GMPV
Geochemistry, Mineralogy, Petrology & Volcanology

Geochemistry, Mineralogy, Petrology & Volcanology

Ongoing unrest at Agung Volcano, Indonesia

Ongoing unrest at Agung Volcano, Indonesia

Agung volcano, a 3.1 km high cone located in the east of Bali, Indonesia, which last erupted in 1963 killing ~1500 people (Self and Rampino, 2012), is currently undergoing seismic unrest, and steam/gas emissions have been observed at the surface. This has led the Indonesian authorities to evacuate areas around Agung which could be affected by volcanic hazards, leading to the displacement of over 75,000 people.

The most likely cause of this unrest is the injection of hot, fluid magma called basalt into a cooler more viscous magma called andesite, as proposed by Self and Rampino (2012) to explain the onset of the 1963 eruption. When the basalt interacts with the cooler andesite it leads to a series of dynamical processes that release volatiles (primarily H2O, SO2 and CO2) at the surface and pressurize the magma plumbing system, resulting in strain producing seismic energy release.

Whether this leads to eruption or not depends on whether the pressure in the magma chamber can exceed the confining pressure, and produce a magma ascent to the surface. No one knows if this will happen in the next few days, but it easily could, and sooner or later there will be an eruption. The decision by the Indonesian authorities to evacuate was clearly sensible, and it appears that the local populations have been well informed on the dangers posed by Agung, helped by the living memory of the events in 1963/64. However, the normal pattern of events leading to eruption is often an exponential increasing seismic energy release, and the most recent data appear to suggest that after an initial acceleration in seismicity the system is now is a quasi-steady state, which could change very rapidly. In some ways, the best course of events would be the for the eruption to begin soon, while the alert is at maximum level and most people in potential danger have been evacuated. If there is now a pause of days/weeks without activity, there will be a growing pressure by local populations to reoccupy evacuated zones, increasing the vulnerability in case of a sudden eruption onset. Such challenges are, sadly, a fact of life for people world-wide living in the shadow of active volcanoes, and while our research makes progress in understanding the processes driving volcanic activity, we are still far from being able to provide deterministic forecasts of future eruptions.

Digital elevation model showing the major volcanic group of Bali. The conical mountain to the left is Agung which underwent a major eruption in 1963 and is currently showing signs of unrest. In the center is the complex structure of Batur volcano, showing a caldera (volcanic crater) left over from a massive catastrophic eruption about 30,000 years ago. Credit: NASA

The main hazards posed by Agung are pyroclastic flows and lahars. Pyroclastic flows have two main causes. The first cause of pyroclastic flows is the collapse of lava accumulating in the summit area, which produces a hot rock avalanche, entraining cooler air and accelerating as it flows down the flanks of the volcano. These flows can extend for several km from the summit. The second source of pyroclastic flows is eruption column collapse, when a volcanic explosion erupts a large volume of rock into the atmosphere, which then falls back down around the summit area, producing hot rock avalanches again, but this time with greater energy. This was the dominant source of pyroclastic flows in the last, 1963 eruption of Agung, producing flows to ~10 km distance from the summit, primarily to the NNE, but also to the SSW and SE. The total volume of lava and tephra (fragmented rocks in the eruption column) erupted during the 1963 eruption was ~1 km3, over a period of just under a year (Self and Rampino, 2012). Lahars are flows of mud and volcanic ash, which can be easily mobilised when freshly deposited ash is carried by the intense rains in the Indonesian rainy season. The most intense rains usually occur between November to March, so an eruption in the coming weeks could lead to lahars quite quickly. These mud flows are extremely hazardous as they can flow quickly and for long distances, scouring the land and damaging infrastructure, as well as posing a threat to life.

The probability of a large number deaths and injuries is much lower now than it was in 1963, as modern volcano monitoring techniques have improved, there is much better awareness of the hazards posed by explosive eruptions and, most importantly, local populations are better informed, with clearer communication links. About 25% of eruptions from Agung are of slightly larger magnitude (Fontijn et al., 2015), with the last eruption before 1963 occurring in 1843, producing eruption deposits approximately twice that of 1963. There have been three other, similar magnitude eruptions over the last 5000 years, but no indication of anything significantly larger. There are numerous smaller eruptions observed in the stratigraphic record. Therefore, planning for a scenario similar to the 1963 eruption with pyroclastic flow run out up to 12 km from the summit is prudent, with a good probability that the actual eruption will be smaller than that.

The north-east flank of Agung Volcano seen in 2009. Credit: Antoine Vasse Nicolas.

Apart from the local impact, an explosive eruption from Agung could affect air traffic through the dispersal of ash into the atmosphere, and climate, through the injection of SO2 and HCl into the stratosphere. The numerous active volcanoes in Indonesia produce explosive eruption that quite frequently disrupt air traffic, with the most recent events including the closure of Lombok’s Praya Airport in August 2016 due to the eruption of Rinjani volcano. The eruption of Raung in July 2015 led to the closure of airspace over Java, Sinabung in 2014/2015 affected Sumatra and Kelut effected aviation in Java in 2014. The danger posed by ash to aircraft is that the ash melts within the jet engine, and then accumulates and solidifies on a cooler rotor, eventually blocking the engine entirely. This occurred in June 1982 on a British Airways flight from Malaysia to Australia, which flew through the eruption cloud from Galunggung volcano, Java, resulting in engine failure of all four engines of the 747 jet. After numerous attempts the pilot was able to restart the engines, and the plane landed safely.

The injection of SO2 high into the atmosphere can produce climatic impacts through the generation of sulphuric acid aerosol droplets which reflect solar radiation, cooling the surface of our planet. The 1991 eruption of Mt Pinatubo in the Philippines is the most well-known example of this, producing a global cooling of 0.5 C after erupting ~18 Mt SO2 (Guo et al., 2004). The 1963 eruption of Agung erupted ~7 Mt of SO2 into the stratosphere (Self and King, 1996), and would have slightly affected climate. Stratospheric injection of HCl can produce ozone depletion, but the humid conditions of Indonesia means that the bulk of erupted HCl will be rained out.

In conclusion, the current unrest on Agung may well lead to an eruption, and it will be closely monitored by the Indonesian authorities, who have already taken preventative action by evacuating local populations. This unrest is being followed attentively by many people on twitter and other internet sources, with continuous live updates, so any change in activity will be known worldwide within minutes.

In parallel with the activity at Agung, there is also an evacuation of 11,000 people from Ambae island, Vanuatu, due to the threat posed by an eruption from Manaro Voui volcano. This important event will be the subject of a future blog post by the GMPV Science team.

Blog written by Mike Burton, GMPV President (gmpv@egu.eu), with comments from Olivier Bachmann, (Scientific Officer of the GMPV Division).

Unseen but not unfelt: resilience to persistent volcanic emissions

Unseen but not unfelt: resilience to persistent volcanic emissions

The last decade has been inundated with reports of environmental disasters impacting the lives of billions of people around the world.  While news coverage of floods, hurricanes, earthquakes or wild fires are always accompanied with spectacular images of destruction that emphasise the speed at which they strike, a myriad of slow and latent hazards have been left in the shadow of the public attention.

One of those overshadowed and underestimated hazards is environmental pollution caused by persistent volcanic emissions. Our project, UNRESP, seeks to develop early-warning procedures for events during which air pollution reaches hazardous levels, using an approach that bridges volcanology, environmental sciences, history, human geography and sociology.

 

We based our project at Masaya volcano in Nicaragua. Although Masaya has a spectacular lava lake (above video) it does not produce ash explosions, instead it quietly and persistently loads the local environment with gases and aerosol particles. This poses a huge air pollution hazard – Masaya’s annual SO2 emissions in 2006 matched those of the entire UK but were released from a point source. Masaya’s volcanic air pollution is estimated to impact at least 50,000 people in rural communities, and it is also periodically transported to the cities of Managua (population 2.2 million) and Masaya (population 150,000) where it mixes with anthropogenic air pollution.

Our interdisciplinary team, composed of researchers from the UK and Nicaragua, travelled out to Masaya this year to find out how this volcano impacts local communities. This was by no means my first trip to Masaya (it was the first volcano I visited as a PhD student a decade ago). But it was the first time I was going to concentrate on the nearby communities.

Figure 1: PM2.5 levels (daily-mean) in two communities in the vicinity of Masaya volcano, measured March – June 2017. PM2.5 pollution fluctuates greatly on short time scales and reaches ‘High’ and ‘Very high’ levels on several occasions. The air pollution index (Low, Moderate, High and Very high) is that used in the UK and is shown here for reference only as no index exists for Nicaragua.

We installed a small network of air quality monitors in the communities living near Masaya. This was the first air quality network in Nicaragua as a whole! We were able to show for the first time how the volcano impacts air quality: how intense the air pollution episodes can get, how long they last and how frequently they occur – all of these are factors that impact human mortality and morbidity. We saw that the volcano particularly enhances the concentration of atmospheric particulate (PM2.5) (Figure 1). These extremely high but short-lived pollution spikes demonstrate the need for permanent monitoring and public advisories so that their impact can be mitigated.

Figure 2: An illustration of the severe and rapid impact of Masaya’s volcanic emissions. The chain and lock had rusted within 2 weeks after installation of the air quality station.

We were also interested in more than the physical side of the hazard. We went out into local communities and tried to learn what it’s like to live every day with this volcano. We unearthed and documented a huge amount of resilience practices – little things that people do to counteract the impact of the volcano on their lives. These things may seem trivial at first glance but are based on community knowledge going back centuries. For example, the acidity of the volcanic plume causes incredibly fast rusting of metal (Figure 2) so people have learned to build houses are built without using any nails (Figure 3). Women explained how they treat their kitchen appliances in a particular way. The quality of the rain water (the acidity of which can be as low as pH 2 during the most severe pollution episodes!) is assessed by how it reacts with soap. And, perhaps most importantly, people know what kind of crops they can grow, and when. The volcanic plume is a killer to most crops (like coffee), but people have discovered that pineapple and dragon fruit grow exceptionally well.

Figure 3: Houses in El Panama village, only 2 km from Masaya’s active crater. They are built without using nails due to the extremely fast corrosion. The roofs are held in place with wood and rocks. Note that the heavy ‘cloud’ overhead is the volcanic plume.

This first ‘digging’ of our foundation phase has yielded more questions that it has answered. We are very keen to continue with our ongoing collaboration and expand it even further.

On a more personal note, the most valuable thing I learned from this trip was something that I’ve objectively always known but never felt to the same extent before. Volcanoes like Masaya are so much more than the petrology of their rocks, or the enrichment factor of their emissions, or the refractive index of their ash. They are deeply intertwined with the lives of the people around them, and to those people it’s their real life and not just a scientific publication. Let’s not ever lose sight of that.

Blog written by Evgenia Ilyinskaya (University of Leeds). You can follow the project on Twitter @UNRESPproject.

UNRESP project is funded by GCRF Building Resilience programme. Note all data discussed in this blog are unpublished and have not been peer-reviewed.

The Fractional Crystallization Freak Zone

The Fractional Crystallization Freak Zone

A large majority of igneous rocks on Earth are formed by a process known as fractional crystallization (summarized in the diagram below).

To understand this process, start by imagining a large liquid magma (melt) body. As we cool the magma, mineral phases become stable and crystals start to form. The newly formed minerals are likely to have a very different density from the magma causing them to float or sink and effectively remove themselves from the original magma body.

Diagram summarizing fractional crystallization processes in a magma chamber (see text for summary). Source Wikipedia, Author Woudloper.

 

Once removed, the minerals can no longer react with the magma and so the composition of the remaining (residual) magma changes. As the composition of the magma changes (shown by the changing colours in the diagram above) then a different set of minerals will become stable.

The pioneering work on fractional crystallization processes was done by N. L. Bowen in the early 1900’s. Bowen determined that specific minerals form at different temperatures and was able to work out the common mineral assemblage that forms from cooling magma. The minerals that make up Bowen’s ‘Reaction Series’, such as olivine, pyroxene, plagioclase, amphibole and quartz, will be known to most geologists. For the vast majority of igneous systems this model works exceptionally well to explain the changing mineral assemblage that form during cooling and depressurization.

In a few places on Earth, such as the Gardar Rift in south-west Greenland, the unique magma chemistry means that Bowen’s usual rock-forming minerals are no longer stable – and this creates some of the weirdest rocks on the planet!

The Ilímaussaq Complex (located in the Gardar Rift) is a spectacular example. Here, the magma was exceptionally rich in alkali and rare elements, and the magmatic conditions were extremely reducing. Over 225 minerals have been identified at Ilímaussaq, 30 of which were discovered there first. Some of these wonderfully wacky minerals include:

Sodalite, an extremely light (low density) mineral that comes in blue, yellow, green, and pink varieties, and also has a habit of changing color when exposed to sunlight (UV)!

Sodalite syenite composed of blue-green sodalite crystals surrounded by large (c. 10 cm) crystals of red eudialyte, black amphibole and white nepheline and feldspar. This rock crystallized in the roof of the Ilímaussaq magma chamber. Photo by Anouk Borst.

Naujakasite, a beautiful pearly lozenge-shaped mineral. Naujakasite is found nowhere else in the world, but at Ilímaussaq can make up to 75% of the rock volume!

Silver Naujakasite crystal (top left of image) from Kvanefjeld in the Ilímaussaq Complex. Source Wikipedia, Author Robert Lavinsky.

Villaumite, sodium fluoride, NaF, a particularly stealthy mineral that is only seen in freshly broken samples due its solubility in water!

Red Villaumite, NaF, from Kvanefjeld in the Ilímaussaq Complex. Photo by Will Hutchison.

Why should we care about these crazy mineral assemblages?

Well, first, they tell us about the complete range of minerals that magmas on Earth can generate. Second, and perhaps more importantly, the minerals that form in the final stages of fractional crystallization (such as steenstrupine and eudialyte) are exceptionally good at soaking up rare earth elements into their crystal structures. The rare earth elements provide vitally important hi-tech materials in our smartphones, hybrid cars and wind turbines, and so these crazy minerals, if concentrated enough, might actually be of major economic importance!

Blog written by Will Hutchison and Anouk Borst (University of St Andrews). Inspired by ongoing work of the HiTech AlkCarb Consortium.

Welcome to the new GMPV blog!

Welcome to the new GMPV blog!

Welcome to the brand-new blog for the EGU Geochemistry, Mineralogy, Petrology & Volcanology (GMPV) Division!

The aim of this blog is to provide a unique space for all mineral geeks, volcanophiles and rocking chemists to tell the world about their latest research and exciting new ideas! The GMPV Division covers a huge range of themes including: the nature, composition, structure of the Earth’s mantle; the composition, origin and evolution of the oceanic and continental crust; the formation and crystallization of magmas; the chemical compositions of igneous, metamorphic and sedimentary rocks; element transfer between the surface envelopes of the earth; volcanoes and volcanism.

This blog will feature cutting edge research and tales from field campaigns in exciting places. We hope to show off the wonderful world of magmas, rocks and minerals from the micron to the mountain scale!

We will update the blog on a monthly basis and want to bring together contributions from all GMPV scientists! In particular, early career (PhD students and postdocs) scientists (or researchers) are strongly encouraged to submit posts on GMPV themed topics or their latest paper. We will also share news, events and activities useful to the GMPV community.

The blog is managed by the GMPV Early Career Scientist (ECS) team and the editor of the blog is Will Hutchison. Please do not hesitate to get in contact with Will if you have any ideas, information or posts you would like to put forward! All contributions to the GMPV themes are welcome!

Best wishes,

THE GMPV ECS team