Alaska's Mt Spurr Has Glacial Outburst Flood

Alaska's mt Spurr volcano, which last erupted in 1992, depositing ash on nearby Anchorage, AK, had a glacier outburst flood (or jökullhlaup if you like the Icelandic tongue twister) which lasted about 45 minutes after a period of weak, shallow quakes. This is pretty common in a lot of glacier-clad volcanoes, and especially in Iceland where geothermal activity routinely melts water under a glacier's surface, which results in a 'burst' of water escaping, causing sudden floods.

This does not mean the Spurr is gearing up for an eruption, as this could merely be normal behavior for the volcano (as also occurred in 1993, with no subsequent eruption), however this is one of the signs that volcanologists look for as a potential warning. If for example, the volcano began to do this rather regularly, there might be cause for concern. For now AVO has not raised the alert level, and probably will not unless the event repeats itself.

AVO's report is below:

"SPURR VOLCANO
61°17'56" N 152°15'14" W, Summit Elevation 11070 ft (3374 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

Early on the morning of June 25 a minor increase in seismicity occurred at Mount Spurr. The character of the seismicity recorded was consistent with the seismic energy generated by an energetic flow of water, possibly a glacier outburst flood on the lower south flank of Mount Spurr. The flow was a single event lasting about 45 minutes and was associated with several discrete shallow earthquakes up to magnitude 1 in size. Within hours of the onset, seismic levels declined to near background and no additional flowage signals were observed. Visitors to the area were advised to use caution if in or around the drainages on the south flank of Mount Spurr, especially those draining Kidazgeni glacier, and the Chakachatna River east of Kidazgeni Creek. A similar flowage event occurred on June 29, 1993.

Mount Spurr volcano is an ice- and snow-covered stratovolcano located on the west side of Cook Inlet approximately 120 km (75 mi) west of Anchorage. The only known historical eruptions occurred in 1953 and 1992 from the Crater Peak flank vent located 3.5 km (2 mi) south of the summit of Mount Spurr.

These eruptions were brief, explosive, and produced columns of ash that rose up to 20 km (65,000 ft) above sea level and deposited several mm of ash in south-central Alaska, including approximately 6 mm of ash on Anchorage in 1953. The last known eruption from the summit of Mount Spurr was more than 5,000 years ago. Primary hazards during future eruptions include far-traveled ash clouds, ash fall, pyroclastic flows, and lahars or mudflows that could inundate drainages all sides of the volcano, but primarily on the south and east flanks."

Antarctic Volcano, Siple Shows Signs Of Activity

You don't normally hear much from the land way, way down under given the very low human presence in Antarctica, but today the GVP reports that the Antarctic stratovolcano Siple is showing geothermal signs. This was confirmed via satellite imagery which observed vapor plumes and temperature variations at the summit of the massive volcano. If confirmed, this would be the first credible evidence on record for historical activity at the volcano. While the volcano has been studied and determined to be Holocene of age, it has not had any confirmed activity since it has been discovered, and a potassium-argon date is unavailable for its apparently most recent eruption.

The GVP describes this volcano as follows:

"Mount Siple is a youthful-looking shield volcano that forms an island along the Pacific Ocean coast of Antarctica's Marie Byrd Land. The massive 1800 cu km volcano is truncated by a 4-5 km summit caldera and is ringed by tuff cones at sea level. Its lack of dissection in a coastal area more susceptible to erosion than inland Antarctic volcanoes, and the existence of a satellite cone too young to date by the Potassium-Argon method, suggest a possible Holocene age (LeMasurier and Thomson 1990). The location of Mount Siple on published maps is 26 km NE of the actual location. A possible eruption cloud observed on satellite images on September 18 and October 4, 1988 was considered to result from atmospheric effects after low-level aerial observations revealed no evidence of recent eruptions (Smithsonian Scientific Event Alert Network Bulletin)."

The current statement from the GVP as of today's weekly report:

"Infrared imagery from the Metop satellite showed a possible rising steam plume from the area of Siple on 20 June. The imagery, as interpreted by Mark Drapes, indicated that the volcano was about -22 degrees Celsius, about 6 degrees warmer that the surrounding landscape, and the base of the plume was about -55 degrees Celsius."

While this report is not definitive proof that the volcano is erupting or preparing to erupt, it could indicate some unrest. The only evidence whatsoever so far that it is an active volcano is the 6 degrees Celsius differential from the surrounding area, and what appears to be steam from a satellite view. Until scientists or an expedition can have visual proof from the ground, this could end up being something like the 1988 'episode' that ended up to be an error. No worries however, as the volcano exists in one of the most remote places on earth, with not a human being in sight for thousands of miles.

El Hierro Not Finished Yet?

The volcanic island of El Hierro, part of Spain's Canary Islands, is showing increased signs that it is again gearing up for some activity. According to IGN and Earthquake-report.com, there were over 104 magnitude 2 or above quakes at the island yesterday alone. This is on par with the amount of quakes that preceded the previous and all but over eruption of the submarine volcano off the coast of the town of La Restinga. The below YouTube Video is an animation of the quakes in sequence and magnitude.

The activity currently being experienced is almost certainly related to further dike intrusion underneath the volcano, and a likely precursor to future activity on the island. The Spanish government had previously declared the eruption over, despite occasional underwater bursts from the small submarine cone that was constructed over around a year. Harmonic tremor had all but disappeared, leaving only a weak signal. But the volcano never truly stopped its activity. Degassing and other emissions are still ongoing, and those who know are still certain that El Hierro is far from done.

The location of the current swarm of quakes suggests that next time El Hierro erupts, it might not be underwater this time. So far, Pevolca, INVOLCAN, and IGN have all been mum on the quakes, saying only that they are monitoring the situation in real time. It is of some concern that the small cone which has ceased erupting is probably blocked form doing so again, so the question now is where can/will the magma release? If it can't go the same direction, it will go another.

At last glance, the quakes are still ongoing, with some above magnitude 3.0. If they rise to 4.0, 5.0, or higher, the island may very well have another situation on their hands. I will return to active monitoring of this volcano, as it appears things are changing quickly. The below photo is a real time (for today) seismic graph. It's starting to look pretty familiar.

Continuous Seismicity in Katla Volcano

Earthquake swarms this time of year are no stranger to Kalta volcano in Iceland, however the current swarm may be cause for at least a minor amount of apprehension. Since late last month, quakes have been occurring regularly within Katla's summit caldera underneath the famed Mýrdalsjökull glacier. Katla regularly has rumblings of this nature, but the latest tremors have also been accompanied by ice melt, which is a cause for concern-- or at least a cause for residents to begin getting their "eruption kits" ready to go.

Katla has not had a major eruption in centuries in recent memory (Jon Frimann pointed out eruptions in 1860 and 1918 int he comments below, however most people were not alive back then) , however in late 2011, it did produce a minor eruption which resulted in a jökullhlaup, or 'glacier outburst flood', in which a significant amount of the glacier covering the caldera was melted, creating a massive sub-glacial lake, that suddenly burst from the outer walls of the glacier to produce a flood laden with liquefied ash, boulders, and chunks of ice that demolished a bridge and damaged roadways and farms on its rampage to the coast.

Katla's 2011 eruption was considered extremely minor for this volcano, which has been responsible in the past for some of the largest eruptions in modern historical time from the Atlantic island. In addition, some scientists claim that the volcano should have erupted shortly after its neighbor, Eyjafjallajökull, did in 2010, but this so far has not occurred.

As the seismicity has been ongoing for over a month now within the caldera, I would certainly say at this point that the volcano is growing restless. Granted, no harmonic tremor has so far been recorded, at least nothing out of the norm... these could be merely crustal adjustments to the volcano due to the shrinking icecap in the summer, and adjustments due to the small discharge of magma to the surface last year compensating for the gap in the magma chamber... one can definitely not be sure as there is currently no employed technology on Katla capable of imaging the magma chamber. 

The volcano, given the fact that thus far there has been no clear signal of magma injection, is by no means in a phase of imminent eruption however. While seismicity remains high, there are still none of the typical signals that the volcano is gearing up for a show. There have been instances when long dormant volcanoes have suddenly blown with little to no warning, and perhaps Katla might be one of them, but it is impossible to tell. As there were no scientific instruments available hundreds of years ago to give us an indication of the behavior of the volcano, we have no record of any precursors from a Katla eruption.

More Earthquakes at Katla Volcano in Iceland

The rumbling at Katla volcano continues, as a month has passed since the current 'swarm' (if you can really call it that) has continued. As the ice retreats above Katla's caldera, so too does pressure decrease on the volcano, thus making it much easier for gases, and heated water to bubble up and produce small quakes. As far as the Icelandic Meteorological Office is concerned, these quakes do not appear to be entirely volcanically related.

The quakes occurring are most likely (not certainly) related to crustal adjustments, and the reduction of the amount of ice on the summit. While this does actually increase the possibility slightly that an eruption could occur, the only reason for this is the pressure decrease. It would still take a fresh (and large) injection of magma into the volcanoes chamber in order to trigger an eruption, and given that there is thus far very little if any change in the normal harmonic tremor, it does not appear that these quakes have any reason to concern Iceland or Europe... at least not yet.

While Katla is widely believed to be "overdue" for an eruption, it is always important to note that even though sometimes there appear to be patterns in volcanic activity, this is really not the case. Looking only at statistical data, it is impossible to really say when a volcano will erupt. Katla will erupt again in the future, but when is a question that cannot be answered yet. I will continue to monitor Katla and if anything new occurs, I will post on it. But right now, I'm going to assume that the volcano is simply 'stretching out' and enjoying the summer, nothing more, nothing less.