Thursday, February 2, 2012

Alaska's Mount Iliamna May Be Erupting

Indications from USGS seismographs, and the corresponding Google Earth Plugin suggest that an eruption is either about to take place at Iliamna volcano in Alaska, or is already occurring. Earthquake plots from the last week until now seem to indicate rising and frequent tremor, with apparent explosions on the seismographs.

Iliamna is not near any population center, and Alaska is currently experiencing extremely cold weather (down to -48 C) which would hinder anyone or anything from making good direct observations of this remote volcano. It is probable that no observation via satellite, eyewitness, or airplane will be available for some time due to the harsh weather cycle this year. It is highly unlikely that during this period any visual observations could be made except by aircraft seeing an ash plume, which may or may not occur.

Below is a screenshot from Google Earth, with the USGS Real Time Overlay, where you can see quakes within a week (most magnitude 1.1-2.8) in yellow, and the more recent (and larger, up to mag 3.0) coded in orange, denoting a quake in the last 24 hours. These all occur at relatively shallow depths, and are directly beneath the summit, and along the flanks at lower depths. This indicates a rise in magma, and a possible eruption. These signals and the depths at which they are occurring can only mean magma intrusion, as this is a subduction zone, and most non volcanic quakes in the region happen at a much deeper depth (around 210km), not less than 1km. Subduction zones create an exteme amount of energy which heats the rock and creates magma plumes. The volcanoes of the Aleutian arc are very similar to the volcanoes of the Cascades and Indonesia in this respect.

AVO has stated "Since the middle of January 2012 there have been a sequence of earthquakes with several greater than magnitude 2. It is common to have earthquake swarms in the vicinity of Iliamna and the ongoing activity is being closely monitored by AVO seismologists.". They are aware of the current seismicity.

Image from Google Earth with USGS overlay. You can see the localization of the quakes here.

The seismographs from AVO seem to also indicate activity at the volcano. If it has not erupted already, there has CERTAINLY been a large intrusion of magma into its chamber, and will erupt soon.


                                     
Image of AVO seismograph for the last 24 hours. Clearly indicating possible dike intrusion.

Keep your eyes on Iliamna volcano. Especially the AVO seismographs. Unfortunately, this volcano does not have an active webcam to go with the seismograph, and people are very unlikely to be mounting an expedition to this volcano during the inclement weather that Alaska is experiencing right now. Indeed, the only report aside from this one (AVO would never speculate on their volcanoes without proof after all) would be from pilots. So for now, I'll say this. I absolutely suspect an eruption is either taking place at Iliamna currently (or already has), or it will happen very soon.

If there are any updates to this from any official source, I will update this post.

*****UPDATE*****

It appears via seismograph that constant harmonic tremor is now taking place at Iliamna volcano (see above seismograph image). After several large 3.0+ earthquakes, it does appear Iliamna may be erupting, or that there is further magma intrusion into the volcano. If AVO confirms this, it will be the first eruption of Iliamna since the 1950's.


2 comments:

  1. The seismic swarm under Mount Iliamna has resumed in the past few day, with a large number of earthquakes in the range between 1.0 and 3.1 being reported. Most of the earthquakes have been occurring in a rectangular shaped zone on the volcano's southeast flank that measures roughly 5 miles in length by 2 miles in width. The reported depth for most of these events has ranged between 3 and 7 miles, although some are being reported as surface events. The Alaska Volcano Observatory continues to report Mount Iliamna as a condition "green" volcano, which suggests that the experts there believe this activity is most likely related to dike emplacement. Since Mount Iliamna had a similar type of seismic swarn in 1996, it seems reasonable to suspect that is happening again. The weather in the region has been clear and beautiful the past few days, and thus far there are no reports of surface changes (i.e., ice/snow melt, increased glacial runoff or increased fumarolic activity) that typically precede eruptions of the Cook Inlet/Aleutian arc volcanoes.

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  2. Confirmed. AVO states "Since the middle of January 2012 there have been a sequence of earthquakes with several greater than magnitude 2. It is common to have earthquake swarms in the vicinity of Iliamna and the ongoing activity is being closely monitored by AVO seismologists."

    However AVO is a very cautious organization, and they are hopelessly underfunded in terms of expeditions. While the volcano does not yet show surface signs of the eruption, this is mostly due to the fact that dike intrusions rarely show any heat at the surface. The volcano Eyjafjallajökull in Iceland produced a random fissure eruption on its flank before the summit erupted, and there was no snow melt or gas emission preceding this event. The point being that volcanoes do not always show the signs we would think are typical, especially the ones in the much colder, glacier clad regions of the world.

    It would not surprise me in the very least if the volcano simply exploded without warning. One thing is certain, this is for sure a dike intrusion into the volcano. The swarms are simply too shallow, and too violent to be anything else but magma on the move.

    As far as the 1996 events, the current events seem to far outnumber the events in the late 90's. As far as I am aware, the new swarm has broken many records. This is somewhat similar to the precursors to the Mount St Helens event. Seismic swarms with little to no indicators on the surface of what is occurring below. As Iliamna has likely not erupted for 140-300 years, it is reasonable to assume that surface activity would be at a minimum since fumeroles and fissures have long collapsed or have been sealed by erosion and ice.

    I for one can't wait to see what happens, and if I am correct! If I'm correct that it's about to erupt, I think AVO should send me some good Alaskan beer!

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