Tag Archives: volcanism

Volcanoes in Space

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We live on a spectacular, dynamic planet. Geological processes like volcanism and quakes were long thought to be unique to Earth, then again we once thought the planet was flat! As we further our exploration of our solar system and beyond we have witnessed that many other planets display activity from moon quakes to eruptions on distant moons of Jupiter.

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In June Venus broke in to mainstream media as the ESA announced they had evidence of current volcanic activity on the second planet from the Sun. Venus’s dense atmosphere has long been blamed on a violent eruptive past, but it was thought that this had long since calmed. Then last month NASA released images of Pluto which suggested recent resurfacing, so where is there volcanic activity within our solar system and how does it compare to activity here on Earth? Here is a basic over view of volcanology with our Solar System other than here on Earth.

Mercury

Starting with the planet nearest the  Sun with a small, quiet Mercury. When people first glimpsed at the planets scarred surface instantly it was thought that the impact from meteors or asteroids in the past were the most likely cause. Even when the suggestion was made that volcanism could be a cause for at least some of the topography it was said that the planet did not have the volatiles available for such explosions. These ideas were strongly refuted in 2008 when NASA’s MESSENGER mission began to feed back clearer images of the surface then we had before. They showed clear signs of pyroclastic deposit at 51 sites, all of which showed different degrees of erosion indicating they had happened at varying stages in the planets history. There was also evidence of compressional features such thrust faults leading us to belive that Mercury is more geologically active (or at least has been) then we previously thought.

Venus

Venus’s surface is scared with more volcanic features than any other planet in our solar system. Its dense, toxic atmosphere is believed to be due to the release of volatiles during its explosive past.Huge shields such as Maat Mons and Sapas Mons have appeared reminiscent of those of Earth such as Muana Loa with composition of lavas most likely to be a fluid basaltic or occasional carbonatite. Although some similarities are there Venus shows no sign of tectonic activity such as the liner volcanic chains or subduction arcs we have here on Earth. Volcanism appears to be limited to upwelling similar to hotspots on Earth evident in the large Hawaiian style shields.

Despite all this evidence of volcanism it appeared to have long since ceased until ESA’s Venus Express completed its 8 year mission getting up close and personal with the planet last year.

Radar imagery detected several hot spots along the surface indicating at the very least younger lava flows then we previously thought. It is still open for debate for the age of such flows or if even an eruption or two are taking place up there while I type. The one thing that Venus Express has proved is that activity has occurred in more recent geological time than we had previously thought.

The Moon

Getting closer to home we have our natural satellite, the Moon. It’s surface separated in to two distinct regions; Lunar highland and maria.  The age of the two regions were hinted at by the amount of impact scaring. The older the rock the more impact craters tend to cover its surface; the highlands. The dark patches, visible to even the naked eye, are the maria, volcanic resurfacing of these areas been they are less scared by impacts. Basaltic lava flows dated predominately at 3.8-3.2 Ga, believed to be caused by upwelling in ancient impact basins due to thinness of the crust. Unlike terrestrial basalt, samples from the Mood indicate a much lower SiO2 content (<45%).

Patches reveal recent lunar volcanism

But much like Venus, where we thought things had calmed billions of years ago, in 2014 NASA’s Lunar Reconnaissance Orbiter (LRO) allowed us to see our perception of Lunar volcanism was also potentially wrong. It was perceived volcanism came to a rather abrupt stop roughly 3.2 Ga ago but LRO was able to pick out rock formations and deposits which would not have been visible from Earth. These new features were termed Irregular Mare Patches (IMP). These new images suggest volcanism did not stop abruptly as previously thought, but petered off over millenia ending as little as 100 million years ago.Figure 4 shows one such IMP deposit called Maskelyne indicative of smaller, younger eruptions than what we believed formed the maria in the first place.

This leads to a whole new train of thought when it comes to lunar dynamics. Recent volcanism means the Moon’s interior was hotter for longer then we believed, and if so is it still capable of eruptions?

Io

Io is one of my favourite aspects of extraterrestrial volcanism, and to be fair volcanology in general. Despite only being one of Jupiter’s moons, it claims the title of our Solar Systems most volcanically active body. Io’s most famed images captured a sulphurous eruption column which breached Io’s atmosphere climbing 140 kilometres from the surface from the  Pillan Patera caldera. And also in the centre of the image the Prometheus Plume, a 76 kilometre eruption column which cast and amazing shadow of the surface. The first time the Prometheus Plume was spotted was during the Voyager flybys in 1979. It was then captured several times in exactly the same place at a similar altitude by Galileo during its orbital of Jupiter from 1995 to 2003. This suggests an eruption of continuous intensity for over 18 years!!!

Io: The Prometheus Plume

Volcanism is believed to be driven by strong tidal forces. Io is not only subject to Jupiter’s gravitational pull but also that of two of its other satellites; Europa and Ganymede, both much larger than Io. The surface is full of huge caldera’s and lava flows, much longer that we see on Earth. Magmatic composition is believed to vary from ultramafic basaltic flows to much more sulphur rich melts which lead to flows in excess of 2400  °C. It is thought that as many as 400 active volcanoes cover the surface making it a very explosive environment indeed!

Enceladus

Cryovolcanism is a concept that had been batted around for a while on form or another. A volcano erupts a melt based on the composition of the underlying crust and in some cases mantle. On Earth we have a wide variation of silica based magmas and even the rare instances of carbonatites, but what of an icey body rich in water, ammonia or methane?

When the Voyager missions passed Enceladus in the early 1980’s it was suggested that the satellite may be geologically active due to its smooth surfaces and location close to the E Ring. It wasn’t untill NASA’s Cassini mission in 2005 that proof of cryovolcanism on the body really came to light.

The first detection of the icy plume came on February 17th. Then a second event was witnessed July 14th and this time Cassini flew through the gas cloud enabling on board instruments to tell us the composition; predominately water vapour with traces of nitrogen, methane and carbon dioxide. Visual confirmation came in the November with plumes of icey particles streaming from the bodies south polar region. A subsurface ocean under the south polar region is believed to be the cause of a thermal anomaly in the area which could be fuelling volcanic activity, although tidal heating my also have a hand.

Triton

In 1989 Voyager 2 passed by Neptune’s moon Triton and took images to give us an insight to these far out bodies and managed to find further proof of cryovolcanism in our Solar System. Several geyser like eruptions were spotted with plumes as high as 8 km above the surface. The entire surface looked relatively young with such fewer impact craters than other bodies the mission had encountered, another indication it was very geologically active.

Pluto and Charon

NASA’s New Horizons mission sent back amazing images in July of not only Pluto, but also its satellite Charon. Both exhibited relatively young surfaces, Charon more so than Pluto has huge patches barely dented by impacts suggesting recent resurfacing. Pluto is home to mountainous regions which have be likened to the Earth’s Rocky’s and huge nitrogen filled glaciers. Although no clear evidence of volcanism was seen as of yet, it is obvious that Pluto is more geologically active then we previously thought. It will take another 16 months for all the data collected to return to Earth so in time we may have evidence of at least one or two more volcanic bodies within our system!

There is still much we don’t know about the dynamics of volcanoes, both here on Earth and on other planetary bodies. One thing we can conclude is the further we explore the universe the more we will learn geologically which we can apply to our own planet and equally, exploring our own planets workings can help us understand others.

Figure 1. Painting; http://www.astroart.org/#!volcanoes/c440

Figure 2. Mercury; http://space.stackexchange.com/questions/2302/how-tectonically-active-is-mercury

Figure 3. Venus poster; http://www.esa.int/spaceinimages/Images/2015/06/Evidence_for_active_volcanoes_on_Venus

Figure 4. Moon; http://www.latimes.com/science/sciencenow/la-sci-sn-moon-volcano-recent-nasa-lunar-20141014-story.html

Figure 5. Io; http://www.nasa.gov/multimedia/imagegallery/image_feature_758.html

Figure 6. Enceladus diagram; https://en.wikipedia.org/wiki/Enceladus#Cryovolcanism

Figure 7. Enceladus; https://www.pinterest.com/astrobella/volcanoes-fire-and-ice/

Figure 8. Pluto; http://www.bbc.co.uk/news/science-environment-33543383

New Decade Volcano List; #7 Mountain of Greatness

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Sadly the other week the awesome VolcanoCafe sight came under attack by an old member of the admin and was decimated. Luckily for all of us avid readers it can now be found on http://www.volcanocafe.org Now it is back  up and runnin Carl and Henrick have managed to throw up an unexpectid number 7 for their new decade volcano list. Introducing Mount Cameroon…….

Mountain of Greatness – DVP # 7

Mount Fako, old lava flows. Wikimedia Commons.

Few volcanoes on the planet represent such an awesome sight as the majestic Mount Cameroon. It stretches from the edge of the Atlantic at Bakingili Beach and reaches an astounding height of 4040 meters. Due to its prominence it is regularly dusted with snow at the top.

Mount Cameroon, or as I am used to calling it, Mount Fako, is the only volcano to date that I have worked professionally with as a geophysicist. As volcanoes go it is somewhat of a “terra incognita”, and to be quite frank, most that has been written about the volcano is just not correct. So, there is an ample chance here to set a few things straight, do some real science, and also put the limelight on one of those volcanoes of the world that is both highly dangerous and completely unmonitored.

Geologic setting

To understand Mount Fako we first must start with the geologic setting, and also come to terms with the geologic timescale of West African Volcanism. There are 3 distinct geological features that we need to contend with as we speak about Mount Fako.

The Cameroon Volcanic Line

Mount Manengouba Caldera.

The first one is the Cameroon Volcanic Line, it consists of 4 volcanic Islands, 2 large seamounts, Mount Fako itself, Manengouba, Bambouto, The Western Highland with Mount Oku, Ngaoundere, Mandara and Biu. Volcanism in the Cameroon Volcanic Line spans a time period of 49 million years and contains two distinct periods.

The first period consists of magmatic domes and maars, most of them are heavily eroded today and requires specialized knowledge to find. This period ended about 33 million years ago and can be seen as a proto-volcanic phase.

View from inside the caldera of Mount Bamboutos.

The second period started 32 million years ago at Mandara and Mount Oku. The ensuing volcanism is highly programmatic and follows a pattern where the volcanoes are born through large scale basalt eruptions creating layers between 50 and 600 meters thick. After that comes a period of trachytic lava with minor rhyolitic ignimbrites, after that comes a large caldera event with subsequent dyke formations and phreatomagmatic eruptions of diminutive scale.

The eruptive phases of the volcanoes spans from millions of years to tens of millions of years. There is no good explanation to why the basaltic eruptions during a fairly short time switch to highly explosive volcanism. My suggestions is that the large basalt flows necessitate large volume magma reservoirs that over time fills with residue from earlier eruptions and also that the magma reservoirs becomes inundated with stale base rock low in volatiles.

Mount Oku with the caldera lake.

The formation of Cameroon Volcanic Line has erroneously been attributed to a hotspot or mantleplume. And to the naked eye there seems to be a telltale track of volcanic islands and volcanoes. There is just a problem, there is definitely no hotspot or mantleplume to be had. I will though get back to this later on.

Let us start at the Northeast and work our way down to Mount Fako. The first volcano we stumble upon is Biu, very little is known about the volcano except that it morphologically follows the normal composition for a CVL volcano and that is started its activity less than five million years ago.

Mount Ngaoundere with one of the for the Cameroon Volcanic Line so common phonolitic plugs.

To the southeast comes the 32 million year old volcano of Mandara with an unstudied volcano due south. Further southeast of that unstudied volcano is the massive caldera of Nagoundere.

The group above is a distinct group of its own, not due to being morphologically different; instead they sit on a different rift system than the rest of the volcanoes. This rift system is roughly horseshoe shaped and transects the Central African Shear Zone that is home to the volcanoes below.

Annobón Island, a real tropical paradise where you can get down and dirty with your phonolite plugs.

Now it is time to continue with the Western Highlands that consists of two main volcanoes. The northernmost of those is Mount Oku that was active 31 to 22 million years ago before it went caldera forming Lake Oku. Southwest of Mount Oku we find the massive caldera of Bambouto that was active between 21 and 14 million years ago.

Next in line is the 1 million year old active volcano of Manengouba that is situated northeast of Mount Fako. It is a part of the Fako volcanic zone but is a younger and distinctly separate volcano. What makes Manengouba so interesting is that it took less than 1 million years before it went caldera.

Now it is time to get really serious with the plugs. Pico Cão Grande on Sao Tomé.

If we for now skip Mount Fako itself and jump to the other end of the CVL we find the miniscule volcanic island of Annobón and its volcano Pagalu. This diminutive Island formed during an unusually short volcanic period that started 5 million years ago and lasted less than 1 million years.

Next in line is Sao Tomé that is one large shield volcano. It started to form 13 million years ago and the volcano is still believed to be active due to the young cinder cones situated on the southeast side of the island. It is also well known for the Pico Cão Grande volcanic monolith.

Beutifal shield crater lake with a shield in the background. Pico Basile volcano on Bioko Island.

To the northeast of Sao Tomé we find the island of Principe that erupted from 31 million years ago to 14.7 million years ago.

The next island is Bioko that is housing no less than 3 major shield volcanoes that have been active historically. Volcanism here started 1 million years ago and eruptions occurred last in the 19th century.

Central African Shear Zone

All of the volcanoes from Pagalu up to that peskily unstudied volcano is situated on the CASZ, through that unstudied volcano runs the previously mentioned horseshoe shaped fault zone.

The CASZ formed around 640 million years ago and was volcanically active around that period. Previously western scientists believed that the CASZ was tectonically inactive until an M5 earthquake occurred and was monitored on a temporary seismometer. Local sources have though always stated that large earthquakes happen frequently along the shear zone, especially during eruptive phases where houses commonly have been leveled by the intense seismic activity.

The Cameroon Volcanic Line showing the CVL, the CASZ and the Benue Through. Also visible is the horseshaped fault zone. Image taken from

The CASZ was volcanically active both 640 million years ago and also 130 million years ago during the break up of Pangea.  One should note that the 3 active periods do not rule out smaller scale volcanism in between. As such the CASZ is the oldest volcanic feature on the planet that is still active.

The CASZ used to continue in the form of the Pernambuco Fault in Brazil, but as some people have noticed, the breakup of Pangea occurred and the Shear Zone ended up divided across two continents by a sizeable ocean.

Benue Through

Eruption of Cameroon in 2000. Private photograph taken from Buea.

At the same time as the single largest eruptive episode started at Paraná-Etendeka with both trap formations and the largest explosive eruptions on record the West African Craton and the Congo Craton started to separate at what is today the Benue Through.

Volcanism at Benue Through started prior to the Paraná-Etendeka event at 149 million years ago and continued for roughly 100 million years.

As the breakup of Pangea was completed the Benue Through separation of Cratons reversed and the Through started to close up, that created a heavily folded zone adjacent to the CASZ. I would seriously try to remember this feature in your mind as I get back to the hotspot and mantleplume issue.

The Hotspot

The reigning theory for the volcanism on the Cameroon Volcanic Line is that it is created by a hotspot that is travelling in an ENE direction. Only problem is that the time record does not support this at all. To be quite frank, the pattern of age of the volcanic centers is entirely random. Let us repeat the ages from north to south. 5, 32, unknown, 11, 31, 21, 1, 3, 1, 31, 14 and 5. Either I have grown dimwitted or there is just not any time sequence that is associated with a hotspot track 1 600 kilometers long.

Tomographic map of 25km depth. Do note the position of the African Superplume and keep track of it. No Visible signs of a hotspot here at CVL. Image made by DownUnder for Volcanocafé.

Some have tried to save this by surmising that there is another hotspot there and they also favor to put in influence from the Saint Helena Hotspot in the mix. It still does not blend very well with reality.

So, if the time does not indicate a hotspot, what does? Well, the temperature of the erupted magmas is quite enigmatic. The volcanoes have erupted varied temperature magmas with the heat record at 1 338C and the coldest at 1 106C with a medium temperature of 1 280. That would put it at 220C below the temperature of the Hawai’i hotspot and en par with the Icelandic Hotspot. As such that would be a fairly cold hotspot, but those exist as we know from Iceland.

Tomographic map of 25km depth. Do note the position of the African Superplume and keep track of it, also note how cold the two cratons are. No Visible signs of a hotspot here at CVL. Image made by DownUnder for Volcanocafé.

Only problem is that the hotspots of Iceland, Hawai’i and the African Plume are caused by upwelling from deep within earth and all 3 of those are clearly visible when you create tomographic charts of the mantle.

A tomographic chart shows anomalies in the speed at which sound travels after an earthquake. The most clearly visible such entities are the Icelandic Hotspot and plume upwelling and the African Plume residing under Eastern Africa. Those can be seen very deep indeed.

Tomographic map of 25km depth. Do note the position of the African Superplume and keep track of it. No Visible signs of a hotspot here at CVL. Image made by DownUnder for Volcanocafé.

Problem is just that if we go and look at the CVL we see nothing as such, actually we even find inverse anomalies at depth showing the area to be slightly cooler than expected.

The next theory is that the Benue Through is causing a localized upwelling of material from below the LAB (Lithosphere-Asthenosphere Boundary). Only problem is that this is not evident from the tomographic maps either.

Tomographic map of 200km depth. Do note the position of the African Superplume and keep track of it. No Visible signs of a hotspot here at CVL. Image made by DownUnder for Volcanocafé.

This leaves us with a conundrum. We only know that there is no hotspot causing the volcanism. We also know that the volcanism is extremely extended in time.

Volcanism is caused either by hotspots, spreading rifts like the MAR or subduction caused melt. We know that for about 50 million years there was spreading rift volcanism going on adjacent to the CVL at the Benue Through, we also know that this started after the CASZ volcanism. We also know that there historically has been no subduction going on there. Sooner or later subduction in the area will start, but we are not there quite yet geologically speaking.

Tomographic map of 300km depth. Do note the position of the African Superplume and keep track of it. No Visible signs of a hotspot here at CVL, instead the temperature is below average at the litosphere/adenosphere boundary, definitely not a Mantleplume nor a hotspot there. Image made by DownUnder for Volcanocafé.

We are here left with a 640 million year old riddle regarding volcanism. Either we are missing something, or we have a fourth form of volcanism going on at the CVL. Sadly the CVL and Mount Fako is highly understudied. This is the first reason that Mount Fako should be on the new Decade Volcano Program.

Mount Fako

Even though it is sited as being a stratovolcano Mount Fako is actually a fissure row of volcanic craters. In some respects it reminds of an effusive cousin of Iceland’s Hekla volcano in shape. Eruptions at the volcanic fissure line started 3 million years ago with large scale basalt flows that built up an elongated shield. As volcanism continued with shorter lava flows the sides have grown increasingly steeper until a steep sided elongated hull like shape formed.

As volcanism progressed the lava flows has grown increasingly volatile rich and eruptions often take place at 2 or more places. One of the sites will be high up on the volcano and will be explosive in nature and further down the fissure there will be an entirely effusive eruption causing lava flows that often reach down to the Atlantic Ocean.

The eruptions span between VEI-2 and VEI-4 with VEI-2 sized eruptions being the by far most common type.

During eruptions the volcano becomes highly seismic with extensive and intense earthquake activity that often affects the capital of the Southwest Region Buea heavily with raised houses and deaths occurring. Normally residents of Buea are forced to sleep outdoors during eruptions to not risk that their houses cave in on them.

The lavas erupted are bimodal with basalts as the main component, but the other component are trachytes and phonolites signifying a volcano containing more evolved lavas in an intermediary stage. The sheer size of the 1 400 cubic kilometer volcano, the unstable flanks and the evolving magmas, point to a volcano nearing its end stage.

If we compare Mount Fako to its post caldera brethren to the northeast we can see that they reached about the same size before they went caldera. The volcano does though not yet hold evolved enough magmas to form ignimbrite flows.

The main forms of hazard are through seismicity and flank collapses. For flank collapses the cities of Buea and Limbé are in the strike distance. The gravest danger of this volcano is though not through an explosive eruption.

Instead the gravest risk is that a large basalt flood event will occur like the one that was potentially witnessed by Hanno the Navigator 450 BC. Another large effusive eruption would not kill people directly, instead gas content and destruction of cities and farms would cause the death toll.

Mount Fako is today not monitored at all. There is no active Seismometer, no GPS, no Inclinometer. Instead the park rangers are tasked with observing what is going on visually and forward the information to anyone interested in knowing it.

Together with the risk to the large local population and the scientific conundrum that Mount Fako poses it clearly merits to be placed at place number 7 on our proposed new Decade Volcano Program.

CARL (text) & DownUnder (tomography)

http://www.volcanocafe.org/science/mountain-of-greatness-dvp-7/

The Decade Volcanoes

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As I reblogged my last post, a revision of the Decade volcano list by the authors of VolcanoCafe, I thought before I bring you the new list I should really explain what the original one actually was!

As mentioned in one of my earliest articles, the list was complied in 1990 by the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) a nongovernmental society. The aim was to select the worlds most hazardous volcanoes and put measures in place to keep a closer eye on them and raise awareness across the globe on the threats they pose, for a decade (1991-2000 The UN’s International Decade of Natural Disaster Reduction). Based on varied criteria from historic eruptions to local populations, the following made the cut;

Figure 1. USGS map of the decade volcanoes.

15 Years on the list is still going all though monitoring in some areas may have slackened slightly. It has seen some success such as the diversion of a lava flow on Etna back in 1992 and has helped form a better understanding of phreatic eruptions on Taal. It has sadly also come at great loss on several occasions as well. Despite increased monitoring of Unzen in 1991 pyroclastic flows killed 43 including volcanologists Katia and Maurice Krafft and Harry Glicken.  And even closer to the project, in 1993 the Decade Volcano conference took place in Pasto, Columbia an expedition from the conference to the Galeras crater occurred on February 14th when the volcano suddenly erupted. 3 tourists and 6 volcanologists including Professor Geoff Brown, Head of Department of Earth Science at the Open University, all lost their lives.

Many volcanologist are sceptics and/or critics of the program, hence the call for a revamp. Personally I feel any thing which promotes volcanic awareness is great all though there are some which need much more than others. Volcanoes are ever evolving and unlike most geological features can change in minutes rather than millennia and therefore prehaps a decade is too long for reviews of such a program. I know which have made my list, it will be interesting to see what makes the cut for the guys at VolcanoCafe!

Figure 1. http://listas.20minutos.es/lista/volcanes-de-la-decada-decade-volcanoes-301649/

OUGS Talk; John Murray on Etna

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One of the perks of studying geoscience with the Open University is it has a very active Geological Society. Although I joined and went to the odd talk towards the start of my degree, as with many other things, life gets in the way. When I heard the speaker of April’s meeting though it was impossible to not jump at the chance to go….

Figure 1. Mount Etna with the city of Catania in the foreground

On my trip to Masaya back in February I had the privilege of working with John Murray, Visiting Research Fellow at the Open University. A geophysicist, he has worked predominantly on Mount Etna for over forty years. In that time monitoring techniques have moved on greatly, as has much else with the development of technology. This however does not mean proven techniques are not equally, and in some cases, more effective than the new. John specialises in leveling, dry tilt and more recently GPS monitoring of Etna which gives us high precision ground deformation data. For years John secured funding from NERC and many other sources to map the volcanoes deformation. In later years research has become self funded such is his drive to discover the inner workings of the Mediterranean giant.

Figure 2. A map showing the volcanoes of Italy. Etna is the only one laying of the island of Sicily.

Figure 3. John levelling on Masaya.

The other night John addressed the London branch of the Open University Geological Society (LOUGS), to tell them about his work and what he believes 45 years worth of data suggests.

Etna began to erupt roughly 300,000 years at the Val Calanna centre south-west of current activity. Subsequent activity moved on to theTrifoglietto 1 and the Trifoglietto 2 centres before its current position about 170,000 years ago which is sometimes refered to as Mongibello as depicted in figure 4.

Figure 4. Proposed migration Etna based on previous volcanic centers

The Valle Del Bovo is a prominent feature on Etna. The U-shaped depression many believe depict structural failures of the flank along the line of migration of volcanic centres. What John has suggested based on his high precision mapping is that it is not the magma source that is moving but the topography which is slipping seaward.

Also as ground deformation does not following Mogi models (a mathematical model which links changes within a magma chamber to topographical changes), it is being suggested that Etna does not have an appreciable magma chamber, rather taking its material straight from the mantle like a hot spot. This idea is chemically supported by the fact the main igneous rock produced by Etna is Hawaiite; which is compositionally similar to mantle rock.

John is yet to publish his findings in full so I won’t give away any more. It’s safe to say though it is sure to change our views of Etna’s dynamics. John’s passion in his quest to uncover Etna’s secrets is truly inspirational, especially to an aspiring volcanologist like myself. I can’t wait to work on her flanks with him next August.

Figure 5. Eruption February 23rd 2013.

Figure 1; http://en.wikipedia.org/wiki/Mount_Etna

Figure 2; http://www.understandingitaly.com/profile-content/volcanoes.html

Figure 3; Authors own.

Figure 4; http://astrolabio.amicidellaterra.it/node/329

Figure 5; http://mountetnamaddison.weebly.com/eruptions.html

Eruptions Updates

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Villarrica, Chile

Villarrica has become the Kim Kardashian of volcanoes with stunning images of its recent activity flooding the internet. Fire fountains have sent ash and lava up to 1000 ft in to the air and light up the skies of Southern Chile for the past few days.

The volcano has been restless for several weeks now, with small bombs and scoria blocking the usual tourist hike round the crater lake. So far about 3,500 people have been evacuated from the flanks, predominantly the residents of Pucón a popular tourist destination.

Although the fireworks appear to have calmed down, seismicity remains high indicating Villarrica has not finished clearing his throat.

Bardabunga, Iceland

The other big volcanic news this past week comes with the end of the blogs most covered lava field at Holuhraun. On February 29th the Icelandic Met Office released a statement that the fissure eruptions has come to an end as there appears to be no lava output since mid February.

 

More in depth updates soon to follow.

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

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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

Current Volcanic Activity; New and Updates.

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Sinabung

Just moments after posting this originally images came through of a pyroclastic flow at Sinabung at 14.05 GMT.
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Fogo

Finally I have found a half decent update from the Global Volcanism Program albeit for about a week or two ago. By the 6th January the lava front had stalled in areas near S Ilheu de Losna where as was still advancing at a slow rate in the northern end of the town. Houses are still being overtake by the flow but decreasing temperatures of the lava means we could be nearing an end to the destruction. For the first few days of the month sulfur dioxide emissions were averaging at 1200 to 1300 tonnes a day.

Etna

Etna saw out 2014 with some pretty explosive activity on the 29th December. The new southeast crater had consistent but small emissions and incandescents. Explosions intensified on the 2nd and 3rd sending material 150 meters above the crater rim and an ash plume which traveled southwest.

Activity has been pretty on going since December 28th and shows little sign of slowing. On January 1st and 2nd, strombolian activity was seen at th Voragine crater, which has been inactive for over two years.

HungaTonga-HungaHa’apai

Based on pilot observations an ash plume rose to just over 10,000 ft on January 6th.  This is the first notable activity at the volcano since 2009. The main caldera is submarine.

Soputan

Darwin VAAC reported that a ‘significant’ eruption began at 14.47 local time on January 6th.  A lava flow has travelled 2 km down the WSW flank although no warnings have been issued. An ash plume rose to roughly 27,000 ft how ever nothing can be detected on satellite imagery due to poor weather conditions. The alert remains at 3 on the four point scale.

Bárðarbunga

As of January 5th the lava flow now covers an area just over 83 square kilometers. although the overall intensity of both flow and seismicity is less then a few months ago, the fissure eruption shows no sign that it is coming to an end.

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Tangkubanparahu

On December 31st the alert d 2 and local residents were warned not to go within a 1.5 km radius of the crater. White plumes has been drifting from the Ratu crater since late November, but an increase in seismicity and ground deformation has led to the apparent rise in threat.

Sheveluch

KVERT reported a lot of strong activity at Sheveluch towards the end of December including incandescent avalanches and fumerolic activity. The aviation code was kept at orange as an ash plume travelled both 60 km westwards and over 370 km ENE. Satellite images indicate a thermal anomaly over a new lava dome on the northern flank.