Ash emissions observed via webcam indicate an active eruption is in progress at the large stratovolcano; as such, the Aviation Color Code has been upgraded to ORANGE and the Alert Level to WATCH by the Alaska Volcano Observatory (AVO.)
AVO reports: “Clear web camera views of Pavlof Volcano this morning indicate episodic low-level ash emissions are occuring. Intermittent bursts of ash from the summit are producing diffuse ash clouds that are rising just above the summit and drifting southeast roughly 6 miles before dissipating.” The AVO adds that seismic and infrasound data indicate that activity at the volcano consists of occaisional small explosions and tremor.
Pavlof Volcano is a stratovolcano located on the southwestern end of the Alaskan Peninsula just under 600 miles southwest of Anchorage. The volcano is about 4.4 miles in diameter and has active vents on the north and east sides near the summit. According to USGS, the volcano has had more than 40 historic eruptions, making it one of the most consistently active volcanoes in the Aleutian Arc. The Aleutian Arc is on the Pacific Ring of Fire.
The Ring of Fire is a region around the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. Caused by plate tectonics, lithospheric plates under and around the Pacific Ocean move, collide, and/or are destroyed, creating the seismic activity the Ring of Fire is famous for.
Volcanoes in this portion of the Ring of Fire are monitored by the Alaska Volcano Observatory (AVO), which is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). The AVO is similar to the Hawaii Volcano Observatory (HVO) which monitors Hawaii’s three active volcanoes: Kilauea, Mauna Loa, and Hualalai. In the case of AVO, they monitor Cleveland, Semisopochnoi, and Veniaminof too. Alaska is home to many volcanoes, though; there are more than 130 volcanoes and volcanic fields which have been active within the geologically young last 2 million years. 50 have been active since the mid 1700s and AVO studies those too.
AVO is responsible for issuing Aviation Codes and Volcanic Activity Alert Levels. Aviation Codes are green, yellow, orange, or red. When ground-based instrumentation is insufficient to establish that a volcano is at a typical background level of activity, it is simply “unassigned.” While green means typical activity associated with a non-eruptive state, yellow means a volcano is exhibiting signs of elevated unrest above known background levels. When a volcano exhibits heightened or escalating unrest with the increased potential of eruption, it jumps to orange. Finally, when an eruption is imminent with significant emission of volcanic ash expected in the atmosphere or an eruption is underway with significant emission of volcanic ash into the atmosphere, the code becomes red. Volcanic Activity Alert levels are normal, advisory, watch, or warning. As with aviation codes, if data is insufficient, it is simply labeled as “unassigned.” When the volcano is at typical background activity in a non-eruptive state, it is considered normal. If the volcano exhibits signs of elevated unrest above background level, an advisory is issued. If a volcano exhibits heightened or escalating unrest, a watch is issued while a warning is issued when a hazardous eruption is imminent.
For now, the AVO is keeping the code / alert level to “ORANGE / WATCH” for Pavlof.
The AVO says additional explosions and ash plumes are possible, which could be problematic for trans-Pacific Jets that fly near the volcano on their Asia – North America routes. Volcanic ash can create significant harm to jet engines that fly through them or boat and automobile engines that ingest ash-filled air. Volcanic ash is hard and abrasive, and can quickly cause significant wear to various airplane parts such as propellers, turbo-compressor blades, and even cockpit windows. Because volcanic ash particles have a low melting point, it can melt in the combustion chamber of a jet engine, creating a ceramic or glass-like glaze that then sticks to turbine blades, fuel nozzles, and combustors. A jet engine that ingests just a small amount of ash could suffer from total engine failure. Overheating and engine failure is also possible in cars and trucks since volcanic ash can infiltrate nearly every opening in a vehicle. Ash is also very abrasive; ash caught between windshields and wiper blades will scratch and permanently mark the windshield glass, and windows are susceptible to scratching each time they are raised, lowered, and cleaned.
Pavlof is a stratovolcano, which is a conical volcano built up by many layers of hardened lava and eruption debris, also known as tephra. Unlike shield volcanoes, such as Hawaii’s Mauna Loa, stratovolcanoes are characterized by a steep profile with a summit crater and periodic episodes of explosive eruptions and effusive eruptions. Stratovolcanoes are more common than shield volcanoes and have a reputation for being very destructive. Vesuvius which catastrophically destroyed Pompeii and Herculaneum in AD 79, and Krakatoa in Indonesia, which killed thousands of people in 1883, are stratovolcanoes. Mount Saint Helens in Washington State is another example of a stratovolcano in the United States.
Pavlof is the second volcano in Alaska to “go Orange” this week. Semisopochnoi was just elevated to ORANGE / WATCH too, joining the Great Sitkin volcano. On July 23, USGS elevated the alert level and color code to ORANGE / WATCH for the Great Sitkin Volcano too.
Alaska also saw an impressive 8.2 earthquake on July 29, which prompted the issuance of many tsunami warnings and watches. Scientists are concerned that any explosive eruption at any of the volcanoes in the state could trigger an earthquake and/or tsunami threat for Alaska and beyond.