Printer friendly version
LEVEL OF CONCERN COLOR CODE: ORANGE
LAST LEVEL OF CONCERN: ORANGE
Based on continuing seismicity, a low-level eruption continues a Pavlof Volcano on the Alaska Peninsula. During the past week, periods of increased seismicity are interpreted to correlate with episodic eruption of ash and bombs several hundred to perhaps 1,000 feet above the summit of the cone. Analysis of satellite imagery over the past 24 hours detected no ash cloud in the vicinity of the volcano. Visual and satellite observations of the volcano have been hampered by poor weather and the remoteness of the volcano, however pilot reports yesterday also confirmed no significant ash venting above the cloud tops at 10,000 feet.
Since the late 1700's, nearly 40 separate eruptions of Pavlof Volcano are known to have occurred, making Pavlof one of the most active volcanoes in Alaska. Recent eruptions have been characterized by an early explosive event that can propel ash to an altitude of over 10 km (33,000 feet) above sea level. The eruptions then proceed as intermittent, low-level Strombolian activity with ejection of fluid lava spatter and small amount of ash and incandescent bombs to heights of usually less than 1000 feet above the cone. Spatter-fed lava flows and ash-rich mudflows can also result from the accumulation of hot material on the steep flanks of the volcano. This kind of low-level activity could continue for many months,
punctuated by occasional more explosive events.
Pavlof is located 600 miles southwest of Anchorage on the Alaska Peninsula. The nearest towns to the volcano are Cold Bay (37 mi), King Cove (30 mi), Sand Point (60 mi), and Nelson Lagoon (50 mi). These towns could expect light ash fall depending on wind direction and level of eruptive activity. Mudflows and some flooding could occur in the Cathedral River valley north of the volcano. The hazard to aircraft from airborne ash may be considerable if a large explosive event occurs, however during the more characteristic low-level activity currently in progress, this hazard is minor.
AVO maintains a six-station seismic network near the volcano. Until further notice, we are maintaining 24-hour staffing at the Observatory to monitor the situation.
AVO received a pilot report late yesterday of a small ash plume above Amukta Volcano in the Central Aleutian Islands. An Alaska Airlines pilot noted black and gray clouds rising about 1,000 feet above the summit crater during overflights on both September 17 and 18. The ash plumes extended 10 miles south over the Pacific Ocean before dissipating.
Amukta is a poorly known, seismically unmonitored, and uninhabited island stratovolcano located about 230 miles east of Adak Island. It has erupted at least 5 times since 1760, most recently in 1987.