VolcanoWatch Weekly [23 September 2009]

Magnitude 6.4 EQ occurred off SW of Puerto Vallarta, Jalisco, Mexico, at a depth of 35 km, today.

FEWW Comments: The strong earthquake may have primed for eruption either one or both of two volcanoes Bárcena, which forms the island of San Benedicto, and Socorro, located on island of the same name, about 380 km to the west of the EQ location.

VOW1: Bárcena

Bárcena volcano forms the elongated island of San Benedicto, seen here from the SW in March 1955. The tuff cone with the circular summit crater at the center and the lava delta to the right were formed during an eruption in 1952-53, the only eruption known from this volcano in historical time. Pleistocene trachytic lava domes are located at the far NE tip of the island. Dark-colored lava domes from the 1952-53 eruption can be seen in the summit crater. Photo by Adrian Richards, 1955. Caption: GVP

VOW2: Socorro

Cerro Evermann, the high point of Socorro Island, rises above a Mexican Naval camp near the southern tip of the island. Socorro lies in the Revillagigedo Islands south of Baja California. Cerro Evermann is a large tephra cone and lava dome complex that forms the 1050-m-high summit of the volcano. Rhyolitic lava domes have been constructed along flank rifts, and silicic lava flows erupted from summit and flank vents have created an extremely irregular shoreline. Only minor explosive activity has occurred in historical time. Photo by Martha Marin, 1998 (Mexican Navy). Caption: GVP

Bárcena  and Socorro are shown to the lower left of the map.

SI /USGS Weekly Volcanic Activity Report
(16 September – 22 September 2009)

New activity/Unrest:

• Karymsky, Eastern Kamchatka
• Kliuchevskoi, Central Kamchatka (Russia)
• Sakar, Northeast of New Guinea (SW Pacific)
• Shiveluch, Central Kamchatka (Russia)

News From GVP:

• KVERT reported that although seismic activity from Kliuchevskoi did not exceed background levels during 11-18 September, weak tremor was detected. Strombolian activity that ejected tephra 70 m above the crater was seen at night on 16 and 17 September.

• KVERT reported that during 11-18 September seismic activity from Shiveluch was above background levels. On 13 September, pyroclastic flow deposits 5 km long were seen on the S part of the lava dome.  —GVP

Ongoing Activity:

• Bagana, Bougainville
• Batu Tara, Komba Island (Indonesia)
• Chaitén, Southern Chile
• Dukono, Halmahera
• Kilauea, Hawaii (USA)
• Rabaul, New Britain
• Reventador, Ecuador
• Sakura-jima, Kyushu
• Suwanose-jima, Ryukyu Islands (Japan)

Related Links:

• Messages From Earth’s Powerhouse
• Weekly Volcano Watch: 19 March 2009

• A New Era of Intense Volcanic Unrest May Have Begun
• Tonga’s Metis Shoal may be erupting
• Rumble III Volcano “blew its top!”
• Volcanoes
• Earthquakes

FEWW Volcanic Activity Forecast

• Sumatra’s Mt Kerinci Erupts

• Sumatra’s Mt Kerinci Erupts
• Volcano Watch Weekly: 23 April 2009

• Weekly Volcano Watch: 16 April 2009
• Weekly Volcano Watch: 2 April 2009

• FEWW Volcano Links
• Volcanoes
• FEWW Earthquake Links

Other Related Links:

• U.S. Volcano Status Map
• Elevated Activity Page
• U.S. Volcano Webcams