Category Archives: Geothermal

Today in Geological History; June 10th – Tarawera

Standard

Today marks the 130th anniversary of Tarawera bursting back to life after 500 years of sleep. It was one of New Zealand’s largest eruptions in recent history and killed up to 150 people making it the countries most deadly since the arrival of the Europeans.

Members of Te Arawa hapu Tuhourangi and Ngati Rangitihi will, weather permitting, make their annual pilgramage to the top of Mt Tarawera today for the 130th anniversary of the eruption.  Photo/File

Tarawara was last active in 1315 and is believed to have had a great hand in the Great Famine of 1315-137 throughout Europe. In 1886 the mountain gave little warning of up coming events. On June 1st a series of waves were recorded on the surface of Lake Tarawera suggesting seismicity in the area although no one reported feeling quakes and there where no seismometers at this time. Tourists claimed they saw a phantom canoe floating across the waters with Maori warriors on board. Although there were multiple accounts on the sighting many believed it was simply a rogue wave caused by increased seismicity, tribal elders at Te Wairoa however claimed that it was a waka wairua (spirit canoe) and was a portent of doom.

Charles-Blomfield-Mount-Tarawera-in-eruption-June-10-1886.jpgAll was quiet again in the following days and people though little of the complex. Many geologists at the time didn’t even consider the edifice to be active due to the lack of solfataric or fumarolic activity in comparison to New Zealand’s other volcanoes.

At 2am local time on June 10th this all changed. Locals where awoken by large tremors shortly followed by explosions heard as far away as Blenheim over 500 km to the south. by 2.30 all three peaks of Tarawera were eruption with fire fountains lighting up the pitch black, ash filled skies. The eruption began to the northeast side and spread rapidly along a fissure from Tarawera to Lake Rotomahana into the Waimangu Valley. The eruption was believed to be caused by a series of basaltic dikes which rose from depth and intersected the very active hydrothermal system under Tarawera and Lake Rotomahana, causing rapid steam/magma explosions, driving the plume that was observed and creating, by some accounts, fire fountains as tall as 2 km which explains the high explosively of a basaltic eruption.

The darkened skys were seen as far as Christchurch and was catapulted in the stratosphere where it lingered effecting climate for at least a year. The ash fall from the eruption – called locally the “Rotomahana Mud” – can be found into the Bay of Plenty almost 40 km away. This tephra covered 15,000 km2 over the North Island and over 4,500 km2 of the area with at least 5 cm of tephra.

The eruption itself produced at least 1.3 km3 of tephra (~0.7 km3 of dense rock equivalent), likely at a rate of higher than 6 x 104 m3/s. It also produced a base surge that travelled over 6 km from the craters moving 40 m/s and were large enough to top hills that were 360 meters tall which buried several Maori villages.

The Buried Village Rotorua

The Buried Village Rotorua is now a popular tourist destination often branded New Zealand’s answer to Pompeii. As well as the human impacts it also buried the Pink and White Terraces.

 

 

Figure 1; http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11653679

Figure 2;  https://en.wikipedia.org/wiki/1886_eruption_of_Mount_Tarawera#/media/File:Charles-Blomfield-Mount-Tarawera-in-eruption-June-10-1886.jpg

Figure 3; http://www.visualitineraries.com/VisitPoint.asp?location=419&title=Rotorua+Museum+of+Art+%26+History

Figure 4; http://www.nzonline.org.nz/nzo/business/the-buried-village-of-te-wairoa-rotorua

 

 

Advertisements

Kyushu Earthquake, Mt Aso and the Relationship between Volcanoes and Earthquakes.

Standard

In the past week the Japanese Island of Kysushu has be ravaged by earthquakes.

2016-04-16Japan is a highly seismic area with noticeable quakes in some areas occurring nearly daily.  But things began to escalate for the Kyushu region on Thursday night when a magnitude 6.5 quake brought several buildings down. As rescue efforts began the region had two more huge after shocks during the night, one over Mg 6 and the other > Mg 5. By midday Friday the death toll stood at 9 with over 800 injured and although the aftershocks kept coming many >Mg 4 people were still being pulled from the rubble. Sadly these events were quite possibly a precursor to something larger.

At 01.25 local time (15.25 GMT) a Mg 7.3 struck just north of Kumamoto just kilometers from the large earthquakes which had already occurred. Much of the seismicity in the Kyushu region is related to the subduction of the Philippine Sea plate at great depth. However this series of earthquakes have occurred at very shallow depths several hundred kilometers northwest of the Ryukyu Trench. They have been cause by strike-slip faulting within the Eurasian plate.

Quake damaged houses in Kumamoto, Japan (16 April 2016)So far 22 more people have been reported dead but this is expected to rise in the coming days with at least 80 people known to betrapped in rubble. 11 of which are trapped in a Tokai university apartment in the town of Minami Aso.

 

The shallowness of the earthquakes means damage to the surface is high and it is not just collapsing building which are a hazard. People have fled the area down stream of a dam which collapsed soon after the earthquake. Landslides in the area have taken out roads and power lines and with heavy rain anticipated over the coming days JMA have advised mudslides will be a huge problem for rescuers.

 

 

 

 

 

 

The seismic problems of Kyushu may have also set in motion another geohazard in the form of Mt Aso. Yesterday one of my favorite volcanology bloggers Eric Klemetti tweeted “Quite a few volcanoes on Kyushu and these earthquakes have been centered near Unzen, Aso, Kirishima. This is NOT to say these earthquakes will trigger any eruptions, but could be worth watching over the next year.” Several hours late JMA reported a small scale eruption at Aso. Smoke plumes have migrated 100 meters above the summit and it is not yet clear if the activity is magmatic (caused by movement of magma towards the surface) or phreatic (steam explosion caused by heating of groundwater).

Eruptions and earthquakes do not always come hand in hand but each one can contribute to the other or not at all depending on the circumstances. One indication a volcano is about to erupt is volcanic tremors; these low frequency earthquakes are usually caused by the migration of magma or changes to magma chamber. Although they are rarely higher than a magnitude 4. On the other side large earth quakes can cause faulting in bed rock which allows magma to exploit a new weakness and find a path to the surface it previously could not intrude on. The same can happen for ground water with faulting caused by a quake allowing it to seep in to geothermal areas it previously did not have access to due to the impermeability of the rock. When earthquakes hit volcanic regions volcano observatories always keep a closer eye on vulnerable or highly active volcanoes as a precaution but it is not always needed.

12965168_193557341031357_783094435_n

The Aso Caldera complex has one of the world’s largest calderas. It is comprised of a 25 km north-south by 18 km east-west Caldera and a central cone group comprised of Mt. Neko, Mt. Taka, Mt. Naka, Mt. Eboshi, and Mt. Kishima. Mt Naka where the eruption has just taken place is the most active with its most recent eruption taking place last October. Although much of Aso’s activity in the past century has been relatively small it has had a violent history with at least 4 VEI 7 events in the past 300,000 years.

It’s is not clear whether the earthquakes in the past few days did trigger the current current eruption but JMA are keeping a close eye on the situation and I will update this page as I know more.

 

 

Figure 1. http://earthquake.usgs.gov/earthquakes/map/

Figure 2; http://www.bbc.co.uk/news/world-asia-36061657

Figure 3; http://www.independent.co.uk/news/world/asia/japan-earthquakes-dozens-reported-dead-injured-second-quake-two-days-a6986931.html

Figure 4; http://mashable.com/2016/04/15/japan-earthquake-landslide-photos/

Lake Taupo

Standard

For years a major thing on my bucket list was to swim in a crater lake, which as the name suggests is a body of water formed in a volcanic crater or caldera. Luckily I got to tick this one of when I visited Nicaragua last year and swam in the blissfully warm Apoyo Lagoon, but of course this only appealed to my addictive nature and made me dream about going one better…how about a crater lake formed by a super eruption. When my friend told me she was off travelling for a few months and her first port of call would be New Zealand, I decided she could live my dream for me on this one and I straight away advised her to head to Lake Taupo. Of course to any one without local knowledge or a familiarity with historic eruptions, this would not be of any significance. To be honest neither would me telling them I want to go swim in a random lake in New Zealand. So I decide to write a peace on one of the largest eruptions in the past 70,000 years to explain just why it is so important.

With a surface area of 616 square kilometres (238 sq mi), it is the largest lake by surface area in New Zealand and the second largest freshwater lake in Oceania. Now it’s a popular tourist destination, an area of true natural beauty, but this tranquil lake was born from a violent even which occurred roughly 26,000 years ago.

Volcanoes graphicThe Taupo volcanic zones spans a hug area in North Island 350 kilometres (217 mi) long by 50 kilometres (31 mi) wide. Mount Ruapehu stands 2797 high and marks its southern limits, while a submarine volcano, Whakatane volcano, 85 kilometres (53 mi) beyond White Island is considered it’s north-eastern.  Several volcanoes in the zone are still very active with Ruapehu and Tarawera causing New Zealand’s most deadly eruptions in the past few centuries (both events killing around 150 people each). None of these small events come close to the Taupo volcano itself after which the zone is named. The zone is caused by east-west rifting within plate the at a rate of 8mm per year, slowly pulling the Northern Island apart.

 

Taupo’s last eruption is referred to as the Hatepe eruption and has be dated at roughly 180 AD was a VEI 7 making it one of the largest in the past 5,000 years. It coincided with reports as far away as Rome and Northern China of brilliant red skyies and disruption to climate for several years. Haptepe spewed more material in to atmosphere than several of the largest eruptions of this century combined, but still it was nothing compared to the event which form the Taupo caldera and in turn Lake Taupo; the Oruanui eruption.

The Unit as the level of the volcanologists feet is an exposure of an unwelded pyroclastic flow deposit from the Oruanui eruption. The light- coloured air fall pumice are from varying eruptions between Oruanui and the uppermost layer of deposits which were laid by the Hatepe eruption.

Its hard to imagine what the Northen Island looked like before the Oruanui eruption 26,500 years ago with out the gapping hole that is Lake Taupo at its heart. The eruption released an estimated total of 1,170 km3 (280 cu mi) of material, a VEI 8 eruption making it the largest eruption of the past 70,000 years. It effected climate world wide for decades, many people saying it had a helping hand in the last glacial maximum. The effects are hard to comprehend when the largest volcanic eruption in human times was only a fraction of the size.

The eruption caused the Taupo magma chamber to collapse on its self creating the vast caldera which today Lake Taupo occupies just over two thirds of. Ash fall deposits from the eruption have been documented over 1000 km on Chatham Island showing the intensity of the blast. An event like this would decimate modern day New Zealand quiet possibly leaving no survivors on the Northern Island if not enough warning was given. Luckily though all is peaceful and scerene on the shores of the Great Lake and no threat appears to be imminent. That said Taupo still shows us gentle signs of the power beneath with its Craters of the Moon tourist attraction filled with steam vents and mud pools as well as numerous hot springs.

When people ask me why I study volcanology when the risk is “minimal” to human life in comparison to say earthquakes or flooding, this is a prime example which shows how little people know about what our planet is capable of. So Ginge, I hope you enjoy your trip and now understand a little more why Taupo is one part of your adventure I sincerely wish I was there!

 

Figure 1; http://www.waikatoregion.govt.nz/Services/Regional-services/Regional-hazards-and-emergency-management/Lake-Taupo-Erosion-and-Flood-Strategy/

Figure 2; http://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/New-Zealand-Volcanoes

Figure 3; http://volcano.si.edu/volcano.cfm?vn=241070

 

Today in Geological History; 17th January – Northridge and Nyiragongo

Standard

The Northridge Earthquake 1994

At 4.30 am local time, the residents of the San Fernando Valley region of L.A were awoken by a shallow magnitude 6.7 earthquake. It is estimated to be one of the most costly natural disasters the state has faced causing up to 40 billon US dollars and killed over 60 people.

The earthquake struck along a fault line which was previously unknown off, the Northridge blind thrust fault. It produced the highest ever recorded ground motions at the time and literally threw many buildings off their foundations. It sparked greater mapping of the L.A fault systems so places could be better prepared for further destructive quakes in the future.

Some of the most dramatic pictures of the destruction came from the many freeways and interstates which suffered structural failure and/or collapse.

One of the most unusual outcomes of this earthquake was the outbreak of coccidioimycosis, or more commonly known as Valley fever. There were over 200 cases reported in the weeks after the quake and 3 fatalitites. Valley fever is a respiratory disease brought on by airborne spores of fungus. It is thought that landslides caused by the earthquake sent a cloud of the spores in the the air which the wind carried to surrounding areas.

 

Nyiragongo 2002

After months of increased activity at the stratovolcano in the DRC, a 13 km fissure opened along the southern flank of Nyiragongo in a matter of hours. The fissure reached all the way down to the town of Goma and Lake Kivu.

Over 400,000 people were evacuated from Goma and the surrounding area, many across the border to Rwanda. Despite these efforts 147 were killed, mainly from asphyxiation and some from collapsing buildings from volcanic tremors. About 4,500 buildings were destroyed in Goma and two-thirds of its airport left unusable as lava devoured the run ways.

When the flows reached Lake Kivu, due to the high gas emissions, a new fear was put in place. Similar to events at Lake Nyos 1986, there was a chance that the high emissions of carbon dioxide and methane could be stored in the lake waters and released lethal limnic eruption. Although this was not the case there have been numerous cases in the area around Nyrigongo of particularly children dying from asphyxiation due to random degassing of the volcano. An experimental syphon was put in place in 2001 to try to limit the amount of gas in the bottom waters, but it was not untill 2004 when an energy company wanted to harness the gas as a resource, did any really system come in to place to limit the risk of limnic eruption.

Nyrigongo is one of the 17 decade volcanoes, ones believed to pose greatest risk to human life. Caused by a mixture of rifting and hot spot activity, unlike many volcanoes of its kind, its lavas have an extreamly low silica content. Predominately melilite nephelinite, instead if more common more common basalts, it is extreamly fluid and can reach speed on average of 100 km/ph. It has also had a near constantlty active lava lake giving us the gentle reminder that it can fatally burst to life at any time.

 

1. Http://dart2.arc.nasa.gov

2. http://m.utsandiego.com/news/2014/jan/15/northridge-earthquake-anniversary-20/

3. http://www.unisdr.org/2006/ppew/info-resources/ewc2/UK/galerie/pg000057.htm

4. http://www.geo.arizona.edu/geo5xx/geos577/projects/kayzar/html/nyiragongo_volcano.html

Finally back, and the Earth has not been as quiet as this blog!

Standard

Work, uni, a 7 year old, Christmas and life in general has made posting near in possible the past month or so. The volcanoes around the world have been just as busy as I, so here’s a quick summery;

Barðarbunga

Yes this blogs most talked about lava field is still growing. A press release from the Icelandic MetOffice states the lava flow now covers in excess of 80 cubic kilometres.

image

Seismicity continues throughout the length of the dyke and within the Bardarbunga caldera albeit at a reduced rate then earlier in the eruption. Subsidence in the caldera has reached 56 meters in depth, and roughly 1.7 cubic kilometre. Gas emissions continue with elevated pollution warnings still in place through much of Iceland.

On the 29th December the fissure eruption will have been consistent for 4 months, although activity is not as great as in the earlier stages, the eruption shows no indication that the end is in sight.

Kilauea

The June 27th lava flow is still on the move at roughly 300 yards a day. The flow front currently sits less than half a mile away from Pahoa Marketplace where many of the businesses have had to close due to the on coming threat.

image

Sections of the flow have been made available, first for students and journalists, and now public to see the lava up close. Eruptions also continue at Kilauea’s summit and East Rift Zone.

Pico Do Fogo

Follow recent events on the Cape Verde island of Fogo has really triggered an anger inside of me in recent weeks and this eruption will have its own post soon after this one is published. However for a brief over view, Pico do Fogo begain eruption back on November 23rd. Since lava flows have devoured local villages forcing over 1500 to flee their homes. Gas and ash emissions have nearly ceased and lava output is now low, although remaining buildings in the village of Bangaeira are still being engulfed by the flow.

Nevado del Ruiz

This Colombian volcano caused one of the greatest natural disasters of the 1980’s. Seismicity has picked up since December 3rd inducing an increased aviation code to yellow. Ash emissions have been sporadic, with a white plume drifting almost 20 km south on December 15th.

Mayon

During 9-16 December white plumes were occasionally observed rising from Mayon’s crater and drifted WNW and WSW, sometimes downslope. Three volcanic earthquakes were recorded on 9 December and one was recorded on 11 December. Alert Level remained at 3 causing PHIVOLCS to remind residents of the 6-km-radius Permanent Danger Zone (PDZ) around the volcano and the 7-km Extended Danger Zone (EDZ) on the SE flank due to recent rockfalls and threat of eruption.

Suwanosejima 

The Tokyo VAAC reported that on 14 December an explosion at Suwanosejima produced a plume that rose to an altitude of 1.8 km (6,000 ft) and drifted SE.

Sinabung

Eruptions at Sinabung have continued and pyroclastic flows and emissions seem to have increased in intensity mid December. Ash plumes have risen in excess of 20,000 ft up to December 16th.

Shishaldin

Poor weather conditions have meant little visual conformation of the Aleutian Island volcano, however due to increased seismicity it is believed that low level lava flows continue from previous weeks. The aviation code remains at orange.

This is just a small sample of the list of volcanic activity in recent weeks, for further updates visit the Smithsonian Global Volcanism Program;

http://www.volcano.si.edu/reports_weekly.cfm

Eruption Update; Bardabunga, Mayon, Kilaeua and more

Standard

Bárðarbunga

Yes the might fissure is still going strong in the Holuhran lava field. It is now being coined as one of the largest effusive eruptions Iceland has seen in the past 150 years. In terms of lava production it is only second to Hekla’s 1947-48 13month long eruption, however this title could be taken in as little as two weeks if output continues at the rate it is now. Seismicity has decreased since August but we are still seeing low levels along the dyke and stronger quakes under Bárðarbunga particularly around the caldera rim. The Scientific Advisory Board of the Icelandic Civil Protection is still suggesting the following three scenarios are considered most likely: 

  • The eruption on Holuhraun declines gradually and subsidence of the Bardarbunga caldera stops. 

  • Large-scale subsidence of the caldera occurs, prolonging or strengthening the eruption on Holuhraun. In this situation, it is likely that the eruptive fissure would lengthen southwards under Dyngjujokull, resulting in a jokulhlaup and an ash-producing eruption. It is also possible that eruptive fissures could develop in another location under the glacier.

  • Large-scale subsidence of the caldera occurs, causing an eruption at the edge of the caldera. Such an eruption would melt large quantities of ice, leading to a major jokulhlaup, accompanied by ash fall.

SiO2 emissions are still one of the most pressing concerns for the Icelandic people. Pollution warnings are constant, and the met office has consistently tracked the SiO2 cloud which changes course with change in weather.

1. Map of current SiO2 cloud coming from the fissure site.

1. Map of current SiO2 cloud coming from the fissure site.

 

Mayon

All evidence still indicates to a potentially major eruption could occur in the next few weeks. Phivolcs has said that there has been at least five rock fall events in the past 24 hours and one volcanic tremor. Ground deformation continues with at least 3 mm of inflation recorded in the past 10 days. At times of good visibility white steam plumes are seen drifting northwest from the summit and monitors are recording SiO2 emissions at an average of  308 tonnes a day. The 6-km radius Permanent Danger Zone (PDZ) around the volcano is still in place as well as the 7-km Extended Danger Zone (EDZ) on the southeastern flank due to the danger of rock falls, landslides and sudden explosions or dome collapse that may generate hazardous volcanic flows.

For day to day bulletins visit Phivolcs; http://www.phivolcs.dost.gov.ph/index.php?option=com_content&view=category&id=70&Itemid=500008

 

Kilauea

The June 27th lava flow is still advancing albeit slowly. The HVO has said it has continued approximately 350 yards since Wednesday and is currently is 1.2 miles upslope from Apaa St. and 1.9 mils from Pahoa Village Road. Although there is no immediate threat to power lines or our facilities, Hawaii Electric light are closely following the flow and have even began installing heat resistant and dispersive materials around utility poles in the Puna area.

2. Working to protect utilities but wrapping poles in protective materials.

2. Working to protect utilities but wrapping poles in protective materials.

 

Now these are just eruptions I have so far spoken about on this page, but where else is hearing volcanic rumblings…..

Sheveluch

KVERT has reported in the past few weeks, Sheveluch in the Central Kamchatka region, has had ash explosions, incandescence, hot avalanches, as well as fumarolic activity. An ash plumes that rose 11-11.5 km (36,000-37,700 ft) after an explosion on September 24th still lingers. An ash cloud 250 by 207 km drifted NNE and the aviation code remains at orange.

 

Copahue

Sat on the Chile – Argentine boarder, Copahue experienced an intense seismic swarm on September 26th with over 140 long period events being recorded. Web cams show increased emissions; mostly white plumes, with some ash rising 200-500 m drifting SE. The aviation code remains at yellow.

Aira

JMA reported 12 explosions in the last few days of September in Aira Caldera’s Sakurajima volcano ejecting tephra as far as 1,300 m. An explosion on the 28th sent a dense ash plume 3 km in to the air. The alert level remains at 3.

 

Popocatepetl

Continuing emissions of water vapor, gas, and occasional small amounts of ash have occurred from the summit. Incandescence from the crater was observed at night. The Alert Level remained at to Yellow, Phase Two.

 

Santa Maria

On September heavy rainfall triggered a hot lahar that descended the Cabello de Ángel River, a tributary of the Nimá I river drainage on the S flank of Santa María’s Santiaguito lava-dome complex. The lahar carried tree trunks and branches, had a strong sulfur odor, and was 18 m wide and 2 m deep. During 27-28 and 29-30 September lava flows travelled down the S flank and steam plumes rose 400-500 m and drifted 600-800 m SW.

 

These just a small selection of volcanoes world wide which are showing signs of activity. As well as the 8 listed here the Smithonian Institution Global Volcanism Program lists a further 9 which show increased levels of activity thus showing how active the Earth is.

3. GVP map of volcanic activity.

3. GVP map of volcanic activity.

 

 

1. SiO2 Map; http://www.vedur.is/vedur/spar/gasdreifing Accessed 04/10/14

2. Protecting Puna; http://khon2.com/2014/10/03/hawaii-electric-lights-contingency-plans-as-kilauea-lava-approaches/ Accessed 05/10/14

3. GVP Map; http://www.volcano.si.edu/reports_weekly.cfm#vn_300270 Accessed 05/10/14

Bárðarbunga Update

Standard

It has been a while since I have given an update on the Icelandic giant, but that far from means all has been quiet across the waters, more I have been tied up with other bits.

Holuhraun lava field at night.

Holuhraun lava field at night. 12/09/14

The eruption at  Holuhraun appears to be going strong, with now an estimated 200 million cubic tonnes or more of material being erupted since the start of the fissure on the 31st August. Seismicity is still going strong in the area with most around the fissure swarming at the northern end. There is still a lot of seismicity in and around the Bárðarbunga caldera including around earthquake over magnitude 5 yesterday morning, leading people to believe a major eruption from the main vent is still possible.

2. People are still coming from all over to see observe, often from unsafe distances.

2. People are still coming from all over to see observe, often from unsafe distances.

A volcanic haze has enveloped eastern Iceland, on the 9th a Norwegian radio station even reported that the smell of sulfur could be detected along their coast line roughly 1300 km away from the eruption site. The dangerous levels of SiO2 in the air has lead to warnings being issued and locals urged to stay in doors with windows shut. Saturday night RUV reported ” unprecedented pollution levels” with atmospheric sulfur dioxide reaching a spike at 4000 micrograms/m³ (1526 ppm) around 11.00pm.

Iceland’s Met Office are suggesting one of the following are most likely to occur;

    • Subsidence of the Bárðarbunga caldera stops and the eruption on Holuhraun declines gradually.

    • Large-scale subsidence of the caldera occurs, prolonging or strengthening the eruption on Holuhraun. In this situation, it is likely that the eruptive fissure would lengthen southwards under Dyngjujökull, resulting in a jökulhlaup and an ash-producing eruption. It is also possible that eruptive fissures could develop in another location under the glacier.

    • Large-scale subsidence of the caldera occurs, causing an eruption at the edge of the caldera. Such an eruption would melt large quantities of ice, leading to a major jökulhlaup, accompanied by ashfall.

The last of these is a major cause for concern. Jökulhlaups (translates as glacial run)  is a glacial outburst flood often caused by geothermal activity and are extremely dangerous and damaging to any thing in there path.

Elsewhere in Iceland volcanic activity is also caused a stir as Gunnuhver mud pool of the Reykjanes peninsula has been cornered off as activity stepped up well beyond normal levels with boiling hot clay being thrown meters in to the air.

Figure 1. http://www.telegraph.co.uk/news/picturegalleries/earth/11090113/Icelands-Bardarbunga-volcano-spews-molten-rock-over-the-Holuhraun-lava-field.html?frame=3035222 Accessed 15.09.14

Figure 2. http://imgur.com/gallery/4oqueAj Accessed 15.09.14