 or greater. The largest registered M1.88.

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
Wednesday, December 2, 2015 9:40 AM PST (Wednesday, December 2, 2015 17:40 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, 2015 (0000h PST) through November 30, 2015 (2359h PDT):
Mt Shasta: One M1 or greater earthquake was detected (M1.29).
Medicine Lake: Ten M1.0 or greater earthquakes were detected, with the largest registering M1.76. These earthquakes occurred during a minor seismic swarm on November 12-13 near the Siskiyou-Modoc county line about 4 miles east-northeast of Medicine Lake.
Lassen Volcanic Center: No earthquakes of M1.0 or greater were detected.
Clear Lake Volcanic Field: Three earthquakes of M1.0 or greater were detected. The largest event registered M2.21. [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 M2.78].
Long Valley Volcanic Region: In Long Valley Caldera, 17 earthquakes of M1.0 or greater were detected. The largest event registered M2.00. In the Mono Craters region, 1 earthquake of M1.0 or greater was detected and registered M1.37. One earthquake of M1.0 or greater was detected under Mammoth Mountain (M2.03). [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.60].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Three earthquakes of M1.0 or greater were detected. The largest registered M1.75.
Coso Volcanic Field: The typical high level of seismicity was observed, with 19 earthquakes M1.0 or greater. The largest registered M2.65.

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, November 2, 2015 12:31 PM PST (Monday, November 2, 2015 20:31 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, 2015 (0000h PST) through October 31, 2015 (2359h PDT):
Mt Shasta: Two M1 or greater earthquakes were detected. The largest event registered M1.86.
Medicine Lake: One M1 or greater earthquake was detected (M1.22).
Lassen Volcanic Center: One earthquake of M1.0 or greater was detected (M1.19).
Clear Lake Volcanic Field: Three earthquakes of M1.0 or greater were detected. The largest event registered M1.67. [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 M3.30].
Long Valley Volcanic Region: In Long Valley Caldera, 10 earthquakes of M1.0 or greater were detected. The largest event registered M1.79. In the Mono Craters region, 1 earthquake of M1.0 or greater was detected (M1.44). 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 event registered M2.35].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Six earthquakes of M1.0 or greater were detected. The largest registered M1.79.
Coso Volcanic Field: The typical high level of seismicity was observed, with 12 earthquakes M1.0 or greater. The largest registered M2.05.

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, October 1, 2015 10:14 AM PDT (Thursday, October 1, 2015 17:14 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, 2015 (0000h PST) through September 30, 2015 (2359h PDT):
Mt Shasta: One M1 or greater earthquakes was detected (M1.11).
Medicine Lake: One M1 or greater earthquake was detected (M1.76).
Lassen Volcanic Center: One earthquake of M1.0 or greater was detected (M1.65).
Clear Lake Volcanic Field: One earthquake of M1.0 or greater was detected (M1.64). [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 M3.00].
Long Valley Volcanic Region: In Long Valley Caldera, 9 earthquakes of M1.0 or greater were detected. The largest event registered M3.22. In the Mono Craters region, 17 earthquakes of M1.0 or greater were detected. The largest event was M2.69. Many of these earthquakes occurred during a minor swarm on September 6-7 beneath Mono Lake. 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 event registered M2.59].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Five earthquakes of M1.0 or greater were detected. The largest registered M1.76.
Coso Volcanic Field: The typical high level of seismicity was observed, with 13 earthquakes M1.0 or greater. The largest registered M1.91.

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
Wednesday, September 2, 2015 10:04 AM PDT (Wednesday, September 2, 2015 17:04 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, 2015 (0000h PST) through August 31, 2015 (2359h PDT):
Mt Shasta: No M1 or greater earthquakes were detected.
Medicine Lake: One M1 or greater earthquake was detected (M1.10).
Lassen Volcanic Center: Three earthquakes of M1.0 or greater were detected. The largest registered M2.26.
Clear Lake Volcanic Field: Five earthquakes of M1.0 or greater were detected. The largest registered M2.31. [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 M3.83].
Long Valley Volcanic Region: In Long Valley Caldera, 34 earthquakes of M1.0 or greater were detected. The largest event registered M3.71. In the Mono Craters region, 4 earthquakes of M1.0 or greater were detected. The largest event was M2.09. One earthquake of M1.0 or greater was detected under Mammoth Mountain (M1.11). [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M2.03].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Twelve earthquakes of M1.0 or greater were detected. The largest registered M1.81.
Coso Volcanic Field: The typical high level of seismicity was observed, with 5 earthquakes M1.0 or greater. The largest registered M1.53.

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 3, 2015 2:16 PM PDT (Monday, August 3, 2015 21:16 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, 2015 (0000h PST) through July 31, 2015 (2359h PDT):
Mt Shasta: No M1 or greater earthquakes were detected.
Medicine Lake: Four M1 or greater earthquakes were detected. The largest event was M1.53.
Lassen Volcanic Center: Seventeen earthquakes of M1.0 or greater were detected. The largest registered M2.18. Many of these events occurred during two minor swarms on July 7 and 9, about 12 km northeast of the town of Mill Creek near the Shasta County-Plumas County boarder.
Clear Lake Volcanic Field: One earthquake of M1.0 or greater was detected, of M1.22. [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 M3.83].
Long Valley Volcanic Region: In Long Valley Caldera, 21 earthquakes of M1.0 or greater were detected. The largest event registered M2.77. In the Mono Craters region, 10 earthquakes of M1.0 or greater were detected. The largest event was M2.48. One earthquake of M1.0 or greater was detected under Mammoth Mountain (M1.02). [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest event registered M3.01].
Ubehebe Craters: No earthquakes at or above M1.0 were detected.
Salton Buttes: Three earthquakes of M1.0 or greater were detected. The largest registered M2.75.
Coso Volcanic Field: The typical high level of seismicity was observed, with 10 earthquakes M1.0 or greater. The largest registered M1.96.

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 6, 2015 12:16 PM PDT (Monday, July 6, 2015 19:16 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, 2015 (0000h PST) through June 30, 2015 (2359h PDT):
Mt Shasta: Four M1 or greater earthquakes were detected. The largest registered M1.86.
Medicine Lake: One M1 or greater earthquake was detected (M1.41).
Lassen Volcanic Center: Eight earthquakes of M1.0 or greater were detected. The largest registered M1.80. Many of these events occurred during two minor swarms on June 22-23, about 12 km north-northeast of the town of Mineral near the Shasta County-Tehama County boarder and on June 26, about 12 km northeast of the town of Mill Creek.
Clear Lake Volcanic Field: One earthquake of M1.0 or greater was detected, of M1.32. [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 M2.73].
Long Valley Volcanic Region: In Long Valley Caldera, 9 earthquakes of M1.0 or greater were detected. The largest event registered M2.31. In the Mono Craters region, no earthquakes of M1.0 or greater were detected, and 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 event registered M3.15].
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 5 earthquakes of M1.0 or greater. The largest registered M3.31.
Coso Volcanic Field: The typical high level of seismicity was observed, with 11 earthquakes M1.0 or greater. The largest registered M3.31.

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, June 1, 2015 2:25 PM PDT (Monday, June 1, 2015 21:25 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, 2015 (0000h PST) through May 31, 2015 (2359h PDT):
Mt Shasta: Two M1 or greater earthquakes were detected. The largest registered M1.59.
Medicine Lake: No earthquakes of M1.0 or greater were detected.
Lassen Volcanic Center: One earthquake of M1.0 or greater was detected (M1.85).
Clear Lake Volcanic Field: One earthquake of M1.0 or greater was detected, of M1.10. [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 M2.93].
Long Valley Volcanic Region: In Long Valley Caldera, 45 earthquakes of M1.0 or greater were detected. The largest event registered M2.57. In the Mono Craters region, 24 earthquakes of M1.0 or greater were detected (M2.90 maximum), and 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 M3.34].
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 38 earthquakes of M1.0 or greater. The largest registered M2.89.
Coso Volcanic Field: The typical high level of seismicity was observed, with 27 earthquakes M1.0 or greater. The largest registered M2.68.

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, May 1, 2015 9:46 AM PDT (Friday, May 1, 2015 16:46 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, 2015 (0000h PST) through April 30, 2015 (2359h PDT):
Mt Shasta: One M1 or greater earthquake was detected (M2.07).
Medicine Lake: No earthquakes of M1.0 or greater were detected.
Lassen Volcanic Center: Two earthquakes of M1.0 or greater were detected. The largest registered M2.22.
Clear Lake Volcanic Field: One earthquake of M1.0 or greater was detected, of M1.42. [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 M3.28].
Long Valley Volcanic Region: In Long Valley Caldera, 7 earthquakes of M1.0 or greater were detected. The largest event registered M1.86. In the Mono Craters region, ten earthquakes of M1.0 or greater were detected (M2.48 maximum), and two earthquakes of M1.0 or greater were detected under Mammoth Mountain (M1.77 maximum). [Note: The typical high level of seismicity was observed south of the caldera in the Sierra Nevada range. The largest registered M2.91].
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 13 earthquakes of M1.0 or greater. The largest registered M2.53.
Coso Volcanic Field: The typical high level of seismicity was observed, with 29 earthquakes M1.0 or greater. The largest registered M2.34.

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/.