Alaska's Shishaldin Volcano Alert Status Raised To Yellow

Another volcano in Alaska is being raised to Yellow Alert status by AVO after satellite images detected heightened thermal activity, and webcam observations showed steam emissions from the summit of Shishaldin Volcano. Shishaldin is one of many Alaskan stratovolcanoes lining the Aleutian Arc. It is one of the most symmetrical cone stratovolcanoes in the world, with only a cone vent to throw of fits perfect cone shape on the NW flank.

Image of Shishaldin Volcano from the Smithsonian GVP

The last activity of Shishaldin was reported in October of 2009, when AVO declared its last eruptive event to be over. The last event was a lava dome building event that did not turn into a full scale eruption. The current activity may be another such event, but as the previously emplaced dome could be unstable, collapse and subsequent explosions/ash emissions are possible. There are no significant human populations nearby Shishaldin, and thus very little risk to human life should an eruption occur, although if a significant eruption does take place, ash emission could divert flight patterns, as is common with Alaskan volcanoes. 

Image of last dome building event at Shishaldin Volcano from AVO

Avo has reported the current activity:

"The Alaska Volcano Observatory is raising the Aviation Color Code to YELLOW and the Alert Level to ADVISORY at Shishaldin Volcano based on satellite observations over the past day of increased surface temperatures in the summit crater, as well as increased emissions of steam observed yesterday in satellite and web camera images. These observations represent a departure from normal background activity at Shishaldin, but do not necessarily indicate that an eruption will occur. Similar levels of unrest were last noted during 2009, and did not result in an eruption. Shishaldin is monitored by a local seismic network, satellite data, web camera, telemetered geodetic network, and distant infrasound networks. Seismic monitoring of Shishaldin is significantly impaired due to equipment failures of seismic stations close to the volcano. We hope to be able to detect significant explosive activity (should it occur) using remaining functioning seismic stations in the region, satellite, and distant infrasound networks. AVO will continue to watch Shishaldin carefully for additional signs of increased unrest."

AVO is at this time hesitant to declare that an eruption is imminent. As always with Alaskan volcanoes (most of which are only monitored by seismographs, webcams, and satellites) it is difficult to adequately monitor them with the methods at hand, so typically AVO will wait for more direct evidence of an eruption before elevating the volcanoes alert status above Yellow (which is advisory, meaning aircraft are advised to use extra caution when approaching that airspace). But keep your eye on this volcano, as it has erupted over 20 times since record keeping began around 1824. Most eruptions have been quite minor or small (VEI 1-2), but it did have a couple of VEI 3 events in the late 1990's.

*****UPDATE 2/11/2014*****

AVO has released the following:

2014-02-11 11:02:42

"Unrest continues. Overnight, weakly elevated surface temperatures were seen satellite images. Partly clear web camera images from this morning show no activity. No anomalous seismicity observed in data from the one working station, though wind noise currently could be obscuring low levels of seismic activity."

2014-02-07 12:02:08 - Weekly Update

"Elevated unrest continues at Shishaldin. A possible volcanic cloud was observed this morning in satellite images beginning around 1545 UTC (6:45 AKST). This cloud may have resulted from a small explosive event at the volcano. The event was small enough that it was not detected by the one working seismic station near the volcano, but it appears to coincide with a signal recorded by a nearby tiltmeter. Satellite images suggest that the cloud may have reached as high as 25,000 ft asl, was ash poor, and short lived. There was no evidence of elevated surface temperatures observed in satellite data following this event, suggesting that it was primarily a gas event and very little to any hot material was produced and deposited on the flanks of the volcano. There have been no visible observations of the volcano since this event and AVO will continue to evaluate new data as it becomes available.Persistent elevated surface temperatures in the summit crater of Shishaldin have been observed during clear-weather intervals over the past week. Nothing unusual has been seen in seismicity from the nearest working station off the flanks of the volcano."

Iceland's Volcanoes Still Quiet

The land of Ice and Fire, it may be. But for the last few years now, it's been pretty much just Iceland. The last eruption to occur in Iceland took place after the now infamous Eyjafjallajökull eruption, from Grimsvötn (Grimsnes) volcano, which came and went without much fanfare. Since then, aside from some interesting quake activity, the restive continent has been nearly silent. So what gives?

Well, for one thing, volcanoes (contrary to popular belief) aren't on a schedule. Some very specific conditions need to occur for volcanoes to erupt. The eruption of Eyjafjallajökull in April of 2010 was preceded by around a decade of slow magma intrusion, and other volcanoes like Katla are buried under glaciers, which means it takes quite a bit of magma build up to break through the ice and produce an eruption. Katla had a suspected sub-glacial eruption after Eyjafjallajökull's Europe-stopping event, but this was inferred only due to glacial outburst flooding and chemical analysis.

Currently in Iceland, the ice is in full effect as Winter pokes along. It has been speculated that thick ice cover can suppress volcanic activity in Iceland (and maybe, perhaps, is suppressing volcanic activity in Greenland as well, although this has never been proven due to the thickness of the ice sheet), so some scientists suspect that quiet in Iceland could be due to this effect. When the ice retreats, an effect known as 'crustal rebound' is thought to occur, increasing the probability of an eruption, or at the very least, getting out of the way of an imminent one. But it has now been years since the last eruption and one can only wonder, which of these volcanoes will it be next?

Given what I am personally observing over there on seismographs, there seems to be only a couple 'likely' candidates for the near term. Askja volcano has been displaying some weak seismicity, and it is possible it had a slight ash and gas exhalation a couple years back, but this was never confirmed. Hekla volcano is always on everyone's watch list, but nothing unusual has been occurring there. That leaves really only a few more volcanoes over there that have much of a historical record of eruption, and none of them are acting particularly restless at the moment.

Hekla volcano has long been considered to be 'overdue' for a show, as it tends to be one of Iceland's most active. This volcano historically does not give a lot of warning before popping off, so it could indeed be primed for some action, and we simply wouldn't know. It is a complete waste of time with these volcanoes to actually predict WHEN they will go off, but it is certain that they will in the future. Time is the only thing that will tell. If anything, we could probably expect due to the ice cover, that the island may wait until Spring or Summer to show any activity as the ice recedes.

Icleand lies on a spreading fault, a tear in the earth's crust that is pulling the European plate away from the Atlantic plate, opening up fissures and channels for magma to rise up and become lava in an eruption. It is theorized that Iceland is part of a mantle plume system, much like Hawaii, that is positioned directly on this spreading fault, giving it a vast reservoir of magma, and possibly the largest mantle plume on Earth.

Dormant Peruvian Volcano El Misti Waking Up?

One of Peru's most well known volcanoes, El Misti, may be gearing up for some action. The Smithsonian GVP reports that El Misti has had some rather alarming seismic activity that could indicate magma intrusion at the volcano. El Misti does not have many historical eruptions under it's belt. The only confirmed one on record would be in the 15th century when it forced villagers to flee pyroclastic clouds.

The current seismic crisis is described by the GVP:

"Instituto Geofísico del Perú (IGP) reported that seismicity at El Misti increased during January, and a seismic swarm consisting of 119 volcano-tectonic events was detected during 14-15 January. Despite the increase, activity remained at a low level."

It is unclear exactly what they mean by 'activity remained at a low level', as all indications I can come across don't show any 'unusual' activity. The summit crater has nestled within it a fumerolic lava dome that displays heavy sulfur concentrations.

Image from Panoramio user 'dockx thierry' of summit lava dome and associated fumerolic activity.

An eruption of El Misti would likely include explosive eruption of the current lava dome, with associated pyroclastic flows descending its flanks (depending on which way the wind is blowing, it could descend any direction of the symmetrical volcano). There are several cities and towns in the shadow of the large stratovolcano, which could conceivably be at risk of ash fall and lava flow advancement, should the volcano enter into a more active phase.

As with all long-dormant volcanoes, only time will tell if the current seismicity will eventually result in an eruption. The majority of magma dike intrusions into volcanic systems do not immediately result in an eruption, and magma chambers can remain molten and pressurized for an indefinite amount of time. A good example of a fully primed, yet inactive volcano would be Mount Fuji (a very similar stratovolcano) in Japan. Scientists recently mentioned that Fuji's magma chamber is pressurized far higher than it was when it last erupted, leading some to suggest that only a minor earthquake along a bisecting fault line, could result in the triggering of an explosive eruption. 

Like Fuji, El Misti is a volcano on the Pacific Ring of Fire, a chain of volcanoes that spans the outline of the Pacific tectonic plate. It, like Fuji, also lies on a subduction zone, which causes eruptions to be far more explosive, rather than effusive like a hotspot volcano (Hawaii, Piton de la Fournaise, etc), possibly due to the immense amount of water and gases that accumulate on subduction generated magma.

Quake Activity Detected At Inskip Hill

About 20-25 miles WSW of Lassen Volcanic Center in Northern California lies a little known volcanic hill called Inskip. This is a Pleistocene volcanic cone complex which has had exactly no volcanic activity in historical time. Recently I have begun seeing some small quakes occur directly beneath it at a depth of about 3km, one of which occurred today at a magnitude of 2.2. This is probably nothing but it is always important to be vigilant when it comes to long dormant or presumably extinct volcanoes.

Location and magnitude of 2.2 quake under Inskip Hill, a presumably extinct volcano in Northern California near Lassen Volcanic National Park. 

While it is not at all probable that that these quakes of late are volcanic in nature, it is still possible. Inskip hill is not a well studied volcano. Indeed it was quite difficult to find any scientific or geologic information on the web, the only bit of info I found was at this link, where the volcano is described thusly:

"The hill is of volcanic origin and has numerous lava outcrops. It is part of a Plio-Pleistocene volcanic activity that began some miles to the east with the now vanished Mt. Maidu. From this cone issued first flows of basaltic andesite, followed by pyroxene andesite and dacite. Some 1.5 million years ago two enormous eruptions spewed forth rhyolite which covered some 180 square kilometers (70 square miles) to an average thickness of 152 meters (500 feet), followed by dacite avalanches which covered perhaps as third as great an area. The summit of Mt. Maidu collapsed, forming a caldera. Later came a series of basalt eruptions that built cinder cones with associated lava flows. Inskip Hill is one of these and dates to the mid or late Pleistocene. There are ice caves on the hill."

It is a bit puzzling as to why a well-preserved volcano such as this hasn't been more thoroughly studied, although the volcano does reside on private land, so I am assuming this is part of the reason.

For the past several weeks, I have seen some earthquakes pop off in this location, nearly directly under the summit of this volcano, or under its NE flank. While I am certain nobody is raising alarm bells over this (a magmatic intrusion would generate far more quakes, tremor, and probably GPS would detect ground swelling as CA is well monitored), it is still pretty interesting to speculate as to what could be going on down there. As some volcanoes have recently demonstrated (such as the abrupt and unexpected eruptions of Chaiten in Chile, and Nabro volcano in Eritrea), warnings are not always given when a volcanic system decides to reactivate.

Again, it is extremely doubtful that this is what is happening at Inskip, but perhaps blogging about these goings on might elicit some investigations, or perhaps some attention, by USGS (who as I recently found out, rather enjoy reading this blog!). In any case, I just thought this was an interesting opportunity to write about this very little known volcanic complex. I'm keeping my eyes peeled!

Japanese Volcano Asosan Has Small Eruption [video]

The volcano known as Asosan, one of Japan's most active volcanoes, has had a small eruption amid a period of heightened unrest. Nestled in the center of a 14+ mile wide Pleistocene caldera, the resurgent stratovolcano has produced phreatic and magmatic eruptions periodically since its first historically recorded eruption in 553 A.D. On the 14th (after the GVP report), Volcanodiscovery.com reported a magmatic eruption, and posted the below video.

The report from the Smithsonian GVP is as follows:

"On 27 December 2013 JMA raised the Alert Level for Aso to 2 (on a scale of 1-5) because volcanic tremor amplitude had been increasing since 20 December. However, on 2 January 2014 the amplitude rapidly decreased. Sulfur dioxide emissions were 1,200 tons per day during 2-9 January and 1,500 tons on 10 January. Volcanic tremor amplitude increased between 0800 and 1900 on 12 January. At 1215 on 13 January a very small eruption from Naka-dake Crater generated a grayish white plume that rose 600 m and drifted S, producing ashfall downwind."

The Smithsonain GVP describes Asosan:

"The 24-km-wide Aso caldera was formed during four major explosive eruptions from 300,000 to 90,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. The last of these, the Aso-4 eruption, produced more than 600 cu km of airfall tephra and pyroclastic-flow deposits. A group of 17 central cones was constructed in the middle of the caldera, one of which, Naka-dake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 AD. The Naka-dake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 AD. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic strombolian and phreatomagmatic activity. The summit crater of Naka-dake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations."

Eruptions of volcanoes in Japan and its associated island chains are common. Near the end of 2013, the volcano Nishino-shima began a submarine eruption that became a new island volcano off its coast. That volcano is still erupting, and growing the new island, which will likely be permanent, much like the 1960's eruption of Surtsey in Iceland. The volcano of Sakurajjima is also frequently active, and has many webcams on the web that you can watch.

Japan lies on the Pacific Ring of Fire, and lies on a subduction zone which has been responsible for many volcanic eruptions, large earthquakes, and tsunamis. In 2011, a 9.0 subduction quake cause massive amounts of damage, and an associated tsunami which has sparked a nuclear disaster in Fukushima which is being compared to Russia's Chernobyl disaster (although still not as severe).