Thursday, July 26, 2012

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!

Wednesday, July 25, 2012

Famed Mount Tongariro in New Zealand Shows Spike In Seismicity

The volcano made famous in New Zealand (for something other than erupting) by the movie franchise "The Lord of the Rings", as a stand in for "Mount Doom" is showing signs of increased seimicity and gas levels. The Smithsonian GVP's report today had this to say about Tongariro:

"TONGARIRO North Island (New Zealand) 39.13°S, 175.642°E; summit elev. 1978 m

A sequence of small volcanic earthquakes beneath Tongariro was detected by a few of the seismometers in the permanent network. Earthquakes with magnitudes less than 2.5 were clustered between Emerald Crater (E of the summit) and the Te Mari craters (2 km E east of Ketetahi hot springs on the N flank) at 2-7 km depth. The sequence started on 13 July, soon declined, and then again increased during 18-20 July. The Alert Level was raised to 1 (on a scale of 0-5) and the Aviation Colour Code was raised to Yellow (on a four-color scale) on 20 July.In response to the increased seismicity, GeoNet installed four portable seismographs and conducted gas and spring sampling. During 21-22 July seismicity declined; one event was detected on 23 July.

Provisional analysis of the gas samples collected during 21-22 July indicated a marked increase in the volcanic gas component of the typical mix of volcanic and hydrothermal gases. Residents reported a gas odor.Geologic Summary.

Tongariro is a large andesitic volcanic massif, located immediately NE of Ruapehu volcano, that is composed of more than a dozen composite cones constructed over a period of 275,000 years. Vents along a NE-trending zone extending from Saddle Cone (below Ruapehu volcano) to Te Mari crater (including vents at the present-day location of Ngauruhoe) were active during a several hundred year long period around 10,000 years ago, producing the largest known eruptions at the Tongariro complex during the Holocene. The youngest cone of the complex, Ngauruhoe, has grown to become the highest peak of the massif since its birth about 2500 years ago. The symmetrical, steep-sided Ngauruhoe, along with its neighbor Ruapehu to the south, have been New Zealand's most active volcanoes during historical time."

Tongariro's last known eruptive period was from 1974-1977 according to the Smithsonian GVP. The eruptions have been mostly pyroclastic in nature, with a history of phreatic eruptions and cone building events. The volcano has remained relatively quiet since 1977, and contains a crater lake at the NE summit, as well as a few smaller ones called 'The Emerald Lakes'. Plenty of fumerolic activity occurs near the lakes, which were apparently a nice place until recently to take a dip.

An eruption at Tongariro today has the potential to disrupt air travel for New Zealand and Australia, and older lava flows (not historical) cover farmlands to the NE of the summit. 

Tuesday, July 24, 2012

Possible Resumption of Eruptive Activity at Nabro volcano, Eritrea


Nabro volcano, who's last eruption was the first ever recorded in historical time, is possibly showing signs of activity again. A blurb on Earthquake-report.com shows a picture which may or may not be a volcanic plume over Nabro (there are no other clouds in the area from what the picture shows), but from the picture it is hard to tell if the plume is from Nabro or neighboring (to the SW) volcano Mallahle, which has not had any historical eruptions (last known eruption was probably holocene but like many volcanoes in this violent region of the world, studying them is a tough prospect), so it is more likely that Nabro is showing some degassing rather than Mallahle.


                             

The image could also just be high elevation clouds, which do occur frequently at mountain peaks during periods of lower barometric pressure and higher relative humidity at that elevation. It is impossible to say at this time whether or not this is actually an eruption plume, or just clouds. Satellites did not detect any CO2, so my guess is that this is just water vapor, but I will keep my eye on Nabro as its last eruption was spectacular, producing an over 14km lava flow and producing large clouds of ash that impacted Ethiopia and Eritrea heavily.

Reports from this region are rare, as both nations are not safe to travel to given the political and military situations over there. Any reports about this volcano will likely come from satellite observations, and nothing more as the region is not equipped with great communications, nor do they have any well funded volcano monitoring programs.




Monday, July 23, 2012

Small Earthquake Swarm at Krafla Volcano, Iceland

Iceland

A series of small quakes has occurred at Krafla volcano in Northern Iceland. A series of about 10-12 small quakes, the strongest being near mag 1.5, occurred swiftly with maybe one or two very small aftershocks in the area. Krafla volcano last erupted in 1984 in a series of fissure fed events, and multiple inflation and deflation events. It is one of Iceland's most active volcanoes alongside Grimsvötn (or Grimsnes), Hekla, and Katla.

The depths of these events are unknown according to my computer analysis, but I suspect these quakes may have occurred due to geothermal prospects int he area, however this could also be related to a very minor dike intrusion under the volcano, as the locations of these quakes seem to suggest activity in the center of the topographically indistinct caldera region.

The Smithsonian GVP characterizes Krafla:

"The Krafla central volcano, located NE of Myvatn lake, is a topographically indistinct 10-km-wide caldera that is cut by a N-S-trending fissure system. Eruption of a rhyolitic welded tuff about 100,000 years ago was associated with formation of the caldera. Krafla has been the source of many rifting and eruptive events during the Holocene, including two in historical time, during 1724-29 and 1975-84. The prominent Hverfjall and Ludent tuff rings east of Myvatn were erupted along the 100-km-long fissure system, which extends as far as the north coast of Iceland. Iceland's renowned Myvatn lake formed during the eruption of the older Laxarhraun lava flow from the Ketildyngja shield volcano of the Fremrinamur volcanic system about 3800 years before present (BP); its present shape is constrained by the roughly 2000 years BP younger Laxarhraun lava flow from the Krafla volcanic system. The abundant pseudocraters that form a prominent part of the Myvatn landscape were created when the younger Laxarhraun lava flow entered the lake."

Krafla is highly active, geothermally speaking. It boasts many fumeroles, mud pots, and fissure systems. The last eruption began in 1974, and ended in 1984, a 10-year cycle that produced massive amounts of magma. Eruptions from Krafla today would likely not produce massive amounts of ash, rather it would most likely be a repeat of the previous eruption with fissure fed lava flows, and flood basalts that would no doubt produce a large amount of CO2/SO2 emissions, but otherwise be largely undamaging to populations near and around the world. One casualty, if the volcano should erupt, would most likely be the loss of geothermal prospecting in the area, which could also be the main cause of the recent quakes.

Personally, I would not be very worried about an eruption from Krafla, but I would be very excited to see it happen. These fissure eruptions do not occur worldwide very often, with the exception of Kilauea in Hawaii, and some volcanoes in the Great African Rift Valley, so an eruption like that would produce some very spectacular pictures and video indeed!

Iceland is always a fascinating place to keep an eye on. Even when volcanoes are not erupting, there are always plenty of volcanic-related things to see such as the famed Blue Lagoon, and the newly opened Thrihnukagigur volcano tour, where you are actually lowered into an extinct (or dormant) volcano's magma chamber! Not to mention the famed Hekla volcano, of which many people in the Viking era considered to be the 'official' entrance to Hell. ironically, the famed Viti craters of Krafla and Mývatn literally mean, "Hell", and Icelanders for many centuries believed that volcanoes were the physical entrance to such a place.

This most recent event is most likely a random anomaly, and probably not significant, however Iceland is a fascinating and random place as far as volcanoes are considered. Eyjafjallajökull erupted with little more than a month's notice after several centuries of inactivity, and other frequent offenders have laid dormant for decades. It is truly a landscape of unparalleled beauty and danger, and one of the few spots on the planet where you can be an eyewitness to how the earth builds land!

Sunday, July 1, 2012

Nabro Volcano, Eritrea, Has Seismicity In The Region

Nabro volcano, which had until recently been dormant (or considered by some to be extinct), erupted last year on July 12th, 2011, with a rather large ash cloud followed by a massive lava flow that covered several square kilometers. This eruption was preceded by a 5.1 magnitude earthquake. While reports out of the area are scant, the volcano was widely considered to have ended its latest period of activity many months ago, however there have been no real follow up reports detailing the eruption from start to finish, at least to international media online.

Earthquake-report.com is reporting renewed seismicity in the area as of today, with a 4.8 magnitude tremblor taking place SE of the crater/caldera area. This is not an insignificant quake for a volcano, however this could be purely tectonic, given that there have been no follow up quakes, harmonic tremor, or other signs that this might be volcanic at this time. This could also be yet another sign of the volcano awakening again, which could cause some problems for neighboring countries.

The volcano is situated in Eritrea, but borders Ethiopia, and Djibouti is the nearest science station that can record seismic signals from the war torn region. Most expeditions to the area are difficult and hamper direct scientific observation. It is likely that even if an eruption were to occur in the area, we would, like last time, hear about it from Ethiopia, or NASA.

At this time is is far too early to speculate on whether this is a volcanic or tectonic event, but if anything new occurs, I will post an update.

Strong Quake Swarm SSW of Cerro Prieto, Mexico

A minor swarm of earthquakes hit several miles SSW of Cerro Prieto in Mexico, near the US border (and my hometown of San Diego County). The largest quake was measured at 4.7 by USGS, however there were two subsequent tremblors of 4.6, and 4.1, as well as many magnitude 3 and under. This occurred along the same fault line that eventually transforms into the San Andreas fault, and begins between mainland Mexico, and Baja California, Mexico.

No damage has been reported so far.

The epicenters of the quakes are several miles south of the epicenter of the last large quake in the region, (a 7.4 magnitude quake in 2010 that was dubbed "The Easter Quake). I was present very near the epicenter and experienced this firsthand. The current quake swarm is likely a result of this quake, as the region has experienced many minor to somewhat large tremors since the Easter Quake. This is most likely due to crustal adjustments, and settling, and not a precursor toward volcanic eruption. However just NW of the epicenter lies a more than 10,000 year old small volcano cone name Cerro Prieto. Just NNW of that cone, lies the Salton Sea, another volcanic center which has also experienced Holocene eruptions, and is, as well as Cerro Prieto, an actively producing geothermal field.

The GVP describes local Cucapas Indian legends of a monster rising from the earth and emitting "Fire tongues", which has been interpreted to mean a description of the growing volcano in its infancy. While neither Cerro Prieto nor the Salton Sea has seen any volcanic activity during recent historical times, it is an area that will likely have an eruption in the earth's future. Current displays of volcanic activity can be found at the Salton Sea by way of fumeroles, and mud volcanoes, as well as the geothermal power plants in the area. In the Cerro Prieto region, geothermal plants dot the area, and during some quakes, it has been reported that spouts of sulfuric smelling water, red in color, emanate from the landscape like geysers, however only briefly.

During the 7.4 magnitude quake, the area was lightly reported to have had increased surface activity from geothermal forces.

The activity in the area is caused by light crustal spreading, and impaction northward. As the plate grind North, they also spread slightly at the Pacific/North American Plate boundary, near San Diego, CA, pulling Baja California away from mainland Mexico, yet upwards toward the mainland USA.

The current quakes are not volcanic in nature, however the area will someday experience eruptive activity. In the near future however, this is not likely to happen.