From The Department of Earth Sciences
At
The University of Cambridge (UK)
6.13.24 [Just today from the institution]
Erin Martin-Jones
cmm201@cam.ac.uk
Eruption at Eyjafjallajökull April 17, 2010. Credit: Árni Friðriksson
Video footage of Iceland’s 2010 Eyjafjallajökull eruption is providing researchers from the University of Cambridge with rare, up-close observations of volcanic ash clouds — information that could help better forecast how far explosive eruptions disperse their hazardous ash particles.
Icelandic *ASH FALL* in May 2010; The Eyjafjallajökull Ash
When Eyjafjallajökull erupted in 2010, it ejected roughly 250 million tonnes of volcanic ash into the atmosphere: much of which was blown over Europe and into flight paths. With planes grounded, millions of air passengers were left stranded.
Forecasts of how ash will spread in the aftermath of an explosive eruption can help reduce impacts to aviation by informing decisions to shut down areas of airspace. But these forecasts require knowledge of what is happening at the volcano, information that often can’t be obtained directly and must instead be estimated.
In the new study, the researchers split a 17-minute film into time segments to understand how the Eyjafjallajökull ash cloud grew upwards and outwards as the eruption ensued.
“No one has previously observed the shape and speed of wind-blown ash clouds directly,” said Professor Andy Woods, lead author of the study from Cambridge’s Department of Earth Sciences and Institute for Energy and Environmental Flows. Their new video analysis method was reported in Nature Communications Earth and Environment.
Fig. 1: Video-based measurement of the speed of the wind and of the ash plume.
a Photograph of the ash plume captured during the eruption. b Time series of the horizontal row of pixels marked by the dotted line in (a). On the left hand side of this time series image, we observe the trajectories in time of the white vapour clouds (see black arrow), which are visible against the blue sky background in (a). On the right hand side of the time series image, we observe the trajectories in time of the eddies in the plume (see white arrows). c Vertical profiles of the horizontal speed of the clouds/wind (red diamonds) and of the eddies in the plume, in the region x > 3000 m (black dots). d The vertically-averaged mean speed of the clouds/wind is approximately constant during the 17 min recorded. The error bars illustrate the standard deviation of the velocity measurements relative to the mean. e The black solid line illustrates the time-averaged horizontal speed of eddies in the plume, plotted as a function of downwind distance from the source, as measured at a height z ≈ 850 m above the vent. At large distances from the vent, x > 2500 m, this speed approximates the background speed of the clouds at the same height z ≈ 850 m (red dotted line), which we assume to be close to the wind speed.
Fig. 2: Measurement of the height and radius of the volcanic plume as a function of time and distance from the vent.
Time series of three columns of pixels, located at different downwind distances in the plume: (a) x ≈ 975 m, (b) x ≈ 1625 m and (c) x ≈ 2275 m. d The time series image in (c) is thresholded in order to identify the edges of the ash cloud (red lines). The instantaneous centre of the cloud, zc(x, t), is defined as the locus of points which are equidistant from the edges (white dotted line), while the instantaneous radius of the cloud, r(x, t), is the distance between the cloud centre and either edge.
See the science paper for further instructive material with images.
By comparing characteristics of the ash cloud, such as its shape and speed, at time intervals through the video, the researchers were able to calculate the amount of ash spewed from the volcano.
That rate of ash flow, called eruption rate, is an important metric for forecasting ash cloud extent, said Woods. “The eruption rate determines how much ash goes up into the atmosphere, how high the ash cloud will go, how long the plume will stay buoyant, how quickly the ash will start falling to the ground and the area over which ash will land.”
Generally, the higher the ash plume, the wider the ash will be dispersed, and the smaller the ash particles are, the longer they stay buoyant. This dispersal can also depend on weather conditions, particularly the wind direction.
Volcanoes across the world are increasingly monitored via video, using webcams or high-resolution cameras. Woods thinks that, if high frame rate video observations can be accessed during an eruption, then this real-time information could be fed into ash cloud forecasts that more realistically reflect changing eruption conditions.
During the 17-minute footage of the Eyjafjallajökull eruption, the researchers observed that the eruption rate dropped by about half. “It’s amazing that you can learn eruption rate from a video, that’s something that we’ve previously only been able to calculate after an eruption has happened,” said Woods. “It’s important to know the changing eruption rate because that could impact the ash cloud dispersal downwind.”
It’s usually challenging for volcanologists to take continuous measurements of ash clouds whilst an eruption is happening. “Instead, much of our understanding of how ash clouds spread in the atmosphere is based on scaled-down lab models,” said Dr Nicola Mingotti, a researcher in Woods’ group and co-author of this study. These experiments are performed in water tanks, by releasing particle-laden or dyed saline solutions and analysing footage of the plume as it dissipates.
Woods and his collaborators have been running lab experiments like these for several years, most recently trying to understand how eruption plumes are dragged along by the wind. But it’s a big bonus to have video measurements from a real eruption, said Woods, and the real observations agree closely with what they’ve been observing in the lab. “Demonstrating our lab experiments are realistic is really important, both for making sure we understand how ash plumes work and that we forecast their movements effectively.”
See the full article here .
Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct.
five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.
The Department of Earth Sciences offers world-leading education and carries out innovative and ground-breaking research, using excellent facilities in a dynamic, welcoming and inclusive environment.
The department’s history can be traced back to 1731 when the 1st Woodwardian Professor of Geology was appointed, in accordance with the bequest of John Woodward. The present Department of Earth Sciences was formed by an amalgamation of the Department of Geology, Department of Geodesy and Geophysics and the Department of Mineralogy and Petrology in 1980.
The main location of the department is at the Downing Site, Downing St. The Bullard Laboratories, located in West Cambridge on Madingley Rd is a satellite department of the main building. The department incorporates the Sedgwick Museum of Earth Sciences and the Godwin Laboratory.
The University of Cambridge (UK) [legally The Chancellor, Masters, and Scholars of the University of Cambridge] is a collegiate public research university in Cambridge, England. Founded in 1209 Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford (UK) after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.
Cambridge is formed from a variety of institutions which include 31 semi-autonomous constituent colleges and over 150 academic departments, faculties and other institutions organized into six schools. All the colleges are self-governing institutions within the university, each controlling its own membership and with its own internal structure and activities. All students are members of a college. Cambridge does not have a main campus and its colleges and central facilities are scattered throughout the city. Undergraduate teaching at Cambridge is organized around weekly small-group supervisions in the colleges – a feature unique to the Oxbridge system. These are complemented by classes, lectures, seminars, laboratory work and occasionally further supervisions provided by the central university faculties and departments. Postgraduate teaching is provided predominantly centrally.
Cambridge University Press a department of the university is the oldest university press in the world and currently the second largest university press in the world. Cambridge Assessment also a department of the university is one of the world’s leading examining bodies and provides assessment to over eight million learners globally every year. The university also operates eight cultural and scientific museums, including the Fitzwilliam Museum, as well as a botanic garden. Cambridge’s libraries – of which there are 116 – hold a total of around 16 million books, around nine million of which are in Cambridge University Library, a legal deposit library. The university is home to – but independent of – the Cambridge Union – the world’s oldest debating society. The university is closely linked to the development of the high-tech business cluster known as “Silicon Fe”. It is the central member of Cambridge University Health Partners, an academic health science centre based around the Cambridge Biomedical Campus.
By both endowment size and consolidated assets Cambridge is the wealthiest university in the United Kingdom. The central university – excluding colleges – has a total income of over £2.5 billion of which over £600 million is from research grants and contracts. The central university and colleges together possess a combined endowment of over £7 billion and overall consolidated net assets (excluding “immaterial” historical assets) of over £12.5 billion. It is a member of numerous associations and forms part of the ‘golden triangle’ of English universities.
Cambridge has educated many notable alumni including eminent mathematicians, scientists, politicians, lawyers, philosophers, writers, actors, monarchs and heads of state. Nobel laureates, Fields Medalists, Turing Award winners and British prime ministers have been affiliated with Cambridge as students, alumni, faculty or research staff. University alumni have won many Olympic medals.
History
By the late 12th century, the Cambridge area already had a scholarly and ecclesiastical reputation due to monks from the nearby bishopric church of Ely. However, it was an incident at Oxford which is most likely to have led to the establishment of the university: three Oxford scholars were hanged by the town authorities for the death of a woman without consulting the ecclesiastical authorities who would normally take precedence (and pardon the scholars) in such a case; but were at that time in conflict with King John. Fearing more violence from the townsfolk scholars from the University of Oxford started to move away to cities such as Paris, Reading and Cambridge. Subsequently enough scholars remained in Cambridge to form the nucleus of a new university when it had become safe enough for academia to resume at Oxford. In order to claim precedence, it is common for Cambridge to trace its founding to the 1231 charter from Henry III granting it the right to discipline its own members (ius non-trahi extra) and an exemption from some taxes; Oxford was not granted similar rights until 1248.
A bull in 1233 from Pope Gregory IX gave graduates from Cambridge the right to teach “everywhere in Christendom”. After Cambridge was described as a studium generale in a letter from Pope Nicholas IV in 1290 and confirmed as such in a bull by Pope John XXII in 1318 it became common for researchers from other European medieval universities to visit Cambridge to study or to give lecture courses.
Foundation of the colleges
The colleges at the University of Cambridge were originally an incidental feature of the system. No college is as old as the university itself. The colleges were endowed fellowships of scholars. There were also institutions without endowments called hostels. The hostels were gradually absorbed by the colleges over the centuries; but they have left some traces, such as the name of Garret Hostel Lane.
Hugh Balsham, Bishop of Ely, founded Peterhouse – Cambridge’s first college in 1284. Many colleges were founded during the 14th and 15th centuries but colleges continued to be established until modern times. There was a gap of 204 years between the founding of Sidney Sussex in 1596 and that of Downing in 1800. The most recently established college is Robinson built in the late 1970s. However, Homerton College only achieved full university college status in March 2010 making it the newest full college (it was previously an “Approved Society” affiliated with the university).
In medieval times many colleges were founded so that their members would pray for the souls of the founders and were often associated with chapels or abbeys. The colleges’ focus changed in 1536 with the Dissolution of the Monasteries. Henry VIII ordered the university to disband its Faculty of Canon Law and to stop teaching “scholastic philosophy”. In response, colleges changed their curricula away from canon law and towards the classics; the Bible; and mathematics.
Nearly a century later the university was at the centre of a Protestant schism. Many nobles, intellectuals and even commoners saw the ways of the Church of England as too similar to the Catholic Church and felt that it was used by the Crown to usurp the rightful powers of the counties. East Anglia was the centre of what became the Puritan movement. In Cambridge the movement was particularly strong at Emmanuel; St Catharine’s Hall; Sidney Sussex; and Christ’s College. They produced many “non-conformist” graduates who, greatly influenced by social position or preaching left for New England and especially the Massachusetts Bay Colony during the Great Migration decade of the 1630s. Oliver Cromwell, Parliamentary commander during the English Civil War and head of the English Commonwealth (1649–1660), attended Sidney Sussex.
Modern period
After the Cambridge University Act formalized the organizational structure of the university the study of many new subjects was introduced e.g. theology, history and modern languages. Resources necessary for new courses in the arts architecture and archaeology were donated by Viscount Fitzwilliam of Trinity College who also founded the Fitzwilliam Museum. In 1847 Prince Albert was elected Chancellor of the University of Cambridge after a close contest with the Earl of Powis. Albert used his position as Chancellor to campaign successfully for reformed and more modern university curricula, expanding the subjects taught beyond the traditional mathematics and classics to include modern history and the natural sciences. Between 1896 and 1902 Downing College sold part of its land to build the Downing Site with new scientific laboratories for anatomy, genetics, and Earth sciences. During the same period the New Museums Site was erected including the Cavendish Laboratory which has since moved to the West Cambridge Site and other departments for chemistry and medicine.
The University of Cambridge began to award PhD degrees in the first third of the 20th century. The first Cambridge PhD in mathematics was awarded in 1924.
In the First World War 13,878 members of the university served and 2,470 were killed. Teaching and the fees it earned came almost to a stop and severe financial difficulties followed. As a consequence, the university first received systematic state support in 1919 and a Royal Commission appointed in 1920 recommended that the university (but not the colleges) should receive an annual grant.
Following the Second World War the university saw a rapid expansion of student numbers and available places; this was partly due to the success and popularity gained by many Cambridge scientists.