USGS increases alert level for volcano: ORANGE / WATCH


View of the eastern cone of Mount Cerberus in the Semisopochnoi caldera. Image: USGS / AVO / CA Neal

Scientists from the USGS and the Alaska Volcano Observatory (AVO) have raised the volcanic alert level of the Semisopochnoi volcano, showing a new period of unrest. According to the AVO, “a continuous volcanic quake (constant tremor) has started … and continues through the present time”. They add that satellite imagery has confirmed the presence of volcanic ash as well as a solid vapor plume and sulfur dioxide emissions. The Semisopochnoi volcano is monitored by satellite data, regional infrasound and lightning detection instruments.

Based on its location on the globe at 179 ° 46, East, Semisopochnoi is the most easterly land location in the United States and North America, located just 9.7 miles to the west of the 180th meridian of Alaska. Semisopochnoi is part of the Aleutian Islands, a chain of 14 large volcanic islands and 55 other smaller islands. These islands, with their 57 volcanoes, form the northernmost part of the Pacific Ring of Fire.

The Ring of Fire is an area around the edge of the Pacific Ocean where numerous volcanic eruptions and earthquakes occur. Caused by plate tectonics, the lithospheric plates under and around the Pacific Ocean move, collide and / or are destroyed, creating the seismic activity for which the Ring of Fire is famous.

The volcanoes in this part of the Ring of Fire are monitored by the Alaska Volcano Observatory (AVO), which is a joint program of the US Geological Investigation (USGS), the University of Alaska Fairbanks Geophysical Institute (UAFGI), and the Alaska State Division of Geological and Geophysical Studies (ADGGS). AVO is similar to the Hawaii Volcanoes Observatory (HVO) which monitors Hawaii’s three active volcanoes: Kilauea, Mauna Loa, and Hualalai. In the case of the AVO, they also monitor Cleveland, Semisopochnoi and Veniaminof. Alaska is however home to many volcanoes; there are over 130 volcanoes and volcanic fields that have been active over the past 2 million geologically young years. 50 have been active since the mid-1700s and AVO is studying them as well.

AVO is responsible for issuing aviation codes and alert levels for volcanic activity. Aviation codes are green, yellow, orange or red. When ground instrumentation is insufficient to establish that a volcano is at a typical background activity level, it is simply “unaffected.” While green signifies typical activity associated with a non-eruptive state, yellow signifies that a volcano is showing signs of elevated unrest above known background levels. When a volcano exhibits increased or increasing unrest with increased eruption potential, it turns orange. Finally, when an eruption is imminent with a significant emission of volcanic ash expected in the atmosphere or an eruption is in progress with a significant emission of volcanic ash in the atmosphere, the code turns red. Volcanic activity alert levels are normal, advisory, monitoring, or warning. As with aviation codes, if there is insufficient data, 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 shows signs of unrest elevated above background level, an advisory like the one currently in effect for Cleveland is issued. If a volcano is exhibiting increased or increasing unrest, a watch is issued while a warning is issued when a dangerous eruption is imminent.

For now, AVO maintains the code / alert level on “ORANGE / WATCH”.

AVO says additional ash plumes are possible, which could be problematic for transpacific jets flying near the volcano on their Asia-North America routes. Volcanic ash can create important damage to the jet engines passing through them or to the boat and car engines that ingest air filled with ash. Volcanic ash is hard and abrasive and can quickly cause significant wear and tear to various aircraft parts such as propellers, turbocharger blades, and even cockpit windows. Since volcanic ash particles have a low melting point, they can melt in the combustion chamber of a jet engine, creating a ceramic or glass glaze that then adheres to turbine blades, fuel nozzles. and the combustion chambers. A jet engine that ingests just a small amount of ash could suffer from complete engine failure. Overheating and engine failure are also possible in cars and trucks, as volcanic ash can seep into almost any opening in a vehicle. Ash is also very abrasive; ash trapped between the windshields and wiper blades will permanently scratch and mark the windshield glass, and windows are susceptible to scratching every time they are raised, lowered, and cleaned.

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