USGS raises volcanic alert level


View of the Davidof volcano captured in 2005. Image: CA Neal / AVO / USGS

Due to the possibility of volcanic unrest, the United States Geological Survey (USGS) and its Alaska Volcano Observatory (AVO) have increased the warning level and color code to YELLOW / ADVISORY at Davidof Volcano in Alaska.

Home to many tufted puffins and horned puffins, Davidof Island is believed to be part of a circular complex of island remains of an ancient two-cone volcano that was destroyed in a catastrophic eruption at the end of the Tertiary period. The Tertiary Period began around 66 million years ago with a mass extinction event that killed the dinosaurs and ended when the Ice Ages of the Quaternary Period began around 2.6 million years ago. million years ago. Nicknamed the “Krakatoa of the Aleutians,” the Davidof Island volcano is located in the west-central Aleutians.

According to AVO, in the past three days, a swarm of earthquakes has struck around the Davidof volcano. The largest earthquake to date occurred this morning at around 10:45 a.m. local time and had a magnitude of 4.2. “This swarm may be associated with volcanic unrest or it could also be due to regional tectonic activity,” AVO said in a statement.

The Davidof volcano located along the “Ring of Fire” which 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 US Geological program. Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI) and the State of Alaska Division of Geological and Geophysical Surveys (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 elevated unrest above background level, an advisory 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.

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