Category Archives: Volcanoes

Studentships, Volcanoes

COMET Internship Blogpost – Methods to Measure Volcanic Plume Heights

Name of internship student: Geri Peykova, University of Oxford, Summer 2023

Why Measure Volcanic Ash Plume Heights?

Volcanic eruptions are natural phenomena that can have significant impacts on both local and global scales. One aspect of monitoring volcanic activity is measuring the height of the ash plumes they generate. Understanding the height of volcanic ash plumes is important for aviation safety, hazard management, and mitigating potential impacts on human health and the environment.

Aviation Safety

Volcanic ash poses a threat to aircraft engines, as it can cause engine failure by clogging fuel and cooling systems. Additionally, ash particles can scratch cockpit windows, obscure visibility, and interfere with aircraft navigation systems. By accurately measuring ash plume heights, aviation authorities can issue timely warnings and reroute flights to avoid hazardous areas, minimizing the risk to passengers and crew.

Hazard Management and Mitigation

Measuring volcanic ash plume heights is also crucial for hazard management and mitigation efforts. Ash plumes pose significant risks to human health, agriculture, infrastructure, and the environment. Understanding the height and dispersion of ash clouds allows authorities to assess the potential impact zones and implement appropriate measures to protect affected populations, such as evacuations, ashfall advisories, and distribution of respiratory protection equipment.

Satellite-Based Monitoring of Volcanic Eruptions

Satellites are an important tool for monitoring volcanic eruptions as they provide global coverage, allowing scientists to study volcanic activity anywhere on Earth, including remote and inaccessible regions. These spacecraft provide imagery of eruptions using various channels that capture different wavelengths of light ranging from visible to infrared and beyond. Each wavelength provides unique information about the eruption. For example, visible light imagery reveals the visual appearance of volcanic plumes and lava flows, while infrared imagery detects thermal emissions and provides temperature measurements. The data can also be utilized to find the heights of the eruptions.

Geometric Approach

Perhaps the most intuitive method for measuring volcanic ash plume heights is direct observation. The geometric approach involves imaging the plume from a satellite positioned to look sideways at the eruption and recording its angular size. We can then obtain an estimate of the height of the plume using trigonometry and the known distance to the volcano and zenith angle. The accuracy of this method is limited by the spatial resolution of the satellite instruments, which is typically around 500 meters for visual channels. Night time observations however rely on infrared channels, which have a coarser resolution of around 2 kilometers.

Brightness Temperature Method

The height of the eruption can also be inferred from data collected by a satellite positioned above the volcano, such as through the application of the brightness temperature method. For this technique, we use the fact that the top of the volcanic plume is in equilibrium with its surroundings and hence must match the ambient temperature. To get its altitude, the temperature of the ash cloud is measured from the infrared channels of the satellite and compared to the temperature profile of the atmosphere, derived from satellite data, weather stations and buoys. 

However, the structure of the atmosphere adds complexity to this measurement. In the troposphere, which extends from the Earth’s surface to the tropopause, temperature typically decreases with altitude. Conversely, in the stratosphere beyond the tropopause, temperature begins to increase with altitude. This temperature inversion creates multiple potential heights at which the plume’s temperature matches that of its surroundings. It’s important to distinguish between plumes reaching the stratosphere and those confined to the troposphere as gases and pollutants injected into the stratosphere remain there longer and can impact climate dynamics.

Introducing a New Method

In April 2021, the GOES-16 satellite observed the eruption of La Soufriere on the island of St. Vincent taking an overhead image every minute. The tenfold increase in temporal resolution allowed us to track the evolution of the ash plume in unprecedented detail and capture high-frequency and short-duration events that otherwise occur ‘in between takes’. One of the interesting features that we observed, the formation of waves within the plume, motivated the development of a novel method for measuring the heights of the eruption.

Plume Dynamics

The waves can be seen in the infrared images of the plume as light and dark blue fronts propagating radially outwards from the volcano. These temperature variations correspond to fluctuations in the altitude of air parcels within the ash cloud.

To understand the origin of these waves, imagine a rubber duck floating in a bathtub. When carefully placed in the water, the duck rests at what we term the “level of neutral buoyancy” (LNB) – the level at which its weight is perfectly balanced by the buoyant force. However, if the duck is dropped into the water from a height, it bounces up and down before eventually settling at the LNB. In the latter scenario, the duck’s inertia causes it to sink below LNB. As it sinks, it displaces water, creating an upward buoyant force. This pushes the duck back up and it overshoots the LNB slightly causing it to fall back down again. Similarly, rising air parcels within the ash plume exceed the LNB and experience buoyant forces due to the density difference between the surrounding atmosphere and the volcanic ash-laden air. When these air parcels surpass the level of neutral buoyancy, they oscillate around this equilibrium level, generating waves. 

Buoyancy Waves Method

The frequency at which these waves oscillate depends on the pressure and temperature of the surrounding air. Similarly to the brightness temperature method, we can use atmospheric data to reconstruct a frequency profile, which indicates the allowed frequency at different altitudes. Then to obtain the height, we just need to match it to the measured frequency of waves in the plume. This approach produces a single solution near the tropopause so we can uniquely determine the position of the plume. Moreover, the frequency varies strongly with altitude which significantly reduces the uncertainty of the measurement from hundreds to tens of meters. Finally, using infrared channels rather than visual means that we are not limited to daytime observations.

Conclusion

Observing volcanic eruptions and accurately measuring the height of ash plumes are vital for understanding and mitigating their impacts on society and the environment. Techniques such as the geometric approach, brightness temperature and buoyancy waves methods provide valuable insights into volcanic activity, while advancements in satellite technology continue to enhance our monitoring capabilities. By combining satellite data with innovative methods and scientific insights, we can improve our understanding of volcanic processes and better protect communities from volcanic hazards.

COMET news, Earthquakes, Volcanoes

COMET Celebrates International Women’s Day 2024

Today we celebrate all our amazing women at COMET and introduce you to some members of the COMET Directorate.

Meet COMET’s Co-Director Professor Juliet Biggs (Bristol), expert in using satellite techniques to study earthquakes and volcanoes.

Meet COMET’s Centre Manager, Charlie Royle (Leeds), expert in complex, cross-institutional programme delivery and strategic-planning.

Meet COMET’s Research and Events Officer Lucy Sharpson (Leeds), expert in the complexities of supporting multi-institute Centres and event planning.

Awards, Volcanoes

Professor David Pyle awarded Geological Society Murchison Medal

COMET Scientist Professor David Pyle (University of Oxford) is the recipient of the 2024 Murchison Medal, awarded by the Geological Society of London for his considerable contributions to the field of volcanology.

The Murchison Medal is awarded to geologists who have contributed significantly to ‘hard’ rock studies.  David is an internationally recognised volcanologist who has made outstanding contributions to understanding volcanic deposits and processes, using pioneering methods to characterise and classify tephra fall deposits and infer erupted volumes.

The Geological Society will host a formal awards ceremony on 12 June with more details of the day to be shared via its magazine Geoscientist, website and social media channels.

Congratulations David from all of your colleagues at COMET!

COMET news, Earth Observation, Volcanoes

Observations and models of Icelandic eruption lead to new understanding of volcanic systems

In November 2023, a state of emergency was suddenly declared in a fishing town in Iceland, Grindavík, and all residents were rapidly evacuated. In the space of around 6 hours, escalating seismic activity was felt: large cracks and fault movements occurred at the earth’s surface, and homes, businesses and infrastructure were destroyed.

This devastation was caused by huge amounts of magma moving at an unprecedented speed below the surface, which rushed into a crack that opened up below the town. The intrusion that formed was approximately 15-kilometres-long and extended around 1-5 km deep, with widening of up to 8 meters.

The processes and timescales behind the formation of major cracks, or “dikes”, aren’t currently fully understood but the international team of researchers behind a paper published in Science today have revealed new findings that shed some light on how these hazardous events occur.

Using detailed satellite observations alongside seismic measurements and physical modelling, the team of investigators led by University of Iceland and the Icelandic Meteorological Office, found that the magma flow rate under the surface of the earth reached an ultra-rapid and previously unrecorded speed of 7400 cubic meters per second. The study also shows that huge amounts of magma can be forced into cracks due to fracturing in the earth and tectonic stress, without much pressure coming from underlying magma source that feeds it. These findings demonstrate a significant hazard potential for this volcanic system and others with similar features, which can result in large-volume magmatic eruptions on the surface.

COMET Scientist, Professor Andy Hooper, was a key member of the team of investigators:

“Nothing like these rates of magma flow have ever been measured before. Luckily, the magma did not make it to the surface at that time, but this helps us understand how magma-filled cracks that are tens of kilometres long may have formed in the past.”

The events in November were the beginning of the activity in the affected area around Grindavík. Smaller magma intrusions occurred in December 2023 and January 2024, which unfortunately culminated in large eruptions and further devastation in the town, and a new, ongoing eruption started this morning (February 8th 2024).

Publication available here (open access for all for two weeks): https://www.science.org/doi/10.1126/science.adn2838

Awards, COMET news, Volcanoes

Edna Dualeh: 2024 Willy Aspinall Prize

 

VMSG has recently announced its 2024 award winners and we are delighted to announce that COMET staff researcher Edna Dualeh has been named as the recipient of the 2024 Willy Aspinall Prize for an outstanding paper on applied volcanology.

Edna’s work on St. Vincent was part of her PhD with COMET Scientist Susanna Ebmeier and COMET Director, Tim Wright both based at the University of Leeds.

You can read Edna’s winning paper here: doi.org/10.1016/j.epsl

Huge congratulations to Edna from all your colleagues at COMET!

Events, Volcanoes

Girls into Geoscience Careers Day

A group from the University of Bristol’s volcanology group represented COMET at the recent Girls into Geoscience careers day at the University of Plymouth. The group, consisting of MSc Volcanology students Alex Daniels, Anne-Marie Molina, Hannah Ellis, and PhD Student Ben Ireland, delivered a workshop showcasing a range of volcanological phenomena.

Anne-Marie and Alex had the following to say about the experience:

“We were at Plymouth University representing COMET for an event called “Girls into Geoscience”, where we talked about the different areas of volcanology to try and encourage these girls to pursue a career in geoscience! We wanted to pique their interest by showcasing volcanic rocks, drone imagery, and had a simulation of a volcanic eruption with a Coke and Mentos experiment. 

 We loved seeing the girls get involved with the interactive activities which they may not have access to in a classroom and loved their questions for us. It was really rewarding to see the girls understand volcanic processes through our experiment and get a sense of the intricacies which take place prior to a volcanic eruption in different settings around the world. This was an amazing opportunity to speak to so many girls with different backgrounds that came together with an interest in geoscience. It felt great to be able to inspire some of them with our own stories and hopefully they’ll pursue a career in geoscience!

 We hope to be back representing COMET at this great event next year!”

Earth Observation, Events, Volcanoes

‘Sensing Volcanoes’ at the Royal Society Summer Science Exhibition

From July 4 – 9 this year, a team from the University of Oxford, University of East Anglia and the University of the West Indies, Seismic Research Centre and Montserrat Volcano Observatory ran a multi-sensory installation as one of nine showcase exhibits at the Royal Society’s summer exhibition. Over six days, thirty volunteers helped to run the installation, manage the enthusiastic crowds of children and adults, and showcase aspects of volcanic and geophysical research.

The exhibit was designed around the ‘Curating Crises’ project [https://curatingcrises.omeka.net] funded by AHRC and NERC, which is exploring historical unrest at Caribbean volcanoes using data sources from archives – including the National Archives, the Royal Society, the British Geological Survey and the Montserrat Public Library.

The tag line for the exhibit was ‘sense, detect, imagine’. The idea was to explore how people living near a volcano might sense unrest; and how the detection of unrest feeds into the imagining, or interpretation, of what is happening underground, and what might happen next. To create sensory elements of the installation we had objects including an early 1900’s gramophone trumpet, with the sounds of bubbling geysers; an ash-covered cord telephone (from the 1990’s) with recorded eye-witness accounts of activity on Montserrat, and some tactile pots carved from scoria, impregnated with a mysterious ‘volcano scent’ that had been created for the exhibition. The highlight of the exhibit was the imaginarium – a ‘light up’ floor, controlled by a raspberry Pi. We ran this in two modes – one to represent the seismicity and movement of magma beneath La Soufrière, St Vincent during the 2021 eruption; and the second to run an interactive game on uncertainty and unrest, where the floor transformed into a map view of an island, which then turns out be a volcano.

The exhibit was busy for the whole of the exhibition, with over 4000 visitors to the building over the final weekend alone. Those who dropped by included Janice Panton, the Government of Montserrat representative; Turner-prize winning artist Veronica Ryan, and Cecil Browne, a Vincentian author. The exhibit is portable (with a van!) and will have another outing at the Oxford Festival of Science and Ideas in October.

Thank you to all of our volunteers, funders, and to the artists and creatives – Output Arts, Ωmega ingredients and Lizzie Ostrom – who helped to turn a 2-page vision statement into a physical exhibit in a little over six months!

https://curatingcrises.omeka.net/exhibits/show/sensing-royal-society/sensing-volcanoes

Written by Professor David Pyle, University of Oxford

Bridie Davies (UEA, now Manchester) checking the sound from the gramophone trumpet.
Stacey Edwards (UWI-SRC) and Jenni Barclay (UEA) checking the pendulum array and smelling stones.
The final stages of the uncertainty game. The volcano on the island has erupted, and places where people have chosen to live (represented by toys) have been affected by ash fallout (purple) or pyroclastic flows (orange).
COMET news, Earth Observation, Earthquakes, Tectonics, Volcanoes

Harmony: Mission Candidate for the Earth Explorer 10

Gallery

COMET scientists Professor Juliet Biggs (University of Bristol) and Professor Andy Hooper (University of Leeds) both serve on the Harmony Mission Advisory Group and are delighted to have been chosen to develop the concept further.

On February 18-19, ESA’s Programme Board for Earth Observation (PB-EO) decided on the continuation of the three Earth Explorer (EE) mission candidates towards the next phase in the path to their implementation. The three missions, namely, Daedalus, Hydroterra and Harmony, were selected in 2018 for a Phase-0 feasibility study out of 21 submitted proposals. The PB-EO has made now the unprecedented decision of selecting only one mission for Phase A, namely Harmony, instead of more than one as done in previous EE calls.

The Harmony mission is dedicated to the observation and quantification of small-scale motion and deformation fields at the air-sea interface (winds, waves, surface currents), of solid Earth (tectonic strain and height changes at volcanoes), and in the cryosphere (glacier flows and height changes). In order to achieve the different mission goals, the Harmony mission shall deploy two companion satellites following one of ESA’s Copernicus Sentinel-1 satellites. The companions will be flying in two different formations (see Figure 1): the stereo formation, with one Harmony satellite placed in front and one behind Sentinel-1, in both cases at a distance of about 350 km from it; and the cross-track formation, with both Harmony units flying close to each other (~200-500 m) also at 350 km from Sentinel-1. Each Harmony satellite carries as main payload a receive-only synthetic aperture radar (SAR), which shall acquire the reflected signals transmitted by Sentinel-1 towards the Earth. A multi-view thermal infra-red payload is also included to measure cloud height and cloud motion vectors. The angular diversity provided by the Harmonies in combination with Sentinel-1 will allow the retrieval of deformation measurements of the sea and earth surface with unprecedented accuracy (see Figure 2), while the cross-track configuration will allow the accurate measurement of elevation changes for land-ice and volcanic applications.

 

 

 

 

 

Figure 1: Representation of the (left) stereo and (right) cross-track flying formations for Harmony. The Sentinel-1 satellite is depicted in black color. Sentinel-1 transmits a signal and acquires the backscattered echoes (represented with magenta arrows), while the Harmony satellites receive part of the energy that bounces towards them (represented with the green arrows). Copyright: Harmony Mission Advisory Group.

Dr. Paco López-Dekker from the Delft University of Technology and principal investigator of the Harmony mission, comments “It is very exciting that our multi static-SAR concept, which combines many ideas that were matured during my years at HR, has made it to this final stage. During Phase-0 we have drafted a beautiful and elegant mission concept promising an unprecedented view at Earth System processes. Now we have the responsibility to look at it from all sides and be sure that it will work. Challenging and fun.”

Professor Juliet Biggs from the University of Bristol and member of Harmony’s Mission Advisory Group at ESA adds “The Harmony mission is remarkable in that it promises new scientific discoveries across an astonishing breadth of topics: from the gradual motion of tectonic plates to small-scale processes on the ocean surface. I’m delighted that we have been selected to develop the concept further and that Harmony is one step closer to becoming a reality”

Dr. Pau Prats, from the German Aerospace Centre, DLR and member of Harmony’s Mission Advisory Group at ESA, is convinced of the benefits a mission like Harmony will bring to the community: “The unique configuration of the Harmony satellites in combination with Sentinel-1 will allow us to literally add a new dimension to SAR observations, a fact that will foster SAR technology and its applications during the next two decades.”

Figure 2: Coloured areas show regions straining at greater than 10 nanostrain per year (the threshold above which 95% of earthquake fatalities occur). Blue regions are those that have a small component of north-south strain and can be imaged by Sentinel-1 alone. Red regions indicate the extra area that will be constrained by Harmony. From Harmony Report for Assessment. 2020.  

So, what’s next? Even though Harmony is currently the only EE-10 mission candidate it does not mean it will be implemented. The industry and science teams have one and a half years of hard work ahead to demonstrate the mission has reached the technological and scientific level of maturity required to enter into the next phase, that will ultimately result in the launch of the Harmony satellites by the end of this decade.

Announcement can be found on ESA website: https://www.esa.int/Applications/Observing_the_Earth/ESA_moves_forward_with_Harmony

Title figure for the Harmony mission. Copyright: ESA.

 

Volcanoes

New understanding of magma movements in volcano roots

An international group of research scientists including COMET researchers Prof. Tim Wright (COMET Director) and Prof. Andy Hooper, and led by Freysteinn Sigmundsson at the University of Iceland’s Institute of Earth Sciences, has presented a new method for evaluating when molten magma in volcano roots becomes unstable and forces its way towards the surface of the Earth. In an article published in the prestigious journal Nature Communications, the method is used to better understand precursors, onset and evolution of a large-volume eruption in Iceland in  2014-2015.

Just over five years have passed since the end of the 2014-2015 Holuhraun eruption in the Bardarbunga volcanic system; an eruption that produced the largest lava field in Iceland for more than 200 years. The data gathered in the time leading up to the eruption and during it has proven a valuable source for new discoveries in earth sciences in recent years, and now for improved understanding of magma movements in volcano roots.

In the study published in Nature Communications the group of scientists shed light on what conditions need to be in place in a volcano for an eruption to start, and furthermore how eruptions develop and lead to caldera formation, i.e. when a large part of a volcano subsides at the same time as a large amount of magma reaches the surface, as was the case in the 2014-2015 activity.

“Previous methods to understand magma movements in the surface have certain limitations and are based on assumptions that are not always applicable. It is also noteworthy that some large-volume eruptions have small or minor precursors in terms of increased earthquake activity and magma movements.  Small eruptions can on the other hand have large precursors.   This is not what is expected from commonly used models that volcanologists have used to interpret monitoring data from volcanoes,” Freysteinn points out.

The research consisted of developing a new method to take jointly into consideration three important effects that influence how magma accumulates and then forces its way to the surface.

Firstly, magma may be less dense than the host rock surrounding it. Where magma accumulates in volcano roots it can therefore have a large upward directed buoyancy force.  “This means that if sufficient magma accumulates, this force alone can break the surrounding host rock and magma can flow upwards,” explains Freysteinn.

Secondly, the host rock around magma bodies in volcano roots can behave as a ductile material. It can deform and flow in a ”viscoelastic manner” – such that solid rocks yields away from the magma and creates space for new magma without fracturing.  This can happen if magma accumulates over long time, many years or still longer time periods.

“Finally, it must be considered that magma can form pipe-like pathways e.g. by eroding away part of surrounding rocks where magma flows.  Such sustained magma channels do not easily close, even if pressure drops in underlying magma bodies that feed these magma channels.  This means that following the peak of an eruption such a channel can thus remain open for considerable time,” adds Freysteinn.

By connecting these three factors together into one methodology a new approach to understand magma movements was created. The method was then applied to the Iceland unrest and large-scale eruption in 2014-2015 to demonstrate its applicability. “The series of events can be explained by the existence of magma below Bárðabunga for a long time prior to the eruption.  The rock surrounding the magma yielded creating space for the magma.  Evaluation of the magma and rock’s density shows that the magma could easily flow upwards.  The magma was thus almost ready to burst forward, needing only a small inflow of additional magma to start the eruption. Thus a sustained magma channel was formed from the magma accumulation area resulting in a large drop in pressure leading to the caldera formation in Bárðarbunga,” explains Freysteinn.

The results are important as the method developed can be applied to all volcanoes.  “The method points to certain features that scientists and those who monitor volcanoes need to consider when estimating if a new eruption will begin. Large eruptions can occur with only minor precursory activity,” concludes Freysteinn.