Volcanoes of the Ethiopian Rift Valley

The great Rift Valley of Ethiopia is not only the cradle of humankind, but also the place on Earth where humans have lived with volcanoes, and exploited their resources, for the longest period of time. Perhaps as long ago as 3 Million years, early hominids began to fashion tools from the volcanic rocks from which the Rift Valley was floored, including basalt and obsidian.

View into the Main Ethiopian Rift Valley, on the descent from Butajira to Ziway. Aluto volcano in the centre distance.

The Ethiopian Rift Valley is just one part of the East African Rift system – the largest active continental rift on Earth. While the Ethiopian rift hosts nearly 60 volcanoes that are thought to have erupted in the past 10,000 years, there is only very sparse information about the current status of any of its ‘active’ volcanoes. There are historical records for just two or three eruptions along the MER: 1631 (Dama Ali), and ca. 1820 (Fantale) and (Kone). In contrast, the Afar segment of the rift includes one volcano known to have been in eruption almost continuously since 1873 (Erta Ale), and several other volcanoes that have had major recent or historical eruptions (Dubbi 1400 and 1861; Dabbahu, 2005; the Manda Hararo Rift, 2007, 2009; Dallafilla, 2008, and Nabro, 2011). So are the volcanoes of the MER simply declining into old age and senescence? Or do they continue to pose a threat to the tens of millions of people who live and work the land across this vast region?

Panorama of Lake Shala, part of which fills the huge caldera of O’a volcano.

To address this question, and others, the NERC funded RiftVolc consortium is carrying out a broad-scale investigation of the past eruptive histories, present status and potential for future activity of the volcanoes of the Central Main Ethiopian Rift. This spans eleven known or suspected centres, several of which have suffered major convulsions of caldera-collapse and eruption of great sheets of ignimbrite across the rift floor in the distant past. The first challenge is to piece together the eruptive histories of these volcanoes over the past few tens of thousands of years, and this is something that starts with fieldwork designed to detect the traces of these past events in the rock record. The RiftVolc field team, led by post-doctoral researcher Karen Fontijn, and with doctoral students Keri McNamara (Bristol) and Ben Clarke (Edinburgh) and masters students Amde and Firawalin (AAU) are spending the next five weeks completing a rapid survey of the volcanic ash and pumice deposits preserved within the rift.

Panorama of the eastern caldera of Corbetti volcano.

The first challenge is to identify the tell-tale clues that the sequences of young rocks, soils and sediments contain volcanic deposits. Close to the volcano, we might expect an individual large explosive eruption to leave both thick and coarse deposits; but go too close to the volcano, and there may be so much volcanic material that it can become hard to identify the products of single significant eruptions, as opposed to the ‘background noise’ of smaller but more frequent eruptions.

Karen and Keri examining the young pyroclastic rocks of Corbetti volcano

Out on the flanks of the volcano and beyond, we have the vagaries of geological preservation (did the pumice or ash land somewhere where it would then stay unmodified?) and erosion and weathering (removing or modifying the evidence) to contend with. Each of these factors will depend not only on the nature of the original deposit (how thick it was; what it was made from); but also on the environment in which the deposit formed (on a lake bed? the open savannah?  a forest? On a slope, or not?), and on the subsequent history of that environment (did the lake dry out, or continue to fill with sediment? Did the pumice become stabilised in the grass land; or did it get blown or washed away? How quickly did the soil and vegetation recover after the eruption? How deeply has weathering penetrated in the intervening millennia since the eruption?). Lots of questions to ponder!

Shelly fossils from an ancient lake deposit, interbedded with pumice layers from Aluto volcano

Our long-term goal is to better understand what sort of hazards the Rift’s volcanoes pose to those who live on and around them. There are, of course, much greater immediate challenges to communities in the region linked to the competition for the natural resources (water, land) in this region; but the rapid development of geothermal prospects in the Rift does mean that we need to pay closer attention to the state of the volcanoes that are the source of the geothermal heat.

Fresh road cut section through an obsidian lava dome and drape of pyroclastic rocks, on the way to Urji volcano and Corbetti’s new geothermal power plant

Aside from the volcanoes, the main Ethiopian Rift and its lakes make for a spectacular environment to work in. Despite receding lake levels and failing rains this year, there are vibrant patches of forest and a host of exotic birds and animals to enjoy.

Pair of little bee eaters, Lake Awassa

Flock of flamingo, Lake Chitu

Marabou stork, Lake Ziway

 

 

 

Camels eating Prickly Pear cactus, Corbetti

Ethiopian Fish Eagle, Lake Ziway

Acknowledgements. RiftVolc is a NERC-funded collaborative research project. Many thanks to our Ethiopian collaborators at the Addis Ababa University School of Earth Sciences and the Institute of Geophysics, Space Science and Astronomy (IGSSA) for hosting us and facilitating the joint field campaign; and to Ethioder for providing field vehicles and excellent drivers.

Advertisement

Undergroundology at the Oxford University Museum of Natural History

Source: Undergroundology at the Oxford University Museum of Natural History

The Mexico City earthquake, 19 September 1985

As a volcanologist based in the UK, I am in the privileged position of rarely being affected by the natural events that I study. And, although I have worked for extended periods of time in earthquake-prone regions, I have never experienced anything more than the gentle nudge of a small tremor.

Thirty years ago, shortly after 7 am local time on 19 September 1985, Mexico City was struck by a large earthquake. The epicentre was near the Pacific coast, and the main event had a magnitude of 8 – just a little less than the September 2015 Illapel earthquake in Chile. Listening in the UK to BBC reports, it soon became clear that there was a terrible disaster unfolding – even though the conurbation was hundreds of kilometres from the epicentre, there was considerable damage to hundreds of buildings across the city. Later analysis revealed an unusual feature of the damage – most of the buildings that collapsed were 5 – 20 stories high; while the majority of both shorter, and taller, buildings were undamaged. This feature arose from the local geology – much of the city is built across old lake deposits. The layer of lake sediments acted to amplify the ground motion as the seismic waves passed by, leading to strong accelerations, and a characteristic period of around 2 seconds. Buildings with a natural period of vibration close to 2 seconds would have begun to resonate, and eventually fail catastrophically, as the strong shaking continued for several minutes. The result of this was a shocking pattern across the city of collapsed buildings cheek by jowl with others that showed no signs of damage.

Among the many thousands who lost their lives were several British language students, who had just arrived in Mexico City on their way to their ‘year abroad’ teaching assignments across Latin America. One, Helen Cawthray, was a linguist at St Catharine’s College, Cambridge; a contemporary and friend of mine. Another, Susan Mell, was a linguist at St Anne’s College, Oxford, where I now teach Earth Sciences. A poignant reminder not only of the random element of disasters, but also of their global reach. As we look back on the thirty years that have passed, the question remains: have the lessons been learned? Or might it all happen again?

Maria Graham, and a large earthquake in Chile, 1822

As news comes in of another very large earthquake in Chile – the third magnitude 8 earthquake along Chile’s Pacific margin in the past six years – this is a stark reminder of the destructive potential of these extreme natural events. These days we are used to the rapid, or near-real-time diffusion of news as these events unfold – in this case, as the tsunami ran along the Chilean coast, and propagated across the Pacific ocean. First indications are that the region that ruptured during the earthquake was a large section of the subduction zone plate boundary where the Nazca tectonic plate is sliding beneath the South American plate; close to an area that previously ruptured in great earthquakes in 1943, 1906, 1880 and 1822.

Map of historical rupture zones of large Chilean earthquakes. The red dots show the locations of the 16 September 2015 earthquake and early aftershocks. Source: United States Geological Survey.

One of the earliest first-hand accounts in English of a large earthquake in this part of Chile comes from the writings of Maria Graham, who was living near Valparaiso in 1822; close to the source of the great earthquake of 19th November 1822, and within the region that was most hard hit by the event. Her journal – published in 1824 – records the event in great detail; and in particular, describes the dramatic coastal uplift that occurred as an immediate consequence of the event. A version of her report was later read to the Geological Society of London, where it caused a good deal of interest and, later, controversy.

View from Maria Graham’s house. Bodleian libraries, Oxford, 4° R 56 Jur

Excerpts from Maria Graham’s ‘Journal of a residence in Chile, during the year 1822; and a voyage from Chile to Brazil, in 1823’,  London, 1824

November 20th, 1822.

‘At a quarter past ten [in the evening], the house received a violent shock, with a noise like the explosion of a mine. I sat still.. until, the vibration still increasing, the chimneys fell, and I saw the walls of the house open.. We jumped down to the ground, and were scarcely there when the motion of the earth changed from a quick vibration to a rolling like that of a ship at sea. The shock lasted three minutes. Never shall I forget the horrible sensation of that night. [Back in the house] I observed that the furniture in the different rooms .. Had all been moved in the same direction, and found that direction to be north-west and south-east.

Mr Cruikshank has ridden over from old Quintero: he tells us that there are large rents along the sea shore; and during the night the sea seems to have receded in an extraordinary manner, and especially in Quintero Bay. I see from the hill, rocks above the water that never were exposed before.

On the night of the nineteenth, during the first great shock, the sea in Valparaiso bay rose suddenly, and as suddenly retired in an extraordinary manner, and in about a quarter of an hour seemed to recover its equilibrium; but the whole shore is more exposed and the rocks are about four feet higher out of the water than before.‘

View of Quintero Bay, drawn by Maria Graham. Bodleian libraries, Oxford, 4° R 56 Jur.

December 9th, 1822.

‘in the evening I had a pleasant walk to the beach with Lord Cochrane; we went chiefly for the purpose of tracing the effects of the earthquake along the rocks. On the beach, though it is high water, many rocks with beds of muscles remain dry, and the fish are dead; which proves that the beach is raised about four feet at the Herradura. Above these recent shells, beds of older ones may be traced at various heights along the shore; and such are found near the summits of some of the loftiest hills in Chile.‘

In her journal accounts, Graham went on to speculate that repeated earthquakes could be responsible for the general elevation of land, and the building of mountains, in places like the Andes; themes that were later taken up by Charles Lyell, and then Charles Darwin – who was in Chile 13 years later, where he experienced the 1835 Concepcion earthquake firsthand.

Links

IRIS Special Event Page, Illapel – great collection of resources on the Illapel earthquake

United States Geological Survey – Illapel earthquake information

The Maria Graham Project, Nottingham Trent University

Profile of Maria Graham on TrowelBlazers

Energy Poverty and Geothermal Energy Futures

Ethiopia is one of the most impoverished nations in the world, in terms of the number of people who live without access to electricity. The World Energy Outlook reported that in 2014, 70 million people in Ethiopia, or 77% of the population, have no access to electricity. Ethiopia is also one of the more volcanically-active regions of the world, with 65 volcanoes or volcanic fields that are thought to have erupted within the past 10,000 years – though few of these volcanoes have been studied in any detail; and fewer still are closely monitored.

Geothermal power plant infrastructure at Aluto volcano, Ziway, Ethiopia.

One benefit of this abundance of young volcanoes is that the geothermal energy potential of the region is significant – offering the potential of accessible and renewable low-carbon energy. Further south, along an extension of the Great Rift Valley, Kenya is already taking steps to exploit geothermal energy, with an installed capacity by December 2014 of 340 MW and an ambition to increase this by at least an order of magnitude within the next 15 years. In Ethiopia, current capacity currently stands at around 7 MW – provided by the Aluto Langano Power Plant, which was the first operational geothermal power plant in the country. In Ethiopia, as in Kenya, there is considerable ambition to develop geothermal power further – with the several volcanic centres identified as having the potential to supply 450 – 675 MW by 2020. In a country where per-capita electric power consumption is just 52 kWh (100 times less than that in the UK), that’s a lot of new energy.

Entrance to the Ethiopian Electric Power Corporation Aluto Langano Geothermal power plant, in the centre of Aluto volcano, Main Ethiopian Rift Valley.

All of this interest in young volcanoes as potential sources of ‘clean energy’ provides a significant opportunity for geoscientists to try and find out a little bit more about their eruptive past, and their potential for future activity; and to work out where the hot fluids and gases that provide the geothermal prospect are stored within the crust.

Using a PP systems respiration chamber to measure the escape of CO2 from the ground surface across the volcano.

At Aluto volcano, work by Will Hutchison using imagery from an aircraft survey (to identify young faults and fractures), and a ground-based survey of where (natural) carbon dioxide is seeping out of the volcano at the present day, has helped develop a cartoon ‘model’ for this volcano. Our current view is that Aluto volcano currently leaks quite small amounts of heat and gas to the surface; mainly along long-lived fractures and faults, some of which have origins older than the volcano itself. Inside the volcano, fluids are trapped under layers of impermeable rock – perhaps two to three kilometres below the surface – where they are heated by the warm rocks of the volcanic hearth.

 

Planned drilling campaigns on Aluto, and on the neighbouring volcano and geothermal prospect, Corbetti, should eventually fill in some of the gaps in our geological knowledge; and help to transform the energy futures of some of the millions of people who live along the Ethiopian Rift valley.

References

Hutchison, W., T. A. Mather, D. M. Pyle, J. Biggs, G. Yirgu, 2015, Structural controls on fluid pathways in an active rift system: A case study of the Aluto volcanic complex. Geosphere, 11, 542-562, DOI:10.1130/GES01119.1 [Open Access]

Kebede, S., 2012, Geothermal Exploration and Development in Ethiopia: Status and Future Plan, in: Short Course VII on Exploration for Geothermal Resources, 14 pp.

Data Sources 

World Bank – Electric Power Consumption

World Energy Outlook, Africa

Volcán Calbuco: what do we know so far?

Image of Calbuco volcano on April 24, 2015, from NASA’s Earth Observatory. Natural colour image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite. The narrow plume of ash and gas is being blown to the East, away from Calbuco and towards the town of San Carlos de Bariloche.

Detailed assessments of what happened during the April 22-23 eruption of Calbuco, Chile, are now coming in from the agencies responsible for the scientific monitoring of the eruption (SERNAGEOMIN) and for the emergency response (ONEMI). The volcano is well monitored and accessible, and as a result there has been a great deal of high quality information, and imagery, made available very quickly. In addition, there is a wealth of satellite remote sensing data, which together allow us to collect up some basic statistics about the scale of the eruption. So here are some summary statistics for now:

1. This was the first explosive eruption of Calbuco since a small eruption that lasted 4 hours on 26 August 1972. In the intervening 42 years, there was an episode of strong ‘fumarole’ emission in August 1996, but no recent signs of unrest.
2. The eruptions of 22-23 April began with little prior warning, and both formed strong, buoyant plumes of volcanic ash that rose high into the atmosphere – captured in some of the most amazing video and timelapse footage of an eruption anywhere in the world. The first eruption started at 18:05 (local time)  on 22 April; the ash column rose to 16 km, and ejected 40 million cubic metres of ash in about 90 minutes. The second eruption began after midnight (01:00 local time, on 23 April), with an ash column that rose to 17 km, and ejected 170 million cubic metres of ash over 6 hours. Based on the volume of material erupted (0.2 cubic km), and the eruption plume height, the combined phases of the eruption can be classified as a VEI 4 event, with an eruption magnitude of 4.4 – 4.6 (depending on the assumed density of the deposits).
3. The Calbuco eruption was the third large eruption in this region of Chile in the past 10 years; but 4 or 5 times smaller than the eruptions of Chaiten (2008) and Puyehue Cordon-Caulle (2011).
4. At its greatest extent, the ash cloud covered an area of over 400,000 square kilometres, affecting a population of over 4 million people in Chile and Argentina (modelled using CIESIN). Ash fallout was reported from Concepcion, on the Pacific coast, to Trelew and Puerto Madryn on the Atlantic coast of Argentina.
5. The magma involved in the eruption was a typical andesite/dacite, containing volcanic glass and crystals of plagioclase and amphibole, with minor quartz and biotite.
6. The SO2 gas release from the eruption was substantial – around 0.2 – 0.4 Million tonnes – probably some way short of the levels needed to have a significant impact on the climate system.
7. The eruption was accompanied by dramatic pulses of lightning (a common feature in volcanic eruptions), and easily visible from space.
8. At least 6500 people were evacuated as a result of the activity. The nearby town of Ensenada was badly affected by thick pumice and ash deposits, and lahars pose continuing hazards in the drainages that run off Calbuco, and into nearby lakes (Llanquihue, Chapo). The eruption has strongly affected some of the salmon fisheries in the region. Downwind, air transportation has been disrupted in Chile, Argentina and Uruguay.
9. At the time of writing, SERNAGEOMIN note that the seismic activity has diminished somewhat , but the volcano remains at a red alert.

Taking the pulse of a large volcano: Mocho-Choshuenco, Chile

As the recent eruptions of Calbuco and Villarrica in southern Chile have shown, the long arcs of volcanoes that stretch around the world’s subduction zones have the potential to cause widespread disruption to lives and livelihoods, with little or no warning. Fortunately, neither of these eruptions has, so far, led to any reported loss of life – but the consequences  of these eruptions for the communities living within reach of the ash plumes and beyond will continue to play out for months or years into the future.

The young cone of Mocho volcano, southern Chile, which may have erupted as recently as 1937. Mocho-Choshuenco volcano is one focus of our ongoing work in the region.

We have been working in southern Chile for a few years now, helping to extend what is known about past explosive eruptions at some of the region’s most active volcanoes. In this part of Chile, the written records of past eruptions only extend back a few hundred years – at the most – so most of our work has involved digging into the geological records of the region, to try and piece together the fragmentary stories of past eruptions. This can be slow and painstaking work, both in the field and in the laboratory, but is always exciting when things start to come together.

Field sampling on Mocho-Choshuenco volcano: deposits of the ‘Enco’ eruption.

This week, Harriet Rawson has published her first major scientific paper on the volcanic eruption history of Mocho-Choshuenco over the past 18,000 years. The 18,000 year timescale spans the volcanic activity that has taken place since the end of the last ice age; and we can be fairly confident that by visiting hundreds of sites around the volcano, we have found most of the ‘major’  eruptions, and many of the ‘moderate’ explosive eruptions from this volcano over this time period. The results of Harriet’s work are summarised in the picture below – which shows the timing, composition and sizes of eruptions through time. Just for context, the March 3 eruption of Villarrica was small (10 million cubic metres of ash, or magnitude 3 on the y axis), with a composition represented by an orange colour (so a bit like the Mocho eruptions around 4,000 years ago); while the April 22 eruption of Calbuco was moderate (210 million cubic metres of ash, or magnitude 4.5 on the y axis), and a composition in the green to pale blue range (like the eruption around 2000 years ago).

The record of explosive volcanic eruptions at Mocho-Choshuenco volcano over the past 18,000 years (from Rawson et al., 2015). The x axis shows time, as ‘thousands of years before present’, based on radiocarbon dating of flecks of charcoal preseved within the deposits. The y-axis shows the ‘size’ of the eruption, in terms of the eruption magnitude, which is a logarithmic scale of erupted mass or volume of ash and pumice. The coloured curves represent the age and erupted composition of the volcanic events that have been recognised – with the ‘peak’ of the curve showing the best estimate of the eruption age, and size. The width of the curve gives an indication of the uncertainty in the timing of the eruption. The cartoon parallel to the x-axis shows how regional climate and ice cover at the volcano are thought to have changed over the same time period.

In many ways, this work is just the start of the forensic process of understanding how this particular volcano works and of the threats it might pose for the future;  but it is also a critical piece of the jigsaw in terms of understanding the pulse of the volcanic arc, and crossing the gap between the geological past, and the volcanic present.

The wonderful ‘Salto Huilo Huilo‘ in the Huilo Huilo ecological reserve, at the foot of Mocho-Choshuenco.

Acknowledgements

This work has been funded primarily by the UK Natural Environment Research Council, and represents the outcome of many years of collaborations with colleagues from the Chilean Geological Survey, SERNAGEOMIN, with field work in the region supported by numerous colleagues and assistants, and with the support of CONAF and Reserva Huilo-Huilo.

References

K Fontijn et al., 2014, Late Quaternary tephrostratigraphy of southern Chile and Argentina, Quaternary Science Reviews 89, 70 – 84. [Open Access]

H Rawson et al., 2015, The frequency and magnitude of post-glacial explosive eruptions at Volcan Mocho-Choshuenco, southern Chile. Journal of Volcanology and Geothermal Research, doi:10.1016/j.jvolgeores.2015.04.003 [Open Access] Datasets available on figshare.

DM Pyle, 2015, Sizes of volcanic eruptions, Chapter 13 in Sigurdsson et al., eds, Encyclopedia of Volcanoes, 2nd edition, pp 257-264. doi:10.1016/B978-0-12-385938-9.00013-4

Calbuco erupts. April 22, 2015.

Volcan Calbuco, which burst into eruption on April 22^nd, is one of more than 74 active volcanoes in Southern Chile that are known to have erupted during the past 10,000 years. Unlike its photogenic neighbour, Osorno, Calbuco is a rather complex and rugged volcano whose eruptive record has posed quite a challenge for Chilean geologists to piece together.

Volcan Calbuco (foreground), viewed on approach to Puerto Montt airport

Calbuco’s volcanic neighbours, Osorno and Tronador.

The little that we do know about Calbuco’s eruption history comes from two sources: historical observations, and geological/field investigations. The historical record is not well known – other than that it has had repeated eruptions since the late-19^th century. The eruption record prior to this is much less well known from written records, although the region has been populated for several millennia. The most spectacular recent eruption was in 1961, that ranked ‘3’ on the Volcanic Explosivity scale (VEI).

One interesting feature of Calbuco is that it is the only volcano in the area that regularly erupts magmas of an ‘intermediate’ composition (andesite), that contain a distinctive hydrous mineral, amphibole. This should make the eruptive products – particularly the far-flung volcanic ash component – quite distinctive. Preliminary work has identified the deposits of at least 13 major explosive eruptions from the past 11,000 years along the Reloncavi Fjord; but none of these have yet  been found further afield, even though they were the products of strong explosive eruptions (certainly up to VEI 5).

Calbuco is one of the many volcanoes in southern Chile that come under the watchful eye of the volcanologists from the Chilean Geological Survey, SERNAGEOMIN, and their Observatory of the Southern Andes (OVDAS); follow @SERNAGEOMIN for updates as the eruption progresses.

Further Reading

Find out more about our ongoing work on the volcanoes of Southern Chile

Fontijn K, Lachowycz SM, Rawson H, Pyle DM, Mather TA, Naranjo J-A, Moreno-Roa H (2014) Late Quaternary tephrostratigraphy of southern Chile and Argentina. Quaternary Science Reviews 89, 70-84. doi 10.1016/j.quascirev.2014.02.007 [Open Access]

Moreno, H., 1999. Mapa de Peligros del volcán Calbuco, Región de los Lagos. Servicio Nacional de Geología y Minería. Documentos de Trabajo No.12, escala 1:75.000.

Sellés, D. & Moreno, H., 2011. Geología del volcán Calbuco, Región de los Lagos. Servicio Nacional de Geología y Minería, Carta Geológica de Chile, Serie Geología Básica, No.XX, 30 p., 1 mapa escala 1:50.000, Santiago

Sellés, D et al., 2004, Geochemistry of Nevado de Longaví Volcano (36.2°S): a compositionally atypical arc volcano in the Southern Volcanic Zone of the Andes, Revista Geologica de Chile 31.

Watt SFL, Pyle DM, Naranjo J, Rosqvist G, Mella M, Mather TA, Moreno H (2011) Holocene tephrochronology of the Hualaihue region (Andean southern volcanic zone, ~42° S), southern Chile. Quaternary International 246: 324-343

Watt SFL, Pyle DM, Mather TA (2013) The volcanic response to deglaciation: Evidence from glaciated arcs and a reassessment of global eruption records. Earth-Science Reviews 122: 77-102

The great eruption of Tambora, April 1815

Map of the Sanggar peninsula, on the island of Sumbawa, Indonesia, and the crater of Tambora. From Heinrich Zollinger’s 1847 expedition to the crater, published in 1855. From University of Oxford, Bodleian Library Collection.

April 2015 marks the 200th anniversary of the great eruption of Tambora, on Sumbawa island, Indonesia. This eruption is the largest known explosive eruption for at least the past 500 years, and the most destructive in terms of lives lost, even though the precise scale of the eruption remains uncertain. The Tambora eruption is also one of the largest known natural perturbations to the climate system of the past few hundred years – having left a clear sulphuric acid ‘fingerprint’ in ice cores around the world, and evidence for a strong causal link to the ‘year without a summer‘ of 1816, and global stories of inclement or unusual weather patterns, crop failures and famine.

Much of what we do know about the eruption and its local consequences is down to the efforts of two sets of people: Stamford and Sophia Raffles; and Heinrich Zollinger. In 1815, Thomas Stamford Raffles was temporary governor of Java; the British having invaded in 1811. Shortly after the eruption of Tambora, he gathered reports from people in areas affected by the eruption, and put these together in an ‘account of the eruption of the Tomboro mountain‘, which was published first in 1816 by the Batavian Society for Arts and Sciences, and later published posthumously by his wife, Lady Sophia Raffles, in her biography of his life and works (Raffles, 1830).

There is a considerable scientific literature (see references below) which has documented the main phases of the eruption, which began in earnest on April 5, 1815, and built to an eruptive climax on 10 – 11 April 1815. It is thought that the volcano had been rumbling for some time prior to this, perhaps as early as 1812; and some of the contemporary records collected by Raffles suggest that the first ashy explosions may have begun by about April 1, 1815. An extract from a letter from Banyuwangi, Java, 400 km west of the Sanggar peninsula, describes this stage of the activity:

‘At ten PM of the first of April we heard a noise resembling a cannonade, which lasted at intervals till nine o’clock next day; it continued at times loud, at others resembling distant thunder; but on the night of the 10th, the explosions became truly tremendous. On the morning of the 3rd April, ashes began to fall like fine snow; and in the course of the day they were half-an-inch deep on the ground. From that time till the 11th the air was continuously impregnated with them to such a degree that it was unpleasant to stir out of doors. On the morning of the 11th, the opposite shore of Bali was completely obscured in a dense cloud, which gradually approached the Java shore and was dreary and terrific.‘

Heinrich Zollinger’s map of the inferred distribution of volcanic ash that fell across Indonesia following the eruption of Tambora in 1815. This may be the first example of an ‘isopach’ map of ash fallout from any volcanic eruption. From University of Oxford, Bodleian Library Collection.

The climactic phase of the eruption was very clearly described in an account by the Rajah of Sanggar, given to Lieutenant Owen Phillips, who had been sent to deliver rice for relief, and to collect information on the local effects of the eruption. ‘about seven PM on the 10^th of April, three distinct columns of flame burst forth near the top of Tomboro mountain.. and after ascending separately to a very great height, their caps united in the air. In a short time the whole mountain next Sangar appeared like a body of liquid fire extending itself in every direction’

In the main phase of the eruption, pyroclastic flows laid waste to much of the Sanggar peninsula, causing huge loss of life; and leaving a great collapse crater (caldera) where there had once been a tall volcanic peak.

Heinrich Zollinger was Swiss botanist, who moved to Java in 1841. In 1847, he led an expedition to Tambora and was the first scientist to climb to the crater rim since the eruption. In a short monograph, published in 1855, Zollinger describes his ascent of the volcano, documents the severe local impacts of the eruption, and details the numbers of people on Sumbawa affected by the eruption:

Location	Killed in the eruption	Died of hunger, or illness	Emigrated
Papekat	2000
Tambora	6000
Sangar	1100	825	275
Dompo	1000	4000	3000
Sumbawa		18000	18000
Bima		15000	15000
Total	10100	37825	36725

Zollinger also estimated that at least 10,000 also died of starvation and illness on the neighbouring island of Lombok; and current estimates for the scale of the calamity are that around 60,000 people died in the region.

The bicentennial of the eruption of Tambora is a sobering moment to reflect on the challenges that a future eruption of this scale would pose, whether it were to occur in Indonesia, or elsewhere. Our present-day capacity to measure volcanic unrest should certainly be sufficient for a future event of this scale to be detected before the start of an eruption; but would we be able to identify the potential scale of the eruption, or its impact, in advance? Much remains to be done to prepare for and mitigate against the local, regional and global consequences of a repeat of an explosive eruption of this scale – and we still have more to learn by taking a forensic  look back at past events.

References

Auker, MR et al., 2013, A statistical analysis of the global historical volcanic fatality records. Journal of Applied Volcanology 2: 2

Oppenheimer, C., 2003, Climatic, environmental and human consequences of the largest known historical eruption: Tambora volcano, Indonesia, 1815. Progress in Physical Geography 27, 230-259.

Raffles, S, 1816, Narrative of the Effects of the Eruption from the Tomboro Mountain, in the Island of Sumbawa on the 11th and 12th of April 1815, Verhandelingen van het Bataviaasch Genootschap van Kunsten en Wetenschappen [via Google Books]

Raffles, S, 1830. Account of the eruption from the Tomboro Mountain, pp 241-250; in Memoir of the life and public service of Sir Thomas Stamford Raffles, F.R.S. &c: particularly in the government of Java, 1811-1816, and of Bencoolen and its dependencies, 1817-1824, with details of the commerce and resources of the eastern archipelago, and selections from his correspondence. London, John Murray.

Self, S, et al., 1984, Volcanological study of the great Tambora eruption of 1815. Geology 12, 659-663.

Sigurdsson, H. and Carey SN, 1989, Plinian and co-ignimbrite tephra fall from the 1815 eruption of Tambora volcano. Bulletin of Volcanology 51, 243-270.

Stommel, H and Stommel, E, 1983, Volcano weather: the story of 1816, the year without a summer. Seven Seas Press, Newport, Rhode Island.

Stothers, R.B., 1984, The great Tambora eruption in 1815 and its aftermath. Science 224, 1191-1198.

Zollinger, H., Besteigung des Vulkanes Tambora auf der Insel Sumbawa, und schilderung der Erupzion desselben im Jahr 1815. [Ascent of Mount Tambora volcano on the island of Sumbawa, and detailing the eruption of the same in the year 1815]

Links to online resources, and further reading

Bill McGuire ‘Are we ready for the next volcanic catastrophe?’The Guardian, 28 March 2015.

Gillen Darcy Wood ‘1816, The Year without a Summer’ BRANCH: Britain, Representation and Nineteenth-Century History. Ed. Dino Franco Felluga. Extension of Romanticism and Victorianism on the Net.

Haraldur Sigurdsson ‘Tambora: the greatest explosion in history’, a National Geographic photo gallery.

Tambora bicentennial – collection of papers in Nature Geoscience (Paywalled)

Gillen D’Arcy Wood’s Tambora; and an entertaining book review by Simon Winchester, author of ‘Krakatoa, the Day the World Exploded’

Anja Schmidt, Kirsten Fristad, Linda Elkins-Tanton (eds), Volcanism and Global Environmental Change, Cambridge University Press, 2015.

Villarrica erupts. March 3, 2015, Chile.

Volcan Villarrica from the air in 2009.

 

Villarrica (Ruka Pillan in Mapudungun) is one of the most active volcanoes of southern Chile, and is a popular tourist destination in the heart of the Chilean Lake district. Villarrica has been in a continuous state of steady degassing for much of the past 30 years, since the last eruption in 1984-5, and began showing signs of increased unrest (seismicity, and visible activity in the summit crater) in February 2015. Eruptive activity at Villarrica in 1963-4 and 1971 was characterised by vigorous ‘Strombolian’ explosions from the summit – typically with short paroxysms of fire fountaining – followed by the formation of lava flows. The major hazards at Villarrica come from the lahars, which form as a result of the melting of snow and ice from the summit glacier by the intruding or erupting magma. In 1963 and 1971 the lahars that swept off the volcano caused considerable damage, and a number of fatalities in the affected areas.

At the present day, the volume of ice in the summit region is a little over 1 cubic kilometer. Any melt waters and lahars that may form as a consequence of the volcanic activity are expected to drain along any or several of the nine major lahar channels that were either active during the past eruptions of Villarrica, or have been identified from fieldwork and mapping. Recent work on the sediments from Lake Villarrica show that the transport of volcanic ash into the lake by lahars forms a very clear record of the small eruptions of the volcano that would otherwise not be preserved.

Map showing the nine major lahar channels (in blue) that drain off the summit of Villarrica, The area outlined in red shows the extent of the summit glacier field in Februiary 2011. The main tourist resort of Pucon, and lake Villarrica, lie to the north. In 1964, lahars caused  much damage to the village of Conaripe, to the south. Map from Rivera et al. (2015) , lahar channels from Castruccio et al. (2010).

The first Strombolian paroxysm from the 2015 eruption was reported shortly after 3 am local time on 3rd March; and this was followed by reports on social media of spontaneous evacuations from some of the communities that have been affected by lahars in the past. The Chilean agency responsible for civil protection (ONEMI, Oficina Nacional de Emergencia del Ministerio del Interior y Seguridad Pública) declared a ‘red alert‘ shortly afterwards, and SERNAGEOMIN also raised their technical ‘volcanic alert’ level to red. If the current phase of activity follows the pattern of past eruptions, there may be an extended period of elevated activity with intermittent paroxysms over the next few days to weeks.

This paroxysm just lasted a few tens of minutes, but released large puff of ash that rose to about 9 km above sea level and could be seen on geostationary weather satellites; a burp of sulphur dioxide that was visible from space, and coated the summit of Villarrica with a fresh coating of volcanic ‘spatter’.  On the volcano itself, there was clearly some melting of snow and ice, and small amounts of volcanic ash were washed down the local drainages, and into Lake Villarrica.

The footprint of the ‘hotspots’ associated with the freshly deposited ejecta can be seen in the alerts detected by University of Hawaii’s MODIS Thermal Alert System, using imagery from the MODIS sensors onboard NASA’s Terra and Aqua satellites.

Screen shot of the ‘thermal alerts’ detected by the HIGP MODIS Thermal Alert System for Villarrica, on 3 March 2015.

Update – March 5th, 2015.

The eruption was over quite quickly, and although a few thousand people evacuated at the time, most returned home later that day. Flights over Villarrica by the volcano monitoring and civil protection teams on March 3rd, and subsequent days, showed that the summit vent became sealed by fresh spatter during the eruption, but signs of activity diminished very quickly. SERNAGEOMIN reported that only one monitoring station was lost during the eruption, and their current scenario is that there may be some intermittent weak Strombolian activity in the near future, which should be readily detectable on the monitoring systems. Photographs posted on social media showed only little evidence for limited damage by lahars during this first eruption; including damage to a tourist centre on the volcano slopes.

Ongoing Activity

Latest status reports from ONEMI, Chile

Latest status reports from SERNAGEOMIN, Chile

Latest webcam images of Villarrica, from SERNAGEOMIN

Latest Volcanic Ash Advisories from the Buenos Aires VAAC

Further information

Great video footage of the 3rd March eruption from 24Horas

Collections of photos and video from BioBioChile,  24Horas, Cooperativa, the Guardian and SERNAGEOMIN.

Villarrica on Volcano Top Trumps

Villarrica pages at the Smithsonian Institution Global Volcanism Programme.

References

Castruccio, A. et al., 2010, Comparative study of lahars generated by the 1961 and 1971 eruptions of Calbuco and Villarrica volcanoes, Southern Andes of Chile, Journal of Volcanology and Geothermal Research 190, 297-311.

Rivera, A. et al., 2015, Recent changes in total ice volume on Volcan Villarrica, Southern Chile, Natural Hazards 75: 33 – 55

M van Daele, J Moernaut, G Silversmit, S Schmidt, K Fontijn, K Heirman, W Vandoome, M De Clercq, J van Acker, C Wolff, M Pino, R Urrutia, SJ Roberts, L Vincze, M de Batist, 2014, The 600 yr eruptive history of Villarrica volcano (Chile) revealed by annually laminated lake sediments, Geological Society of America, Bulletin doi:10.1130/B30798.1