New Info On Yellowstone Suggests "Super Eruption" Was Two Smaller Eruptions

Yellowstone volcano has long thought to have had a large super eruption over 2 million years ago, but new evidence is suggesting that while 2 million years ago Yellowstone DID erupt with a VEI 7 or 8 eruption, it was not as big as once thought, and was followed 6,000 years later by a smaller eruption. The result was an ash layer that appeared to be one layer but was actually two. This suggests that Yellowstone is NOT as powerful as once thought, but is more active.

The study revealed that the Island Park Caldera is actually much more active than previously thought, and the new information might assist scientists in better predicting an eruption from Yellowstone, given that the timeline has now changed. The last magmatic eruption in the Yellowstone caldera was some 70,000 years ago, and an episode of phreatic eruptions that created a 5km wide crater (now Yellowstone Lake). 

Scientists were using a new "Rock Clock" method to determine the ages of ash and rock layers within the Huckleberry Ridge, and were surprised at the data they found. The data suggests that Yellowstone's explosive eruptions were around 12 percent weaker than previously thought, but smaller eruptions are actually more numerous. The last eruptive activity of any kind in Yellowstone occurred somewhere around 1350BC (give or take around 200 years), and was limited to hydrothermal eruptions.

Knowing when, or how, Yellowstone might erupt in the future is one of volcanology's biggest challenges, given the impact an eruption from Yellowstone might have. But the new data seems to shrink the idea that Yellowstone is capable of a world-ending eruption (one thing I highly disagree with most scientists about is that any event on earth is capable of wiping out 'all life'... life did not simply get wiped out and reappear on the planet, there are always survivors). Indeed, the new data seems to suggest that Yellowstone is not capable of "blotting out the sun worldwide", but is still a very dangerous volcano to anyone within about 100KM.

This is good news for anyone who was worried that Yellowstone could be a 'world ender', and probably bad news for anyone who wants to scare people into doomsday nonsense for the tabloids. An eruption from Yellowstone today would likely be much weaker than previous eruptions, given that as far as anyone knows, no new magma has been introduced into the Yellowstone system for a very long time. Scientists theorize that the current magma chamber consists of partially cooled magma known as 'crystal mush', and any eruption would likely result from water flashing into steam when it seeps into hot rock (a phreatic eruption). These types of eruptions are short lived, and very rarely pose a threat outside of 1km, but anything is possible.

In any case, this new info will definitely be helpful to understanding further the history and potential of the Yellowstone caldera.

Island of Fogo Is Having Volcanic Tremor

The island of Fogo looks like something out of a sci fi fantasy movie. A massive island inlayed by a large caldera, with a spire-like volcanic cone in the center that looms high over the tropical landscape. Below the peak of Fogo (Pico do Fogo) lies a paved over, barren landscape, surprisingly home to houses and facilities built atop fresh lava flows. Fogo was one of the first volcanoes that fascinated me, given its striking appearance and remote location. To visit this volcano, for me, would be quite a sight.

Fogo is not a very well-known volcano, but it is capable of some serious eruptions. Indeed the original caldera forming event likely created tsunamis and landslides that would have hit the neighboring islands, and maybe even the African West Coast. The island itself is dotted with cinder cones young and old on its flanks, suggesting a very active life cycle as a volcano. Now, the volcano is getting seismic equipment installed on it, and already, results are coming in pointing to volcanic tremor, and small volcanic earthquakes. Fogo is waking up.  (or was it ever truly asleep?).

Fogo's last eruption occurred in 1995, when a small cinder cone was erupted on the WSW flank of the Fogo peak. This eruption started off as a fissure, and gradually built a cone, and produced slow moving pahoehoe lava flows that pooled at the base of the mountain.

Picture of the 1995 eruption of Fogo, from Smithsonian Global Volcanism Program website. Photo by Dick Moore, 1995 (U.S. Geological Survey)

The Smithsonian GVP Characterizes Fogo here:

"The massive 9-km-wide, horseshoe-shaped Cha caldera truncates the summit of Fogo stratovolcano, the most prominent in the Cape Verde islands. An ash plume (center) rises from the western flank of a steep-sided central cone, Pico, that rises more than 1 km above the caldera floor to form the 2829 m high point of the island. Pico, which is capped by a 500-m-wide, 150-m-deep summit crater, was apparently in almost continuous activity from the time of Portuguese settlement in 1500 AD until about 1760."

An eruption of Fogo today would likely be characterized by another small cinder cone building event, or possibly a larger more explosive event from the summit cone (which has not recently erupted historically speaking), which could be capable of strombolian type, or Hawaiian type eruptions. Flank eruptions on the West side of Fogo were considered to be Holocene, but most eruptions have occurred on the East side of the caldera rim recently. The West side of the island is heavily vegetated and is probably not at risk.

The Portuguese islands of the Cape Verde chain are all volcanoes, or have been volcanoes at one point in time or another (some are very old). Installation of more monitoring equipment is exciting news for some of us who long for a global volcanic monitoring network, and certainly for the scientists who will be poring over reams of seismic data. Every year, volcano monitoring gets better and better, and disasters and deaths are able to be more easily averted due to good early warning systems. It is my thought that within 10-20 years of today, we will actually be able to routinely scan a volcanoes magma reserves to determine whether an eruption is imminent, and when it might occur. The new muon-based mapping technology developed in Japan is a major step forward, and is currently being tested on volcanoes such as Vesuvius, and Fuji. 

If anything new develops on Fogo, you'll read about it here!

Shallow Quake Swarm at Joshua Tree East Of Palm Springs

There is absolutely nothing, and no information on this on the web, so I thought I might bring it into the light for scrutiny. There is a continuing quake swarm occurring in Joshua Tree National Park, about 35 miles East of Palm Springs, CA that is beginning to look quite intriguing. The range of depth is from 8km to less than 1km, and about 2 quakes are occurring every hour. The strongest quakes were two mag 3.5 tremblors that were lightly felt in Palm Springs and surrounding towns.

The area is definitely part of the Rio Grande rift, a series of spreading faults that resemble "stretch marks" on the Western USA's topography. This rift, much like the African Rift Valley (although nowhere near as active volcanically) is home to a great many volcanic features. This particular area is parallel to the San Andreas fault line, the most active fault line in the USA.

The swarm is concentrated below an ancient volcanic mountain, and has been very consistent in its locations. All quakes are occurring within a mile of each other. This does look a bit like a deep magma dike intrusion, but it is definitely still way to soon to tell what is going on. Dike intrusions into the crust happen all the time, and most times they never result in any surface volcanic activity.

A Google Earth Snapshot with USGS real-time quake overlay showing the location and number of quakes in the swarm. The largest quake occurred yesterday and was a mag. 3.5, with a matching 3.5 quake occurring today (4/4/2012).

While this probably is a magma intrusion into the crust, there are other possibilities such as these being a precursor (foreshock) to a larger quake in the future, or a very small tectonic slippage. In any case, this swarm is intriguing not just because of its location, but because of the number of quakes occurring within the area. As this is occurring along the San Andreas fault however, it is very hard to tell whether or not this is purely tectonic, or if there is an intrusion taking place.

As this is, to my knowledge, the only article about these quakes so far, I will withhold further speculation about what is going on here until (or if) the USGS comments on the quakes, or if they become newsworthy. It is simply impossible to tell from available data whether or not these events will be significant, or insignificant, but as always I will keep an eye on these interesting occurrences, and post updates if anything changes. For now, keep your eyes peeled East of Palm Springs (and I would avoid going spelunking out there any time soon!).

*****UPDATE 4/9/12*****

The quake swarm is continuing with now more than 50 quakes striking the region. The swarm is very much beginning to look like a dike intrusion, at least on the Google Earth USGS plugin. It is quite similar to the precursors at El Hierro, deep quakes, numerous, and rising in depth. Still, nobody is reporting on this, so I am at the mercy of my own assumptions, which I will keep quiet for now, but this is definitely an area to keep an eye on for a while, at least until USGS takes notice. If anything further develops, I will update this post again.

Earthquake Swarm and Possible Dike Intrusion at Krísuvík Volcano in Iceland

There is not a whole lot going on in the world in respect to new eruptions or volcanoes at this moment, however Iceland is always fascinating to watch. Today there was a swarm of quakes just SW of the Kleifarvatn lake, just south of the epicenter of Krísuvík volcano. The quakes were shallow, weak, and numerous, but the area is highly active, much like most of Iceland. Most of the quakes registered below a 1.0 magnitude, but were clearly seen on the many Icelandic seismic sensors. The are is home to many thermal vents, as well as hot springs, fumeroles, and fissures.

The last known eruption of Krísuvík volcano was in the 14th century (the 1500's). A few eruptions have taken place at this location after Iceland was settled, but nothing in recent times. It is probable that this swarm will not lead to an eruption any time soon, but Iceland sits on a spreading fault, so it is not a matter of if, but when this volcano will erupt again.

There are several volcanoes in Iceland that are expected to erupt at least within the next 10 years. Those are Katla, Askja, Grimsvötn (or Grimsfjall, Grimsnes), Hekla, and the Reykjanes Ridge, all of which show heightened seismic and thermal activity. However for most of these volcanoes, it is normal to display some kind of activity, and no eruption for any of these, save probably Katla and Hekla, are certain.

Icelands last major eruptions were from Eyjafjallajökull, and Grimsvötn. The Grimsvötn eruption, while spectacular to watch, was nowhere near as big a deal as the Eyjafjallajökull eruption which caused widespread economic damage due to flights to and from Europe being grounded for weeks because of the ash cloud it produced. The ash from Grimsvötn is much more coarse and larger grained than the very fine and powdery ash produced by the Eyjafjallajökull eruption, and thus fell to the earth quickly and did not get picked up by the jet stream.

The activity at Krísuvík can be attributed to a few causes. For one, Iceland is one of the worlds largest users of hydrothermal/geothermal energy, and regularly injects water into hot rocks to produce steam. This does sometimes cause swarms of quakes to occur, and it is rather hard to tell whether or not this could be related, but as the quakes happened on an active spreading fault, I suspect this is not the case, rather a small magma dike intrusion probably occurred.

Around the world most dormant volcanoes are sleeping or slowly rumbling away. Mt Etna did display some nice activity this weekend, but other than Etna's fireworks show, most active volcanoes showed relatively little activity during the month. Not good for us volcano bloggers out there to tell a story, but hey, the Earth does what it wants on its own time with little concern for my Google money! Hopefully this post is at least a good diversion! I'll post more as it occurs!

New Info On Bolivian Volcano Uturuncu Indicates Uplift Is New

The recently "awakened" supervolcano in Bolivia, Uturuncu, may have actually awakened just recently, according to new data. The data suggests that the volcano began re-inflating quite recently. In fact, a report on VolcanoDiscovery.com suggests that the uplift began as recently as 1992, according to sediment uplift data. This suggests that not only is Uturuncu awakening, it suggests that Uturuncu is quickly building up its massive magma reservoir and may actually lead to activity in the area... and at the worst case, a caldera forming super eruption.

Uturuncu has never erupted in historical time. Indeed data suggests it has not erupted for over 200,000 or more years, making it an enigma. The current uplift of approximately 1-2cm per year over a 70km wide radius from the central volcano, suggests mathematically a magma intrusion of approximately 1 cubic meter per second, from a source approximately 14km in depth, filling a much shallower 3km deep magma chamber. To keep things in perspective, this is the same approximate distance of the Yellowstone caldera's magma chamber depth.

The difference between Yellowstone and Uturuncu however is vast. Yellowstone displays far more fumerolic and hydrothermal activity, however as far as we know, it has always done so in our history. Uturuncu has been quiet during the same period of time, until now. On average, 2.6 earthquakes per day are recorded at the volcano, sometimes spiking to more than 14 quakes per day. Harmonic tremor is present at Uturuncu, unlike Yellowstone, which geologists say has not had much magma intrusion or inflation. Indeed, scientists theorize that a lot of the uplift and subsidence at the Yellowstone caldera is related to gas and water, not magma.

Uturuncu getting a fresh injection of magma after such a long time is something new to scientists. Most volcanoes that are dormant for this long tend not to erupt again... or so we thought. Many volcanoes with long periods of dormancy-- some we thought were extinct-- have recently 'activated' and erupted with incredible force. Nabro volcano in Africa, and Chaiten volcano in Chile, were both thought to be long dormant, or completely extinct. All it took for these volcanoes to "wake up" were some rather large quakes and a quick injection of fresh magma. Chaiten and Nabro volcano are still active.

This new data on Uturuncu is both fascinating and terrifying, although scientists caution not to worry or start planning your doomsday bunker just yet-- it can take thousands of years for Uturuncu's magma chamber to inflate to the point where it will actually erupt... PLENTY of time to plan for a disaster (and who knows, in 1,000+ years we might have technology that can "deflate" a volcano and prevent it from erupting catastrophically... purely in the sci-fi realm at the moment, but I don't put it past us to innovate our way out of a super eruption in the future).

There is always, however, the possibility that the volcano has simply tapped into a vast source, and will erupt without warning. It has happened to much smaller volcanoes, and rest assured it can happen to any volcano. There is truthfully no point in worrying about a super eruption from Uturuncu. Surface activity is nominal, with the same fumeroles and hot springs active that have been for thousands of years. No new surface activity like steaming, fissure cracks, etc have been observed at the site, so for now at least, there is nothing to worry about in the near-future.

Uturuncu is surrounded by the worlds largest collection of supervolcanic calderas. Millions of years ago, Bolivia was host to some of the worlds most violent eruptions, and Uturuncu is just ONE large volcano out of hundreds in the area. The area is poorly studied, so it would not surprise me in the least to learn there are several volcanoes out there that are inflating without our knowledge. Pure speculation though, and I do try to stay away from that. In any case, this data will be used to refine our understanding of supervolcanoes, and give scientists and opportunity to track the inflation of what was thought to be a long-dead mountain.

AVO Lowers Alert For Cleveland Volcano To "Yellow"

The slowly erupting stratovolcano in Alaska, Mt. Cleveland, has been lowered to level "Yellow/Advisory" with AVO geologists stating "No further explosions have been detected at Cleveland since March 13, and we have no evidence that lava-dome growth has renewed since then. Therefore, we are lowering the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY."

Mt. Cleveland had been experiencing slow lava dome growth for the better part of a year, with a couple of collapses and small explosions, but nothing in the range of some of its past activities. Cleveland volcano has in the past erupted quite violently creating large plumes of ash some 30,000 feet high, but this episode was slow, effusive, and really not a huge deal.

The island itself is uninhabited, and far from any populated areas. It is however the only volcano of the Aleutian arc with a fatality (one) on its record, from an eruption in 1944. Mostly the volcano has annoyingly deposited ash  on nearby towns during large eruptions, or caused air traffic diversions.

The other volcano showing signs of unrest in Alaska is Mt. Iliamna which has undergone a series of magmatic quakes, thought to be related to dike intrusion. A recent expedition by AVO scientists to this volcano has revealed an increase in gas emissions (SO2, and CO2), and vigorous steaming/fumerole action. AVOstates that this does not mean an eruption is imminent and they saw no signs of rockfall, or avalanches in the area. However, they did seem to note some slight deformation in a glacier, but they were unable to attribute that solely to the volcano.

Government Officials Declare El Hierro Eruption Over... When It's Not

Apparently under public pressure to declare the resort island of El Hierro "open for business", Government officials in Spain/Canary Islands have declared the alert level at El Hierro be lowered to "green" (the level before the eruption). This occurs as INVOLCAN conducted an R.O.V. mission to the crater, and discovered that yes, in fact, the volcano is still very much erupting, although the characteristics of the eruption has changed. While there is no vigorous "jacuzzi" on the surface, below the water a lot is still going on.

The eruption is very much like the submarine eruptions produced by Loihi on the southern end of the Big Island of Hawaii. Pillow lavas are being extruded onto the sea floor, and continue to do so.

So was this declaration of "green" a politically motivated, and non scientific maneuver? You betcha. I don't think there would be one actual scientist studying this volcano that would say the eruption has ended. If that were true... well obviously lava would not be flowing, now would it?

So the eruption actually continues at this time. The type of eruption this has ended up as is not a Surtseyan eruption, as many people thought might occur, rather the eruption type is called an "Serretyan" type eruption. Earthquake-report.com has a lot more info on this, but I thought I'd share their great image they published on what characterizes a Serretyan eruption.

Descriptive image of a Serretyan eruption, from Earthquake-report.com

El Hierro is a difficult volcano to analyze and monitor as it has turned out to be very unique in its eruption characteristics. Many thought a pyroclastic cone would develop on the island, or that an eruption would ensue in the El Golfo bay (probably because it is shaped like a caldera, even though its just a massive collapse scarp), which actually still has the potential to happen, but it ended up being a very benign submarine eruption that never reached the water's surface. While not an exciting eruption to watch, the concept of this volcano is pretty intriguing, and of great scientific interest, as this volcano is displaying some mechanics that we don't often get to witness.

In any case, if anything interesting happens at El Hierro, I'll be sure to post about it! I simply wanted to share this with the readers to notify that the eruption is still going on, despite what governments may say!

AVO Sends Team To Mt. Iliamna To Check Gas/Temps [UPDATED]

AVO scientists have sent a team of geologists on a fly-by mission to Mt. Iliamna, Alaska's restive volcano that has been showing signs of activity since January. The apparently successful mission to go to the volcano to check gas levels and temperatures on the summit fumeroles has produced results, and AVO is expected to release their findings today on their website (http://avo.alaska.edu).

Mt. Iliamna has been experiencing heightened levels of seismicity for some time, but recently in January there were some rather intense quake swarms, at very shallow depths (some swarms were less than 1km underneath the surface), with some quakes registering up to magnitude 3.7. AVO has subsequently raised the alert level to "Yellow"(watch), and has actually directed one of their webcams to watch the volcano visually (below picture).

Live webcam snapshot from AVO.alaska.edu

Iliamna does not have a record of historical eruptions, however AVO and GVP state that it's last eruption was approximately 140-200 years ago. Active fumeroles exist at the summit, and the last activity in 1996 was similar to the current level of activity.The 1996 quake swarms were also thought to be magma dike intrusion, much like today's swarms. AVO scientists stress that this does NOT mean there will be an eruption, however I would wager that with several dike intrusions, the magma will try to find some way to the surface. In my opinion, a minor eruption is very likely at Iliamna in the coming months or years.

It is anyone's guess as to what characteristics an eruption at Iliamna would take on. It is a stratovolcano, and part of a subduction zone, so like most Aleutian and Alaskan volcanoes, it would likely be an explosive event followed by dome growth and thick lava effusion. For now, AVO is monitoring the volcano, and so am I!

*****UPDATE 3/20/2012*****

AVO has completed their initial survey of Iliamna volcano and released the following news:

"Seismicity at Iliamna Volcano remains above background. Data from Saturday's gas and observation flight indicate that the volcano is emitting elevated levels of sulfur dioxide and carbon dioxide, consistent with a magmatic source. It is not know, however, if this is a newly intruded magma, or whether new pathways for gas from preexisting magma have caused the increased gas flux. The amount of gas being emitted is broadly similar to levels seen in 1996-1997, when a likely magmatic intrusion but no eruption occurred at the volcano.

Observers on the flight saw vigorous and plentiful fumaroles (gas vents) at the volcano's summit, consistent with the elevated gas emissions. No obvious signs of recent rockfall, large areas of newly exposed bedrock, or unusual disturbance of the glacial ice were observed. Some deformation of the ice at the headwall of the Red Glacier on the east side of the summit was seen, but it is not clear this is related to the current volcanic unrest; avalanching of the glacier is common on this very steep area and was last seen in 2008."

So it does appear at this time that activity has at least increased visually, indicating rising temperatures from deep below. Iliamna is officially a volcano to keep an eye on!

Katla Volcano Has Another Quake Swarm

Katla volcano in Iceland is having another quake swarm today, during what some say is supposed to be a quiet time geologically for Iceland, during the harsh Winter months. Seismicity is elevated today at the Mýrdalsjökull glacier, with some quakes even occurring at the neighboring Eyjafjallajökull volcano. Eleven tremblors struck within the Katla caldera within the last 24 hours. As I write this, the swarm is ongoing. Most of the quakes except for two were below 2.0 in magnitude, with the largest being a 2.5. Many smaller >1.0 quakes occurred.

This again is probable dike intrusion into Katla, which has seen elevated seismicity and geothermal activity since its very small eruptive event last year (which produced a glacier outburst flood, and caused minor damage to bridges and roads). 

Image from Iceland Met Office showing today's quakes at Katla/Mýrdalsjökull 

Katla has been seismically active for months, with most scientists expecting an eruption soon.When is impossible to say, however this will likely be larger than last time due to the amount of magma intruded into the system. Swarms have occurred at the volcano at least a few times in any given month since June of 2011, but so far has not resulted in a large eruptive event like its neighbor Eyjafjallajökull, who's eruption in April 2010 produced a large ash cloud, carried by the jet stream, and stranded millions of travelers in Europe as airliners were grounded due to ash concerns.

Europeans fear a repeat of this event should Katla erupt, however it is anyone's guess whether an ash cloud from Katla would even follow the same pattern. It is entirely possible that the ash cloud going go East, and give the United States East Coast a taste of the headaches that Europeans suffered. Or the ash could simply blow South, into the ocean, harming no one. In any case, Katla rumbles on, gearing up for its inevitable show. 

Italy's Mt Etna Has 4th Eruption of 2012

Mt.Etna has been stealing the show lately with spectacular eruptions (called paroxysms) that have been very frequent this year. Yesterday Etna erupted producing lava fountains, and light ashfall. This is the 4th paroxysmal event of 2012, and part of Etna's regular pattern of eruptions.

Etna is (arguably) the world's most active volcano, aside from possibly Kilauea in Hawaii (although Kilauea has only been erupting continuously since 1983, Etna has been active for far longer), and is host to frequent lava flows and explosive activity. Etna has seen more activity lately, and the webcam is rather fun to watch, especially if you like to watch great lava shows.

While the eruptions do not pose a threat to any towns or population centers, Etna is a large and sprawling shield volcano, and has erupted far outside the summit previously, producing pyroclastic cinder cones, fissures, and more. The potential for an eruption on its lower flanks is an ever present threat, however this has not happened in a very long time.

Lamongan Volcano In Indonesia Showing Signs of Brewing Eruption

Lamongan Volcano in Indonesia is showing signs that it may soon erupt. The normal background seismicity of a few quakes a month has skyrocketed to more than 150 events per week, prompting the Indonesian government to raise the alert level to 2 out of 4. A 1km radial exclusion zone from the summit is now in place as authorities attempt to prepare for an eruption from this volcano.

Lamongan was last active during the end of the 19th century and has been relatively quiet ever since.The landscape surrounding the volcano is dotted with numerous large maars (explosion craters created by groundwater coming into contact with hot magma or partially molten rock), cinder cones, and fissure vents.While not particularly active during human habitation, the evidence is all around for an active history spanning hundreds of thousands of years.

Greece's Santorini Volcano Inflating

Santorini, Greece's famed caldera volcano is inflating according to GPS instruments and volcanologists. The inflation has also been accompanied by increased seismicity, and volcanologists state that the magma chamber has grown by about 500 million cubic feet. Scientists are quick however to point out that this does not mean an eruption of Santorini is imminent, and even if there were to be an eruption, the conditions for a caldera-forming  eruption that wiped out the original Santorini island and the Minoan civilization are not present.

An eruption at Santorini however could be disastrous for the Greek country, which is struggling financially and is barely getting back to solvency.

Any eruption at Santorini would likely be further building of its central island cone, or submarine in nature, but could easily end up as a powerful explosive event which could devastate the harbors and anchorages within the caldera, and would definitely be disruptive. The last eruption of Santorini was in 1950, and produced a small lava dome and flow on the middle island of Nea Kameni. The previous eruption in 1866 produced explosive eruptions which did result in some injuries to scientists observing the eruption (rather closely and dangerously by today's standards).

There is no chance of an eruption on the scale of the famed Minoan eruption, due to the fact that it takes a supervolcanic or caldera forming eruption hundreds of thousands of years to really recharge and create the conditions for such an event.While an eruption at Santorini would be hugely disruptive to residents and tourists alike, the most likely scenario is that it will simply end up being scientifically fascinating, and benign. Time will tell however, and the world will continue to watch.

6.9 Magnitude Quake Strikes Off Japan Coast

A 6.9 magnitude earthquake struck off the coast of Honshu, Japan near the location of last year's deadly quake and tsunami. Six large aftershocks have occurred so far in at or near the epicenter ranging from 6.1 down to 4.6.  More quakes shook the Tokyo region later in the day. The quakes off the coast of Honshu generated a small 8-inch high tsunami. No damage was reported.

This series of quakes (while rather common in the region now) comes almost exactly one year (plus a few days) after the devastating magnitude 9.0 magnitude quake.The 9.0 mega-quake damaged the Fukushima nuclear plant resulting in a meltdown and widespread radiation which has devastated a large portion of Japan and has made the land uninhabitable. Further damage was visited on Japan by a 30-40ft high tsunami wave that destroyed large portions of Japans coastal cities.

The subducting plate is now in nearly continuous motion since that event, with large quakes being a fairly regular and almost daily occurrence. it is regular for magnitude 5.0 and up quakes to hit the region along the subducting plate.

Japanese scientists are also closely watching the restive Mt.Fuji for further signs of unrest following a series of quakes in the area, and recent (very unclear) reports of "a new crater" on the NE side of Fuji (however this was NEVER confirmed), as well as reports of new fumeroles.NONE of these reports are confirmed, and translation from Japanese to English via Google translate is worthless. Volcano-report.com has however picked up the story, and I also wrote a blog earlier last month about this report, gathering all the information that I could (which wasn't much).

In any case, expect Japan to continue to be a hotbed of earthquake and volcanic activity for quite some time.

Japan's Sakurajima Volcano Has Violent Explosion

The Sakurajima volcano in Japan had it's most violent explosion since 2009, Japanese media and other sources are reporting. Japan's most active volcano in recent years, it had completed the year 2011 with the highest number of explosions on record since people began counting. Activity at the volcano shows no signs of slowing down.

Sakurajima is a complex stratovolcano with many vents, only a couple of the vents have been active in historical time. the volcanic complex is constructed within the Aira caldera, a massive caldera that formed about 22,000 years ago. Sakurajima is a post caldera cone, and has seen much activity throughout human history.

The Smithsonian GVP's summary of Sakurajima is as follows:

"Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76."

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."

It Is Official: El Hierro Eruption Has Ended

INVOLCAN has declared the eruption of El Hierro to be over, and the alert status of the island has been lowered from Red to Yellow. The village of La Restinga can finally open its doors to tourists again, however maritime activity is still restricted due to probable degassing, and swimming in the water is still off limits pending a chemical analysis of the water to determine its safety. Sea life has already begun to repopulate the area, a good sign for the fisherman of the village.

The eruption at El Hierro was preceded by a lengthy period of volcanic earthquakes, which were used to size up the magma chamber. The island was on Yellow alert for a long time, before a "jacuzzi" was spotted in the ocean, and harmonic tremor increased. The eruption of the underwater cone "Bob" started as an underwater fissure eruption, eventually resulting in a cone building event. Several collapses of the main vent stalled the eruption, which stopped and started several times. On occasion, floating "Lava Balloons", or gaseous bubbles encased in molten rock, would float to the surface and emit steam, and sometimes flames once the bubbles burst and allowed oxygen to interact with the heat. This however was as exciting as the eruption got.

For about a month now, the eruption has all but ceased entirely. Harmonic tremor has been at low to background levels, and there has been very little if any surface activity since February. This is what led the scientists to declare the eruption over, although their maintaining of alert level Yellow does indeed reflect what many of us know, that activity can resume at any time, and caution is still in order. Some volcanoes have a small cone building event as a precursor to a larger eruption, something that is certainly not out of the question.

Current uplift sensors show the island to be stable, which could mean that the magma reservoir has not deflated, and merely extruded the lava to form "Bob" because it was the easiest path to the surface. Quakes are still ongoing at El Hierro in an area not near "Bob", and it is still worth keeping an eye on the island. El Hierro and the Canaries have been compared to the Hawaiian islands in regards to the type of eruptions it produces. The theory goes that El Hierro, like Hawaii, is a hotspot type volcano. These are highly unpredictable as we have no way of imaging or monitoring the mantle plumes that are though to be responsible for hotspot volcanoes.

It is my guess that activity will pause now for probably months, and either slow subsidence will take place, or activity will resume in another location. It is now a game of wait and see. In any case, I doubt that the residents of El Hierro will ever forget now that they are living on an active volcano, and will be ever mindful of the power that lies beneath their feet.

Supervolcanoes And Why You Shouldn't Worry So Much

It's a pretty quiet week in volcano world (at least until I can get my paws onto the latest GVP report), so I thought I might dabble in the realm of supervolcanoes today, since they are such a hot topic, and very misunderstood.

There has been plenty of hype in the news media surrounding so-called supervolcanoes like Yellowstone, Toba, Rotorua, Uturuncu, and the like. Media outlets looking for a sensational and fascinating story seem to fixate on the apocalyptic scenarios of a Yellowstone eruption, or an eruption so devastating that it wipes out humanity as we know it. While there are supervolcanoes in our midst, and some like Yellowstone that are still seething and breathing, a true supervolcanic eruption has never occurred in the span of recent human history, and probably will not for a very long time.

Yellowstone had its last truly catastrophic eruption some 600,000+ years ago. Journalists and some researchers point out that Yellowstone has a major caldera type eruption around every 600,000 years, and some say the volcano is overdue. But this again assumes that volcanoes actually have a schedule, and conform to our time lines. This of course is absurd. Volcanoes erupt simply when the conditions are met for an eruption, and Yellowstone is a far ways away from anything major. At the very worst, we'd probably see a small phreatic (water explosion) eruption, or a minor cone building event, but even this is far fetched at this point in time.

The ONLY supervolcanic eruption in human history occurred approximately 75,000 years ago in Indonesia. A volcano named Toba erupted, punching a gigantic caldera into the earth's surface, creating a mini ice age, and reducing the population of humans worldwide to around 5,000 individuals. This has been proven from many angles like ice-core samples that show an immense amount of sulphur dioxide and tephra, as well as DNS analysis of humans pointing to a genetic bottleneck around that time.

The next largest eruptions in recorded human history were the eruptions of Tambora in the 19th century, the eruption of Krakatoa (now Anak Krakatau, 'child of Krakatoa), and the eruptions of Mt. St. Helens, and Pinatubo. These eruptions were all on a scale of VEI 6 to VEI 4. Far from the supervolcanic force of a VEI 7 eruption which is required to be classified as a supervolcanic event.

There are no supervolcanoes currently displaying the characteristics of an imminent eruption. The requirements for such an eruption are extremely rare, and complex. First, the magma chamber has to be massive, fully charged, and pressurized, and then it needs an injection of fresh magma from the mantle. Surface observations would include heightened fumerolic and geyser activity, ground uplift and swift deformation, accompanied by multiple explosive events, culminating in the emptying of the magma chamber, and subsequent collapse of a massive caldera. There are NO volcanoes that currently display any of these characteristics... not even Yellowstone or Uturuncu.

Events like these are extremely rare, and require all of the above conditions to occur. Given that the earth has already suffered so many volcanic eruptions, and several supervolcanic events, one might wonder if the Earth still has the magma required to make one happen. It does, and supervolcanic events will happen again... but the likelihood of one happening in your lifetime is so infinitesimally small, they're hardly worth the calculation. In fact, you have a much better chance of seeing a meteor strike the earth, or a supernova in space than you are to see a supervolcano erupt.

Supervolcanoes are terrifying, fascinating, and worrisome for governments to prepare for... but one has to ask... given that we've never had a super eruption in our living history, why would we lose sleep over something that is so unlikely to occur? Most of the worry and hype can be blamed on the "2012'ers", Hollywood, or just plain old Yellow Journalism. Some can be blamed on conspiracy theories, or doomsayers. But truly, it is human nature to be on guard about any threat to our existence, and while the threat exists, we will always pay attention. I however will never lose any sleep worrying about Yellowstone. 

El Hierro Eruption Officially Over?

Reports from earthquake-report.com are saying that INVOLCAN will officially declare the eruption at El Hierro to be over today, possibly lowering the overall alert level to "green" and allowing the village of La Restinga to slowly return to normalcy. Tremor for the past few weeks has been at a minimum, with little to no changes, save the very slight increases and decreases in amplitude, and occasional small earthquakes. For now it seems, the eruption of "Bob", the submarine volcano that ALMOST made it to the surface of the water, is over.

This however does not mean that activity on the island as a whole is finished. Indeed, deformation is still occurring, and earthquakes are getting shallower at other locations around the island. So, while the village of La Restinga may be able to breathe a sigh of relief that "Bob" has gone to sleep, the rest of the island as a whole is still on pins and needles. The last eruption of El Hierro occurred in the 18th century, and lasted two years.

While many volcano enthusiasts and scientists alike were watching El Hierro with anticipation of being able to see a well-documented Surtseyan type eruption (which ended up not happening), the island chain of Jebel Zubair in Yemen pulled a fast one on us and had an island-producing eruption behind everyone's back. Quite frustrating if you were hoping to witness the actual birth of an island from start to finish. It's really too bad that the Zubair group of volcanoes isn't really monitored that well, or we might have gotten our wish.

All things said and done, the ending of the El Hierro eruption, and the lowering of the alert level for La Restinga will likely come as a relief to islanders, as they have been hurt economically by the closure of the fishing port, and the hotels/cafe's which were evacuated during the heightened alert. While the local and Spanish governments might have used the eruption as a tourist draw, like they do on Hawaii or Iceland, the local media hyped the story and scared lots of people and tourists from the island. Only bloggers, and locals were actually reporting on this eruption objectively (or close to objectively), which has given me much more respect for bloggers and freelance journalism.

In any case, my best wishes to the residents of El Hierro, and hopes that if activity does resume, or start in another area, it will be as mellow as the eruption of "Bob", and merely be an interesting, not violent, occurrence. Time will tell if the island has gone back to sleep, but as far as the local government and the scientists at INVOLCAN are concerned, it's time to consider the eruption over... but a word of caution, I'm pretty sure volcanoes don't have to follow government law or statements... we're living on their schedule, not the other way around.

Even though the eruption has "officially" ceased, there will be some remnant activity at the volcano, such as degassing, and occasional structural adjustment quakes.

Tremor Gradually Increasing Again At El Hierro

Harmonic tremor at El Hierro is very gradually increasing, at an almost imperceptible rate, but it is occurring. The tremor from yesterday to today is now about twice as strong as it was, but is still very low, and the eruptive vent is not displaying any surface activity at this time. This could mean that the magma is slowly (and I mean VERY slowly) building up again and is re-pressurizing the vent. At this time however, this is all uncertain, and we will need to wait and see if this is an anomaly, or a pattern.

Tremor readings at El Hierro, showing a very slowly increasing amplitude.

The eruption at El Hierro has been at a very low level the past couple of weeks, but is still apparently ongoing. The eruption is being compared to submarine eruptions in Hawaii such as Loihi, in that underwater flows are continuing slowly, but surely. Degassing is still taking place, although at a very low level compared to a couple of weeks ago. The "Jacuzzi" is spotted intermittently, but remains weak and doesn't stick around for long. It is possible that the activity could resume, or simply diminish.

2.0 Magnitude Quake Strikes Eyjafjallajökull

A Magnitude 2.0 quake struck the Eastern flank of Eyjafjallajökull today, near the same spot of the initial fissure eruption at Fimmvörðuháls. There could be many explanations for this quake, such as structural settling of the post-eruption fissure region, or resumed intrusion of magma into the Eyjafjallajökull-Katla transform region. It is simply too early to tell as this quake pretty much happened within the last hour, so this will be a short post until/if anything further occurs in the region.

There were also two >1.0 mag quakes within the Katla caldera.

Other areas of Iceland experiencing heightened seismicity include the Reykjanes peninsula near the Brennisteinsfjöll volcanic field where more than 27 quakes, two above magnitude 3.5, have struck within the last 24 hours. An area to the East, near Hengill volcano is experiencing continued seismicity due to geothermal exploration and power generation (Iceland is the worlds biggest user of geothermal energy). The quake swarm at Brennisteinsfjöll is strong, and is probably related to magma dike intrusion, however the area has not seen any eruptions since the 14th century, so it is difficult to say what's happening here. Harmonic tremor is being detected at this location, so the quakes are most likely volcanic in nature.

Tremors at Reykjanes peninsula within the last 48 hours.