A couple of weeks ago, I posted about the swarm of earthquakes underneath Mount Edgecumbe. The numbers are in, and radar satellite data reveals a ground deformation around the volcano. Data was analyzed for the past 7.5 years, and since 2018, an uplift around Mt Edgecumbe has been constant. The peak activity, around the crater, has shown an average uplift of 3.4″ per year since 2018, and a total uplift of 10.6″.
With the data of the ground deformation, AVO has come to the conclusion that the swarm of earthquakes is due to the movement of magma below Mount Edgecumbe, and not due to tectonic activity.
Mount Edgecumbe, a 3200 foot high stratovolcano, lies 15 miles to the west of the community of Sitka. There is no volcanic monitoring system on Edgecumbe, but there is at Sitka. AVO plans to install instruments closer to the volcano in the near future.
The rising of magma under a volcano does not necessarily mean that an eruption is imminent. The deformation and earthquakes could cease at any time. If an eruption were to occur, warning signs such as increased rate of deformation, and an increase in the earthquake swarms, would give advance warning of an eruption.
The southern portion of Atka Island is older than the north, with some volcanic rock dating back 5 million years. The active northern part of the island once had one large cone, which was lost in a large eruption, and is now peppered with several smaller volcanos.
A volcanic complex can have several vents, and a widely varying composition of lava. Seismic activity within a complex can be difficult to pinpoint the source of the activity. Which vent is rumbling now? Some of those smaller vents have developed into stratovolcanoes.
Korovin Volcano has been very active in recent times, while Mount Kliuchef last erupted in 1812. The Atka Complex recently was elevated to a Level Yellow, due to seismic activity on the island. Interestingly, the swarm of activity is not near the known suspects, but several kilometers the the west and southwest, and approximately 10 miles from the community of Atka.
I had to share this shot from the Alaska Volcano Observatory and photographer Dave Ward. Great Sitkin has been at Level Orange and the lava dome has been growing since mid-July. According to AVO, the dome is now 100 meters across. What are the odds of having such a clear day out on Great Sitkin Island? Wonderful shot by Mr Ward.
Great Sitkin has been active most of the summer, although that lava dome build up has occurred in the last couple of weeks.
Both Pavlof and Semisopochnoi Volcanos are also at Level Orange. Pavlof is known to erupt with little to no warning, and it is showing elevated seismic activity, and at least one ash eruption. Explosions and elevated seismic activity on Semisopochnoi Island also continues. At least one ash eruption dissipated quickly, and sulfur dioxide emissions have been detected by satellite.
Cleveland Volcano rounds things out at a Level Yellow. Some seismic activity, but no reported ash eruptions.
Volcanos world-wide seem to be getting a bit anxious of late, and Alaska has three rumbling right now. The Great Sitkin volcano, which dominates the skyline of Great Sitkin Island, erupted on May 25. Lauren Flynn of the U.S. Fish & Wildlife Service captured this image as Great Sitkin erupted. Flynn was aboard the Research Vessel Tiglax at the time.
Great Sitkin Island was a fuel depot during WWII. The island lies between Adak and Atka, and is roughly 11 miles long by 10-1/2 miles wide. The Great Sitkin volcano rises to a height of 5710 feet above sea level.
Mount Veniaminof, which is located on the Alaska Peninsula, erupted last Thursday. The ash plume that exploded from the volcano did not reach 10,000 feet. Veniaminof last erupted in the fall of 2018.
Mount Veniaminof is a rather active stratovolcano, having erupted at least 14 times in the past 200 years. It is surrounded by a 25 square mile ice field. According to the National Park Service, the glacier is the only one known in North America with an active volcano at its center.
As of 7 March, Veniaminof continued to show an ash plume via satellite imagery. Mount Veniaminof rarely shows itself for the camera. The volcano is visible only one or two days a year, the rest of the time, Veniaminof is shrouded in clouds and fog.
Mount Veniaminof letting off some steam, 25 September 2018; Photo credit: AVO/Mari Peterson
Mount Veniaminof, the glacier covered volcano on the Alaska Peninsula, has been erupting since early September. The Alaska Volcano Observatory reports that lava is still flowing from the caldera this week. The volcano last erupted in 2013.
ESA Sentinel-2 image of Veniaminof, showing lava flow on the south flank of the volcano. Photo credit: AVO/USGS
Veniaminof sent a plume of ash, 13,000′ into the air in late November, but that action has come to a stop, at least for now.
Currently joining Veniaminof on AVO’s Orange Alert List, is the seemingly always active Mount Cleveland.