Aniakchak Developments!

 

The Alaska Volcano Observatory (AVO) announced that an increased rate of seismic activity at the volcano has been registered in mid-February, following the ongoing earthquake swarm from October 2022.

Ever since, quakes have become more intense and shallower at less than 5.6 miles (9 km) depth. Later on, in mid-February, earthquakes have continued to pick up in numbers per day including a maximum magnitude M 3.3 on 17 February. Transmissions of seismic records were disturbed due to a network outage in early March causing an inability to detect small earthquakes. However, the seismicity remains above background levels. The evolving activity was found in the strongest quake with a magnitude of 3.3 on 6 April.

Earthquakes and ground uplift (inflation) likely reflect magma injections and migration beneath Aniakchak caldera at depths between 2 to 2.5 miles (3 to 4 km). These shallow magma levels may indicate tell-tale sign of an impending eruption.

Therefore, a decision has been made to rise the Volcanic Alert Level to "Yellow".
In case of an eruption, pre-eruption volcanic tremor precursors are likely to appear hinting rising magma towards the surface. The main hazard represents volcanic ashfall and tephra deposits which may affect local communities, infrastructure and/or aviation safety, further ballistic impacts of volcanic bombs and pyroclastic flows within the caldera. During a large eruption, an interaction of snow and ice at the contact with hot lava flow and/or tephra may lead to snow melting on snow-covered slopes outside the caldera, resulting in lahars (mud flows). On the other hand, some magma intrusions don't result in an eruption and may remain trapped and rest beneath the surface for over the months or even years.


Scenarios
1 An eruption occurs that is similar to, or smaller than, the eruption of Aniakchak volcano that occurred in 1931. That eruption spanned six weeks, including strong explosive activity for the first ten days or so that produced measurable ashfall more than 124 miles (200 km) from the volcano. Later stages of the eruption produced smaller explosions and a lava flow in the caldera. Strong earthquakes were reported throughout.

2 No eruption occurs. The magma that has intruded beneath the caldera stalls and unrest declines.

3 This scenario is considered unlikely. An eruption much larger than 1931 occurs. While there have been rare larger eruptions in the geologic history of Aniakchak volcano, the amount of surface uplift currently observed does not suggest a body of magma is accumulating that is much larger than what erupted in 1931.

Source: Alaska Volcano Observatory volcano activity update 14 April 2023