Friday, March 9, 2012

Alaska's Cleveland Volcano Has An Explosion, Iliamna Rumbles Away

Alaska's volcanic activity is picking up. Mount Cleveland was reported by multiple news sources and AVO as having had an explosive event on Wednesday, although the cloud is reported to be far less in height than the 20,000 meters it would take to institute a no-fly zone. AVO stated "A small, short duration explosion was detected from Cleveland Volcano on distant seismic stations and infrasound arrays. The time of the explosion was approximately 4:05 UTC March 8 (7:05 PM March 7, AKST.) Weather cloud conditions prevented the detection of an eruption cloud in satellite images or visual observation of the summit. This explosion was similar to recent small events that occurred in December 2011 and produced small ash clouds that dissipated quickly and did not affect air traffic. At this time, no further activity has been detected."

And as Cleveland volcano slowly plods along with what seems to be akin to a slow motion, low explosive eruption, a volcano I have mentioned in a previous post, Iliamna, is showing more signs of dike intrusion. Heightened seismicity including very shallow quakes under the restive volcano, which has no recorded history of eruptions during human habitation in Alaska, is causing AVO to suspect what I have said in the past, that Iliamna is waking up, and is preparing to erupt. The last radiocarbon dates for any eruption at Illiamna are thought to be 140-300 years ago. A record number of seismic events (for Illiamna) is occurring, and AVO scientists are planning a fly by to check for any visual signs of a change in activity. They will be checking for steaming, fumeroles, melting ice, etc.

Today alone, Illiamna has had over 40 quakes, some of them not-so-small, with the largest being a 3.2 magnitude beneath the summit, at a depth of only 2.0km, closely followed by a 3.1 quake at a shallower depth of 1.2km. It is my humble opinion that Illiamna is indeed ready to erupt, and this will occur either this month, or this year. We will wait and see, but so far I have been right about this volcano, and as far as I know, I was the first to report on its unrest aside from AVO noticing the tremor waves (I could not find anything or any other news that was posted before this article). Maybe I'm on to something!

Current seismic tremor at Iliamna Volcano, from AVO website.

In any case, the amount of quakes today alone make me almost think an eruption is already occurring. If it isn't it certainly might very soon, and we have very little idea as to how this volcano will erupt, given that it has never been witnessed in eruption (the only info we have is forensic). The picture below shows the current (last 24 hours) swarm of quakes, while the quakes in Yellow have occurred within the week. 

Image from Google Earth with USGS real-time quake overlay.

Iliamna is a stratovolcano, common for the US's Pacific Ring Of Fire volcanoes, and is most likely capable, like most of its neighbors, of large explosive events. An eruption at Iliamna will most likely cause some disruption to air travel, as well as ashfall on nearby towns, however the immediate area surrounding the volcano is not populated by any permanent towns. This volcano will likely not be able to directly kill anyone, thankfully. Time will tell on this, but it is looking more and more like an eruption at Iliamna is imminent.

As of now, AVO has NOT raised the alert level for Iliamna, however if I were them I would at least consider at this point raising the alert level to "Yellow" (watch). It would be a tragedy if this volcano were to erupt as an airplane is flying over, much like the incident in the 1980's when Mount Redoubt suddenly blew and nearly caused a fatal crash.

The Smithsonian GVP says this about Iliamna:

"Iliamna is a prominent, 3053-m-high glacier-covered stratovolcano in Lake Clark National Park on the western side of Cook Inlet, about 225 km SW of Anchorage. Its flat-topped summit is flanked on the south, along a 5-km-long ridge, by the prominent North and South Twin Peaks, satellitic lava dome complexes. The Johnson Glacier dome complex lies on the NE flank. Steep headwalls on the southern and eastern flanks expose an inaccessible cross-section of the volcano. Major glaciers radiate from the summit, and valleys below the summit contain debris-avalanche and lahar deposits. Only a few major Holocene explosive eruptions have occurred from the deeply dissected volcano, which lacks a distinct crater. Most of the reports of historical eruptions may represent plumes from vigorous fumaroles east and SE of the summit, which are often mistaken for eruption columns (Miller et al., 1998). Eruptions producing pyroclastic flows have been dated at as recent as about 300 and 140 years ago (into the historical period), and elevated seismicity accompanying dike emplacement beneath the volcano was recorded in 1996."

I will probably post an entirely separate article should Iliamna decide to erupt.

*****UPDATE 3/11/2012*****

AVO has raised the alert level at Iliamna to Yellow. They posted the following statement:

"Over the past three months the earthquake rate at Iliamna Volcano has steadily increased and now exceeds normal background levels. Although it is not certain that this sustained increase in earthquake activity represents the movement of magma at depth, it is a significant change and AVO has increased the Alert Level to Advisory and the Aviation Color Code to Yellow. The current activity does not mean an eruption is imminent or certain. A similarly energetic episode of seismic unrest from September 1996 to February 1997 was likely related to the intrusion of new magma at depth, but an eruption did not occur."

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