Saturday, June 30, 2012

El Hierro Island Uplifted Several Centimeters

The earthquake swarms are continuing at El Hierro, months after the submarine eruption ended, and has caused new inflation of the island. Uplift and displacement of up to 5cm has now occurred since the beginning of the month, suggesting that deep underground, new magma is indeed being injected to the deep magma reservoir under the island. INVOLCAN scientists, according to Earthquake-report.com are staying on the island for the next 30 days, at their own expense, despite the Spanish government keeping the volcano at alert level 'green'. It seems the scientific community disagrees.

While today's activity is a bit lower than the past couple of days, the previous activity at the volcano (for those that were following it) appeared to be random and have some high and low periods of seismicity. If the same deep magma mechanism is in place, and injection is still occurring, you can expect bursts of strong activity accompanied by randomized weaker activity.

The seismicity is even in the same place as when the island built up for the last eruption. It is not far fetched at this point to assume that an eruption could be a couple of months, or even weeks away, but so far these quakes have been deep, and no new CO2 emission increases or other signs of impending volcanic activity have so far been observed. Right now all that is certain is that about 20-15km below the island, magma is re-inflating the chamber. If this continues for some time, this might indicate an eruption is about to take place again in the future. If it ceases, the magma may simply stir a while and cool slowly.

El Hierro is once again a place to watch on the list of active volcanoes.

*****UPDATE 7/2/2012******

This morning there was another hour long period of heightened seismicity, producing several quakes that were felt by residents. The new center of activity is at the NW tip of the island, partially on and partially off the coast. So far, the alert level remains the same. GPS graphs showed slight subsidence taking place BEFORE the quakes started (we are waiting for the post swarm data from Earthquake-report.com, which is one of the only blogging sites on the 'net with boots on the ground).

Earthquake activity is still much stronger than in past weeks, but currently it does not appear to be getting much stronger, and if anything, it might be getting weaker. It is still far too soon to tell whether or not the seismicity portends a future eruption of the island.

UPDATE:

Earthquake activity has returned and has now been sustained for up to 6 hours. Many quakes are above 3.0.

Friday, June 29, 2012

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."


Wednesday, June 27, 2012

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.

Monday, June 25, 2012

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.




Friday, June 22, 2012

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.


Friday, June 15, 2012

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.

Friday, June 8, 2012

El Hierro Activity Ramping Up Again

El Hierro, the volcano in the Canary Islands, may not be quite done yet (as was suspected by a great many following the behavior of this volcano). Although officially the government had lowered the volcanic threat alert level down to "Green", many volcanologists and volcano enthusiasts (including myself) were skeptical about the government's stance on the volcano. This week nearly 20+ earthquakes occurred at depth and some more shallow, as a science vessel captured images of a submarine ash and gas emission at "Bob", the submarine cone of El Hierro.

Other indications point to renewed or at least intermittent activity of the volcano, and much to the chagrin of the authors at Earthquake-report.com, the Spanish government seems to be covering it up, or at least attempting to obscure observations from the rest of the world and scientific community. For what reasons, nobody knows, but I suspect it is another wrong-headed attempt to get tourists to come back to the island.

While the El Hierro submarine vent has been relatively quiet these past couple of months, it has remained in a state of degassing, and the recent emission points to the possibility that the eruption could easily resume at any time. The amount of magma erupted is still far smaller than the volume of the actual magma chamber, and most likely much smaller than the amount of new magma that was injected into the chamber. Due to these facts, it is likely that the El Hierro island could see a longer period of eruptive activity in the future (this could be a precursor event to a more 'traditional' eruption above land, but so far there have been no records of serious GPS deformation, or increased CO2 emission on land).

The volcano caused quite a stir in the scientific community when the eruption was preceded by many thousands of small quakes. The island itself had not had an eruption since the 1700's, which was poorly documented internationally (locally, there is a wealth of knowledge and history), and most people had thought the Island to be dormant. That changed when a presumed eruption started taking place off the coast of the fishing village of La Restinga. The eruption was spotted when dead fish started washing ashore, and a large 'stain' on the oceans surface manifested. This was followed by what is known as a Serretyan eruption, which produced 'lava balloons' - bubbles of gas filled lava that would float to the oceans surface, and produce a fiery burst when the lava cracked and exposed superheated gas to oxygen. The lava rocks would then fall back to the ocean floor, building the underwater cinder cone further.

This continued for some months, and eventually dwindled down to a degassing phase. Many people had hoped/thought that the volcano would eventually create a brand new mini Canary Island, in what is called a Surtseyan eruption (where a submarine volcano breaks the water's surface to crate either an ephemeral island, much like what occurs regularly in the Marianas island/volcano chain, or a more permanent island like the recent eruption of Jebel Zubair in Yemen). It would have been a spectacular site for those on the island, and those that were watching the eruption webcam before the Spanish government shut it down (apparently running a webcam is really expensive! Yeah right...).

So I will again follow the goings on at La Restinga like I did before the eruption ended to bring you updates as they happen. This is a fun and suspenseful volcano for me to write about because it is such an unusual eruption, and it's occurring on an Island that didn't have much historical eruptive history. I always enjoy a good surprise. I'm not so sure the residents at La Restinga do however, as apparently they are beginning to loathe the attention that their volcano is getting, both from the reporters at El Hierro, and their own government.

Thursday, June 7, 2012

Large Quake Swarm At Katla Volcano

Katla volcano is again showing increased seismicity and unrest, as the Icelandic cold season comes to a close. Today there were over 25 small quakes within the caldera, with most of the quakes in the range of 1.0-2.0 in magnitude. Katla volcano has long been thought to be overdue for an eruption. As the train of thought goes, as goes Eyjafjallajökull, so goes Katla shortly thereafter. This has proven to be somewhat of a guesstimate,  as Katla has refused to blow even after the 2010 eruption of Eyjafjallajökull which caused massive disruption to transportation in Europe.

Katla has been having near continuous quakes under its caldera for decades. While lately it may seem that Katla is preparing to blow, it should be noted that many quake swarms occur in the area regularly. These quakes are probably (almost definitely) related to magma intrusion into the caldera, it remains a phenomena that is unlikely to produce a massive eruption.

Katla volcano is covered in a thick glacier, and as such has somewhat of a natural eruption suppression system in place, given that the ice sheets are so thick. The volcano does frequently have magma intrusion, but most of the time, the ice mitigates this and simply causes glacier outburst floods (jökullhlaups) to occur, typically not resulting in explosions. However when Katla builds enough pressure, the result can be disastrous.

The current activity at Katla volcano is not a surprise, nor unexpected, and probably will not result in a whole lot of action. The media such as the BBC, or the Telegraph, will most likely blow this out of proportion. It is important to note that Katla frequently has quake swarms, dike intrusions, etc, that do not immediately manifest themselves as volcanic activity. However there is always a risk that an eruption could occur as a result of these magmatic intrusions into the volcanic system.

As always, time will tell if this will result in anything. A good 90% of the time, quake swarms are merely a distant precursor to a future eruption and nothing more. Sustained swarms are the ones to watch for, and given the past few weeks, I'm fairly certain that this is simply normal behavior for the volcano. Nonetheless, it is a noteworthy swarm, and you can watch the near real-time activity at http://en.vedur.is.

Wednesday, June 6, 2012

Quiet month

There isn't a whole lot going on in the volcano world this month. The usual suspects are still erupting (you can see them at http://volcano.si.edu), and the rest of the world for now is pretty quiet. I have not been posting blogs lately as I am still in the midst of setting up my new computer system and importing my volcano databases, earthquake monitoring programs, and other neat plugins that show what the Earth is up to.

Rest assured as anything of particular interest occurs, I will certainly post about it.

I would however like to take an opportunity to say thank you to my readers, and those who are supporting this blog. It takes a lot of energy, and contemplation to write a blog that is worthy of your time, so to those that take the time to read when I post an article, I would like to say thank you.

The lull in volcanic activity this month is always a good thing for those that live around volcanoes, except of course for communities that depend on volcano tourism. Most of the volcanoes erupting currently are volcanoes that are either in a continuous state of eruption, or are frequently in a state of unrest. There have not been many reports lately of any volcanoes that have erupted with any amount of surprise.

Cheers to that!