Friday, April 26, 2013

Puzzling Seismicity at Helka, Iceland

Hekla volcano in Iceland is not known for giving much advance warning, but this time it may be. Scientists in the area have been monitoring the notorious volcano for signs that it may erupt, as it is "overdue" for a show. Hekla is one of Iceland's most active volcanoes, and also one of its most disruptive. Typically this volcano does not give much warning in the way of tremor or earthquakes, indeed the earthquakes seem to precede an eruption only by hours... yet Hekla has been rumbling now for weeks.


Image copyright Icelandic Meteorological Office at http://en.vedur.is

The above photo details tonights seismicity, and while a 1.0 quake in its vicinity may seem benign, this website does not keep a visual record of quakes over 48 hours. As of now there have been dozens along the fissure zone, main volcano, and the NW area seen here in the picture. Volcanoes don't always behave the same way, sometimes their eruption signals can change. Any seismicity and deformation in the Hekla volcanic system can be reason for worry. Previous eruptions came with not a lot of warnings, as is the case with several volcanoes in the region. 

While Eyjafjallajökull created a bit of havoc for the world in 2010, as well as Grimsvötn (Grimsnes), an eruption of Hekla now has the potential to be every bit as bothersome to the Icleandic people. From pyroclastic ash eruptions to fissure fed lava effusion, this volcano is capable of a varying medley of eruptions, and the last time it erupted was in 2000. The volcano has within the last several decades erupted nearly every 10 years, however the volcano has not always done so, so prediction is not possible. 

A list from the Icelandic Meteorological Office at http://en.vedur.is/earthquakes-and-volcanism/articles/nr/1874 details the following Icelandic eruption dates (last two known eruptions in Iceland left in for reference):

2011 Grímsvötn
2010 Eyjafjallajökull
2000 Hekla
1991 Hekla
1981 Hekla
1980 Hekla
1970 Hekla
1947 Hekla
The Smithsonian GVP profile is below:

Volcano types:
    Stratovolcano
    Fissure vents
Summit Elev: 1491 m
Latitude: 63.98°N
Longitude: 19.70°W
One of Iceland's most prominent and active volcanoes, Hekla lies near the southern end of the eastern rift zone. Hekla occupies a rift-transform junction, and has produced basaltic andesites, in contrast to the tholeiitic basalts typical of Icelandic rift zone volcanoes. A 5.5-km-long fissure, Heklugjá, cuts across the 1491-m-high volcano and is often active along its full length during major eruptions. Repeated eruptions along this rift, which is oblique to most rifting structures in the eastern volcanic zone, are responsible for Hekla's elongated ENE-WSW profile. Frequent large silicic explosive eruptions during historical time have deposited tephra throughout Iceland, providing valuable time markers used to date eruptions from other Icelandic volcanoes. Hekla tephras are generally rich in fluorine and are consequently very hazardous to grazing animals. Extensive lava flows from Hekla's historical eruptions, which date back to 1104 AD, cover much of the volcano's flanks.

Tuesday, April 16, 2013

7.8 Mag Quake Strikes South Eastern Iran

A 7.8 magnitude quake struck Iran near the city of Khāsh, near the Iran/Pakistan border, at a depth of approximately 82km. The quake was felt thousands of miles away and could easily be felt in New Dehli, India. The quake occurred about 66 miles East of the Iranian volcano of Taftan, which displays summit fumerolic activity, and has a (questionable) history of modern era eruptions. Another volcano in the (somewhat) near vicinity is Bazman, which also displays fumerolic activity, but like Taftan has no confirmed history of historical eruption.

Large earthquakes this close to large stratovolcanoes can be a concern, as plate slippage may generate magma injections, or destabilize magma chambers with pressure or rock fractures. It is far, far too early to tell whether this might be the case for these volcanoes, but I suspect that activity at them will not change given the history of large quakes in the area, and the fact that the volcanoes (as far as we know) haven't had any confirmed eruptive activity in recent times. But as is the case with volcanoes, you never truly know what they are up to.

Injuries were reported in an area that is home to around 400,000 residents, but the exact numbers have yet to be accurately reported. many buildings were damaged or destroyed in multiple areas.

Iran recently experienced another damaging earthquake at mag 6.2 near one of its nuclear power plants. Official statements from Iran following the quake indicated that the size and location of the quake would not deter the building of new plants, and a joint statement form Iran, and the Russian company that built the plant estimated that the nuclear facility could easily withstand a quake of up to magnitude 8.0. It is unclear if the current quake was near any such facility, but that has not been in any of the reports that I have read so far.

Aftershocks will most likely plague the area for a couple of days, if not for weeks, and more moderate shaking is probable. As Iran does not have a very public interface for volcanic monitoring, any change in activity is likely only to be reported on either social media, or other less-than-reliable channels unless NASA or an equivalent space program directs its satellites to check them out. More than likely, the volcanoes will keep on doing what they've been doing... a whole lot of nothing.


Google Earth/USGS snapshot of quake location and vicinity of 'active' volcanoes. 

Friday, April 12, 2013

Mt. Etna Enters Eruption Phase

While Etna is one of the most active volcanoes on the planet, it typically has short "paroxysms", or short lived explosions with lava effusion. Yesterday it entered into a Strombolian eruption phase which is sustained as of right now. A Strombolian eruption consists of explosive activity with lava fountaining. A Facebook statement from INVOLCAN says "The Director of the Division of INGV-Catania, Domenico Patané, confirmed that "this time is not a paroxysm, it is a real eruption. Already at the beginning of April it had given indications that something was changing and a few days ago we had a very long pre-eruptive activity, 08 April 2013, with explosions of ash that lasted until the evening of April 10, when it changed to the Strombolian explosions started already in the afternoon. During yesterday afternoon activity gradually increased to become almost continuous overnight, with strong explosions and emissions of two small rivers of lava from the edge of the crater, and the area southeast of the "saddle" between the two cones of the Southeast Crater. The last eruptive phase of this type, occurred between May 2008 and July 2009 at the Eastern base of the crater to the Northeast."

The volcano does not typically erupt with this sort of force. Typically it has effusive eruptions and can generate long lava flows, but occasionally it can put on a more dangerous eruption type. The best Enta webcam angle I could find can be found here. The refresh rate is slow, but the shot is very good.

Etna is one of the best monitored volcanoes on the planet, so typically seismologists and volcanologists know what to expect from the volcano, and can warn people not to climb the mountain, or to stay indoors when there is heavy ash emission. Eruptions are typically restricted to summit and flank cones, and there are very rarely any injuries or fatalities.

Wednesday, April 3, 2013

Tjörnes Fracture Zone Has Large Ongoing Quake Swarm [Updated]


The Tjörnes fracture zone in Northern Iceland is showing large amounts of quakes in a swarm that has been ongoing for several days now. Many of the quakes are above 3.0 in magnitude, and are at shallow depth. The area, much like the rest of Iceland, is a spreading/transform fault assembly on the Mid-Atlantic ridge. These quakes could be both tectonic and volcanic in nature, although at the moment no eruptive activity is reported, however it is possible that submarine activity is occurring.


Image from Iceland Meteorological Office

The swarms are occurring near the small island of Grimsney, and the surrounding areas. The largest events, a magnitude 5.3 and 4.7 quake, show up on USGS sensors. Hundreds if not thousands of quakes have occurred within the last few days.

This is a frequent event for this seismic zone. Any eruptive activity, if any, would likely be submarine and not pose a threat to islanders, or the rest of Europe, but Iceland does have a history of creating new land when it wants to as we learned from the 1963-1967 eruption of Surtsey (part of the Vestmannaeyjar volcanic system), which grew a new island out of the ocean during a submarine eruption.

This is unlikely at this point, but if anything further takes place aside from the shaking, it would no doubt be a pretty cool event for volcanologists and those that like to watch the Icelandic volcanoes.


****UPDATE 4/4****

Some reports of volcanic activity are trickling in regarding 'lava on the ocean floor', and heightened emissions. I am trying to pinpoint a reliable source, so far this has only been mentioned on Jon Frimann's Iceland Geology Blog in his comments section. If true this would definitely explain the large amount of concentrated earthquake activity, as this is a rift zone, prone to seafloor spreading events. I am tracking down his sources to see if they pan out, but so far this is word-of-mouth only at this point.

Monday, April 1, 2013

BREAKING: Yellowstone Moved to Highest Alert (Red) After Tremor, Wildlife Fleeing

Just in:

Yellowstone National Park and USGS are sounding the alarm bells, as near constant harmonic tremor has been detected at very shallow depths of less than 1km. Birds, elk, bears, and other wildlife are fleeing into surrounding areas, resulting in scientists at the USGS raising the alert level to RED. "What we are witnessing is unprecedented in recent history in the park" said USGS volcanologist Peter Fitzgerald. "It is really something, really scary. We haven't seen this level of seismic activity in the park since the late 70's, but this is way stronger". Asked if this meant an eruption could be imminent, he stated "At this time, I think it would be a great idea to prepare for the worst.".

Other indicators that an eruption could be underway can be seen on the surface, as near constant emission from Yellowstone's iconic "Old Faithful" geyser stopped the clockwork schedule that has existed for centuries, turning it into more of a 'fountain' than a geyser. Local rangers were baffled as well, when the famed "Prismatic Pools" were devoid of any liquid. "Something big is definitely happening", Sgt. Darryl Langford stated "I am heading home to my wife and kids, they don't pay me enough to be blown up!".

GPS instrumentation detected strong uplift from the West side of the caldera, and water levels have shifted to the East of Yellowstone Lake. Indications are that any explosive/effusive activity will most likely occur at the East rim of the Island Park caldera.

In a brief press statement before rushing off in a hurry, USGS volcanologist Peter Fitzgerald stated "The only safe place in the US right now would be San Diego, CA... as if their perfect weather wasn't enough, it seems by our predictions this will be the only safe city in the US post-eruption. We are estimating over 1.5 million cu km of ashfall debris to be ejected if our models are correct. It was nice knowing all of you".

The last eruption from Yellowstone was thousands of years ago, but scientists have long known this day would happen eventually. Thankfully, I already live in San Diego... but sadly, this means most of my readers are about to be forcefully unsubscribed...



















Oh, who am I kidding? Happy April Fools Day!!