Seismicity Picks Up At El Hierro

El Hierro Island in the Canaires made headlines last year when a submarine eruption occurred less than a mile off the coast of the fishing village of La Restinga, creating an underwater cinder cone, and providing a demonstration of a Serretyan eruption (An eruption consisting on gas filled lava 'balloons' that burst at the ocean surface in a puff of flame, only to sink to the ocean floor and pile up) that thrilled scientists and other volcano enthusiasts. The eruption technically ended some time after the government said it did, but lately seismicity has been picking up and the epicenters of the quakes appear to be getting shallower.

As far as the folks over there at Earthquake-report.com are concerned, they have been on top of things from the get-go with a 'reporter', Joke Volta, on the ground, taking daily pictures and reporting on any earthquakes or changes.

The last few days have seen on average 5-10 smallish quakes, with some larger (mag 4.0 and up) earthquakes. When the seismic swarms resumed, the depths and locations of the quakes were fairly consistent, with most being at the Western tip of the island, 20km below a lighthouse. These quake swarms have now migrated to the center of the island in the area known as El Golfo (the area that resembles a crater, but is actually the result of an avalanche thousands of years ago), and are now occurring at shallower depths (the latest swarm is taking place at a depth of around 12km).

INVOLCAN and PEVOLCA, in conjunction with ER seem to believe this is indeed related to magma dike intrusion at this time, and preparations are underway to possibly raise the alert level of the volcano again from "Green" back to "Yellow", but this is only preparation and precaution, and as of now there is no cause to actually raise the alert level, although I suspect if the quake swarms continue for a lot longer, we will probably see the alert level raised, and maybe even another eruption from the island.

Deformation on the island lately has been stable, although since the end of the last eruption, the island has been uplifted some 10cm! This clearly indicates magma rising in the chamber. Some subsidence has occurred, but for the most part the island right now is stable. Time will tell what the results will be.

*****UPDATE 8/17/2012*****

Earthquake-report.com is reporting over 58 quakes have occurred in the last day in the El Golfo region of El Hierro.

Large And Shallow Earthquake Swarm Near Aniakchak Volcano

Aniakchak volcano in Alaska is one of the largest, and most active volcanoes in the Aleutian arc. The volcano contains a 10km wide caldera, with multiple cinder cones occupying the ~3400 year old caldera floor. The last eruption of Aniakchak occurred in 1931, which marked the only known historical eruption of the volcano.

A large earthquake swarm struck approximately 25 miles NE of Aniakchak on August 3-5, centered between Aniakchak volcano and the lesser-known Yantari volcano (which apparently had a very Mt. St. Helens like eruption in pre-history). The largest quake was a 4.7 magnitude quake at a depth of around half a kilometer (which is very shallow). Many other shallow quakes, some with similar magnitudes have occurred (see the below image) since.

Google Earth plugin with USGS real-time overlay enabled showing the location of the quake swarm

The depths of most quakes in the area are usually some hundreds of KM deep, as this is a subduction zone where one plate slides underneath the other. Occasionally this process generates a magma vein, that results in dike intrusions and the birth of most of the world's stratovolcanoes.

This quake swarm is curious due to its location and the very shallow depths. New volcanoes have been born in Alaska in the past, sometimes with disastrous results such as the eruption of Novarupta, the largest eruption of a US volcano in recorded history. While it is likely that this is a magma dike intrustion into the crust, it is impossible to say what might occur if the swarm does not return, or no new magma is injected into the crust. Most dike intrusions do not result in an immediate eruption, and some times they never do.

In any case, I will be keeping a close eye on this, and possibly email AVO about the swarm and see if they were aware of it (which I am sure they were) and whether they might be able to shed some light on it for our readers. Stay tuned!

*****UPDATE 8/9/2012*****

Another single quake at a depth of 5km measuring 2.5 occurred today in the area. This is the first aftershock/tremor in a few days. I have contacted AVO requesting information on the current swarm, and hopefully will hear back from them soon!

*****UPDATE 8/10/2012*****

AVO responded to my email with the following response:

"They're regional tectonic earthquakes. We have no indication that these earthquakes have anything to do with volcanism.This series of earthquakes, at this time, is not alarming to us."

So it appears that there may be several faults criss-crossing the Aleutians that occasionally have these shallow types of quakes occur, even very near active volcanoes.

Swarm Of Quakes Rattle Los Angeles, CA

A series of moderately sized earthquakes and associated aftershocks hit the Los Angeles (Yorba Linda) area in California today and yesterday, with two quakes registering 4.4 and 4.5 on the Richter scale being the largest tremors. Residents as far south as San Diego County reported feeling the quake, and near the epicenter it was reported to feel quite strong. The quake depths were from 10km-8km for the largest tremors. Many shallower aftershocks, most at or around M2.2 (but some at 2.9) have occurred, and are still occurring as of now.

Los Angeles is no stranger to earthquakes, and as such, has building codes that normally prevent any damage. In California, most buildings must be built to be able to withstand up to a magnitude 8.0 quake as a building standard.

Interestingly enough, the quakes did not occur on the famed San Andreas fault line that extends from Baja California, Mexico, to central California in the US. These quakes occurred some 35 miles SW of the nearest point to the fault at Cajon Junction. These quakes occurred on a smaller fault that runs under Yorba Linda. This fault line is quite small compared to its larger, more violent neighbor, the San Andreas, running only tens of miles in a NW/SE direction. (Given that this is a volcano blog, I should note that these quakes are in NO WAY related to any type of volcanism).

It is likely that more smaller aftershocks will follow for a few days in the area as the fault settles down. It is possible that these quakes may destabilize other faults in the area, however at this time this is only a 'maybe', as scientists still struggle to really figure out how parallel faults affect one another. Earthquake dynamics are highly complex with many factors that go into causing them, and even more factors in the aftermath to consider. 

New Concerns About Campi Flegrei in Italy

There are less than 20 so-called "supervolcanoes" on Earth, and of those some are well known, and some are not. From Yellowstone to Taupo, Toba to Uturuncu, and more, we know that these volcanoes erupt with extreme volatility, yet very rarely... with the exception of some. The most recent magmatic eruptions from any known supervolcanic caldera has occurred in the Aira caldera in Japan, where the resurgent Sakura-Jima stratovolcano has been erupting in the center of the caldera for many decades. The most recent actual supervolcanic eruption (VEI 8) occurred over 75,000 years ago at Lake Toba volcano in Indonesia, which, according to widespread genetic analysis, may have reduced the modern human population to under 5,000 individuals worldwide (although the maximum population at that period has never actually been quantified).

Indeed, supervolcanoes are a terrifying thought, however these events are so rare, and nearly unpredictable (according to current science) that one should not even sweat one drop worrying that this may occur...

But this is not the case in Italy, as the Campi Flegrei volcano is again in the media spotlight (as occasionally Yellowstone or Uturuncu is when news outlets want some ratings).

As I have reported previously on this blog, Campi Flegrei is the site of a study that seeks to better  understand the dynamics and goings-on in the magma chamber beneath Pozzouli, Italy. The area boasts a population of over 3 million people, and any eruption from the restive caldera would be of grave concern to the government, and to the population. As recently as 2010, industrial drilling has taken place at the volcano, however once scientists proposed a drilling operation that would reach the magma chamber, unfounded concerns by non-experts forced the operation to be on hold until recently.

Now, a team of geologists will drill some 3.5+ km into the magma chamber in an effort to monitor and detail the dynamics of one of the world's most active super volcanoes. The last eruption from the Campi Flegrei field produced the Monte Nuovo cinder cone in 1538, which was documented thoroughly by local witnesses of the time. Earlier volcanism produced several solfatara fields, and modern-day activity has consisted mostly of fumerolic/phreatic activity, and gradual uplift of the caldera area, which in the 1980's prompted evacuations of some areas due to the rate at which the land was rising.

Current uplift has left some modern and ancient nautical ports/docks inaccessible due to he gradual and constant uplift of the land. In one port, the land has risen so much that the cement boat launch platform that used to serve the area pre-1970 is now so elevated that you might consider using it as a diving platform rather than a place to launch your boat.

Campi Flegrei is monitored by the Vesuvius volcano observatory in Italy (Vesuvius, another powerful and notorious volcano is located a mere 15km East of the Campi Flegrei Caldera), and lately, no warnings have been issued in regards to seismic swarms, magma intrusion, or increased fumerolic or solfataric activity in recent memory.

There is not enough data that currently exists at this time to say what the next phase for this sleeping giant would be, but most sources that know what they're talking about would tell you this: A super volcanic eruption is a rare event, which requires rare circumstances. The conditions at Campi Flegrei, and every other super volcano in the world suggest that while we are now aware of the existence of such volcanoes, we should sleep well at night knowing that none of them are currently capable of producing the conditions for such a natural disaster. Not even Yellowstone.

Fish Kill Reported at Krísuvík Volcano in Iceland

Krísuvík Volcano in Iceland has not erupted for centuries, however the area and its lakes remain rife with fumerolic and hot spring activity. Recently it was reported by Icelandic media and volcano-blogger Jón Frímann that Kleifarvatn lake, a part of the Krísuvík volcanic system, that divers and visitors have been noticing lots of dead fish in the lake. While it is unclear whether or not the fish population in the lake has indeed been hit by unusual activity, fish kills in volcanic lakes are typically a good indicator of volcanic activity.

There are many deadly volcanic lakes in the world, the most notable and famous of which was Lake Nyos in Cameroon which, after a small landslide, caused the liquid CO2 at the bottom of the lake to stir, and escape to the water's surface, eventually escaping the boundaries of the large maar-lake, and inundating lower elevations with deadly amounts of CO2 that killed thousands in a matter of hours.

Kleifarvatn lake lies in parallel with the crater rows of Krísuvík's volcanic system which consists of fissure vents, cinder cone rows, and flood basalts, which last erupted sometime in the late 14th century. The lake itself lies on a low point of the spreading rift, and thus is a great lake to capture gases under water pressure, much like lake Nyos. It could simply be that recent seismicity in the area has stirred up the gases, which mix with the water level the fish typically are at, thus suffocating the fish with volcanic gases and killing them.

It is a trend to watch however. There have not been any studies yet done by local scientists, so right now we don't really know if there have been other changes in the lake such as increased Ph levels, temperatures, or other increases in gas from source vents under the lake.

Fish kill is always a sign to look for if there is anything ominous going on at any volcano. Several episodes of fish kill have occurred near my hometown of San Diego at the Salton Sea, which was related to release of volcanic gases in one instance, but another instance was caused by farm water runoff into the lake that ended up making it one of the most polluted lakes on the planet (a disgusting distinction for an area of the world that is so beautiful). Few people in San Diego or California actually realize that the Salton Sea (who's volcanic counterpart is known as the Salton Buttes) is really a volcano, with fairly recent geological history.

As with the Salton Sea, Krísuvík volcano is also near an actively producing geothermal field. Geothermal drilling can and does cause seismicity which can disturb lake sediments and result in the loss of marine life due to particulates like sediment, and volcanic/organic gases like methane and CO2.

Right now it's all speculation until I can see a study done by scientists that show chemical levels and demonstrate a clear increase in activity. As with much of Iceland, most of the volcanoes there are constantly steaming or releasing some kind of gas, so this may not be unusual for this particular volcano. The lake is lines with steam and hydrothermal vents, hot springs, mud pools, and all sorts of avenues for gases to be released, so it wouldn't surprise me in the least to learn that this has been going on in this lake for a very long time.

In any case, I'll follow up with this volcanic lake if anything new should develop. Stay tuned!