ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE U.S. Geological Survey Friday, May 27, 2016, 12:55 PM AKDT (Friday, May 27, 2016, 20:55 UTC)
CLEVELAND VOLCANO
(VNUM #311240)
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
Unrest continues at Cleveland Volcano. Seismicity remains low. The small lava dome first observed on May 18, 2016, enlarged slightly this week to about 60-meters (197 ft) in diameter. Dome growth appears to have paused or ceased as of Monday May 23. Weakly elevated surface temperatures were observed in mostly clear views by satellite on Wednesday and Thursday of this week which is consistent with the presence of the new lava dome. No other signs of eruptive activity have been observed in pressure sensor data or satellite imagery this week.
Cleveland volcano forms the western portion of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. The volcano is located about 75 km (45 mi) west of the community of Nikolski, and 1500 km (940 mi) southwest of Anchorage. The most recent significant period of eruption began in February, 2001 and produced 3 explosive events that generated ash clouds as high as 39,000 ft above sea level. The 2001 eruption also produced a lava flow and hot avalanche that reached the sea. Since then, Cleveland has been intermittently active producing small lava flows, often followed by explosions that generate small ash clouds generally below 20,000 ft above sea level. These explosions also launch debris onto the slopes of the cone producing hot pyroclastic avalanches and lahars that sometimes reach the coastline.
PAVLOF VOLCANO
(VNUM #312030)
55°25'2" N 161°53'37" W,
Summit Elevation 8261 ft (2518 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Unrest continues at Pavlof Volcano. Episodes of weak seismic tremor and associated small explosions were last observed on Saturday May 21. No ash emissions or evidence of elevated surface temperatures were detected in satellite and web camera data, indicating that activity was minor. Since then, seismicity has decreased and remains low. Clouds obscured views of the volcano by satellite and web camera and no signs of eruptive activity have been observed since May 21.
Pauses in activity of days to weeks are common during eruptive episodes of Pavlof Volcano. A return to eruptive activity remains possible and could occur with little or no warning. Thus, AVO will continue to monitor the volcano closely and will issue additional information as necessary.
Pavlof Volcano is a snow- and ice-covered stratovolcano located on the southwestern end of the Alaska Peninsula about 953 km (592 mi) southwest of Anchorage. The volcano is about 7 km (4.4 mi) in diameter and has active vents on the north and east sides close to the summit. With over 40 historic eruptions, it is one of the most consistently active volcanoes in the Aleutian arc. Eruptive activity is generally characterized by sporadic Strombolian lava fountaining continuing for a several-month period. Ash plumes as high as 49,000 ft ASL have been generated by past eruptions of Pavlof, and during the March 2016 eruption, ash plumes as high as 40,000 feet above sea level were generated and the ash was tracked in satellite data as distant as eastern Canada. The nearest community, Cold Bay, is located 60 km (37 miles) to the southwest of Pavlof.
ILIAMNA VOLCANO
(VNUM #313020)
60°1'55" N 153°5'30" W,
Summit Elevation 10016 ft (3053 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
Just before midnight on Saturday May 21, AVO detected seismic and pressure sensor signals associated with a large non-volcanic avalanche on the north flank of Iliamna Volcano. Avalanche events are somewhat common at this volcano. The seismic signals from the avalanche were observed on volcano monitoring networks throughout Cook Inlet and as distant as the Katmai region 250 km (155 miles) away. There is no indication of any volcanic activity associated with this avalanche.
Iliamna volcano is located on the western side of lower Cook Inlet in the Lake Clark National Park. Iliamna is a snow-covered stratovolcano which rises 10,020 feet above sea level. Although steam plumes occur on its eastern flanks, there has been no historic volcanic activity at Iliamna. Iliamna is located 225 km (140 miles) southwest of Anchorage and 113 km (70 miles) northwest of Homer.
OTHER ALASKA VOLCANOES
Other Alaska volcanoes show no signs of significant unrest: http://www.avo.alaska.edu/activity/
AVO scientists conduct daily checks of earthquake activity at all seismically-monitored volcanoes, examine web camera and satellite images for evidence of airborne ash and elevated surface temperatures, and consult other monitoring data as needed.
For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://www.avo.alaska.edu/color_codes.php
FOR MORE INFORMATION ON ALASKA VOLCANOES: http://www.avo.alaska.edu
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Jeff freymueller, Coordinating Scientist, UAFGI
jfreymueller@alaska.edu (907) 322-4085
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.