Past seminars


Return to the list of forthcoming seminars.

# Monday 18th May 2026, 1.00pm – Dr. Chris Satow, Royal Holloway University of London
Climatic Controls on Volcanic Systems? Theories, evidence and future opportunities
Venue: Harker 1, Department of Earth Sciences

Climatic Controls on Volcanic Systems? Theories, evidence and future opportunities

Abstract: Since the 1980s possible mechanisms attributing changes in volcanic activity to changes in the climate have been discussed in the volcanological community. These proposed mechanisms have covered a large range of temporal and spatial scales e.g. from the influence of global, glacial-interglacial sea level changes on volcanic CO2 fluxes, to the local triggering of individual eruptions by extreme rainfall events. Some mechanisms have evidence bases to support them, while others remain speculative. Investigating these mechanisms requires considerable interdisciplinary understanding and methods; combining field sampling and laboratory work with advanced geophysical and atmospheric modelling. This talk will summarise the state of the question and identify potentially fruitful future avenues of research for the volcanological community.

# Monday 11th May 2026, 1.00pm – Frankie Haywood, University of Bristol
Pantellerite eruptions are extremely susceptible to sintering and cryptic fragmentation
Venue: Tilley Lecture Theatre, Department of Earth Sciences, Downing Street

Pantellerite eruption deposits display histories of repeated explosive-effusive eruption transitions with no apparent change in magma characteristics. Across the varied eruption styles, the peralkaline rhyolite deposits have high pre-eruptive water contents and low crystal contents; as such, the control behind these transitions remains unexplained. In this work, we present new field, textural and experimental data from Tūhua (New Zealand) to propose that all pantellerite eruptions are fed by explosive volcanism. Subsequently, dense, lava-like pantellerite deposits are produced through thorough post-depositional sintering or syn-eruption cryptic fragmentation of these lower-viscosity rhyolites. We also provide evidence that oxidation could influence the behaviour of these iron-rich melts, and explore how this could affect eruption behaviours.

# Monday 23rd February 2026, 1.00pm – Dr. Joshua Shea, University of Cambridge
Constraining Carbon in Earth’s Mantle
Venue: Harker 1, Dept of Earth Sciences

In situ carbon isotopes are a powerful but under-utilised tracer of mantle processes, in part due to analytical challenges and lack of reference materials. In this talk, I present a new SIMS method for concurrently measuring carbon isotopes and carbon concentration in basaltic glass, enabling improved precision at low carbon concentrations and high spatial resolution. Applying this method to olivine-hosted melt inclusions, I first describe recent work constraining the convecting upper mantle, which yields a more positive and more tightly defined δ13C value than previously assumed, along with a lower organic burial fraction of carbon. I then present results from the Icelandic primordial mantle reservoir sampled at Miðfell, revealing anomalously heavy carbon isotopic compositions coupled with depleted incompatible element concentrations, potentially linking early core formation to modern mantle heterogeneity. Together, these results refine the mantle carbon baseline and deep carbon cycle and demonstrate how melt inclusions retain isotopic memory of Earth’s interior processes.

# Monday 9th February 2026, 1.00pm – Prof. Thomas Aubry, University of Oxford
Modelling explosive volcanic eruptions from proximal hazards to global climate disruption
Venue: Harker 1, Dept of Earth Sciences

Explosive volcanic eruptions have critical impacts on our environment and societies including local-regional scale devastation from pyroclastic flows and tephra fallout, regional-continental scale air pollution and airspace shutdown, and global-scale cooling of Earth’s surface. I will give an overview of my group research and how it contributes to understanding and managing these impacts. First, I will discuss how volcanic plume modelling, informed by laboratory experiments and observational databases, helps us understand the relationship between eruption intensity, atmospheric conditions and the height of injection of volcanic ash and gas into the atmosphere. Second, I will discuss how numerical models ranging from reduced-complexity models to full-blown Earth System Models with interactive stratospheric aerosols can help us constrain the radiative forcing and climatic impacts of volcanic eruptions. Using ice-core, geological and satellite records, I will apply these models to discuss volcanic impacts on climate from 8,000 BC to 2100. Last, I will bring together volcanic plume, aerosol and climate modelling to interrogate how ongoing climate change driven by anthropogenic activities will affect the life cycle of volcanic stratospheric aerosols, and whether we should expect more or less volcanic cooling as Earth warms.

# Wednesday 28th May 2025, 1.00pm – Dr Benjamin Devenish (Met Office)
Modelling the dispersion of volcanic ash in the atmosphere
Venue: Small Lecture Theatre (SLT), Department of Geography

Abstract not available

# Monday 12th May 2025, 1.00pm – Professor Claire Horwell (Durham University)
The curious incident of the cristobalite in the Mount St Helens dome
Venue: Small Lecture Theatre (SLT), Department of Geography

Abstract not available

# Monday 3rd March 2025, 1.00pm – Professor Matthew Watson (University of Bristol)
Volcanoes, Rhinoceros and Cabbage
Venue: Tilley Lecture Theatre, Department of Earth Sciences, Downing Street

Abstract not available

# Monday 11th November 2024, 1.00pm – Zoltán Taracsák (University of Cambridge)
Tracking the behaviour of sulfur in oxidised magmas using sulfur isotopes
Venue: Harker 1, Department of Earth Sciences, Downing Street

Sulfur emissions from volcanoes influence Earth’s climate, have profound effects on the local environment and human health during volcanic eruptions, and provide a tool to monitor volcanic activity from space. How much sulfur is released during volcanic eruptions is a complex interplay of magma storage pressure, temperature, melt sulfur content, and melt redox state. Sulfur isotope fractionation during sulfur degassing and sulfide saturation provides information on the fate of sulfur in magmatic systems. Sulfur isotopes ratios measured in melt inclusions and glasses in oxidised magmas from ocean islands and arc magmas can help to constrain sulfur speciation in the gas and melt during melt evolution, and how changes in redox can influence where sulfur ends up in magmatic systems.

# Monday 28th October 2024, 1.00pm – Carrie Soderman (University of Cambridge)
The formation of co-genetic silica-undersaturated and silica-oversaturated igneous rocks: pressure, fractional crystallisation and crustal assimilation
Venue: Harker 1, Department of Earth Sciences, Downing Street

Alkaline-silicate igneous complexes can host significant resources of critical metals and contain a diversity of co-genetic rock types from silica-oversaturated (quartz normative) to silica-undersaturated (feldspathoid normative) compositions. The origin of these coexisting rocks is an ongoing petrological problem, due to the separation of the two regimes by thermal divides. Here we apply new thermodynamic models to investigate the co-genetic formation of these rock types using two case studies: 1) the Blatchford Lake Igneous Complex (Canada), which also hosts a world-class REE deposit associated with the silica-undersaturated units; and 2) the ‘giant dyke’ complexes in south Greenland, which our group visited this summer. We quantify the effects of fractionation, crystallisation pressure and crustal assimilation to identify key conditions under which evolved alkaline melts, which are optimal for critical metal mineralisation, may be generated.

# Monday 14th October 2024, 1.00pm – Max Van Wyk De Vries (University of Cambridge)
Exploring changes in exposure to glaciovolcanic hazard
Venue: Harker 1, Department of Earth Sciences, Downing Street

Abstract not available

# Monday 13th May 2024, 1.00pm – Lara Mani (University of Cambridge)
Building global resilience to volcanic eruptions
Venue: Harker 1, Department of Earth Sciences, Downing Street

Abstract not available

# Wednesday 8th May 2024, 5.00pm – Blaise Mafuko Myandwi (University of Goma, DRC) and Amy Donovan (University of Cambridge)
How can social sciences be used to explore how communities think and feel about volcanic risk and to better inform disaster risk management?
Venue: Large Lecture Theatre, Department of Geography, Downing Site

Abstract not available

# Thursday 24th November 2022, 1.00pm – Dr Katrin Kleemann, German Maritime Museum – Leibniz Institute for Maritime History
A Peculiar Haze, a Sulphuric Smell, and Bloodred Sunsets: The Effects of the 1783-1784 Laki Eruption on Europe
Venue: Department of Geography, Small Lecture Theatre

In mid-June 1783, a peculiar haze descended upon Europe. It quickly became apparent that this was no ordinary fog: It was dry rather than wet, lasted for months, and turned the sun and moon bloodred. Day by day, the haze grew increasingly dense. By the last week of June, the concentrations of its pollutant properties seemingly reached their peak: Contemporaries in parts of England, the Low Countries, and the German Territories reportedly tasted sulphur in the fog with every drawn breath. There were complaints of sore eyes and throats, breathing difficulties, and asthmatic attacks. Then, seemingly overnight, an apparent frost swept through towns, villages, and farms, destroying the vegetation in its path.

These events inspired many to speculate about their cause. Unbeknown to mainland Europeans at the time, a 27-kilometer-long fissure volcano had sprung to life in the remote Icelandic highlands. The Laki fissure produced the largest lava volume of any volcanic eruption in the last millennium. In Iceland, volcanic ejecta poisoned the fields, meadows, and ponds, which caused malnutrition, hunger, and disease in the human population. The jet stream then carried the ejecta to Europe, where it was a catalyst for many a fierce debate. In the spirit of the Enlightenment, naturalists used reason and experimentation in an attempt to lift the fog of ignorance.

News about this volcanic eruption only reached Europe after the fog had vanished. As a result, the real origin of this corrosive fog remained a mystery for over a century.

# Thursday 17th June 2021, 1.00pm – Kim Huppert – GFZ Postdam
Storms, surf, & swells: Bedrock breakdown and the geodynamic demise of volcanic ocean islands
Venue: Zoom webinar – link to follow

With homogeneous bedrock, dramatic climate gradients, and remnant surfaces that constrain their age, initial topography, and vertical motions relative to sea level, volcanic ocean islands provide an exceptional natural experiment in landscape evolution. Analyses traversing gradients in island climate and bedrock age have the potential to advance our understanding of climatic and tectonic influences on landscape evolution in a diverse range of continental settings. Yet, as net subsiding and boundary-dominated landmasses, islands are in some ways dissimilar to most continental landscapes, and the mechanisms of island vertical motion remain largely enigmatic. Island uplift and subsidence can provide important observational constraints on the rheology and dynamics of the Earth’s interior, in addition to setting the boundary conditions for the topographic, climatic, and biogeographic evolution of island landscapes. In this talk, I exploit steep climate gradients in the Hawaiian Islands to quantify controls on fluvial and coastal erosion, and I assess the contribution of lithosphere and mantle processes to surface deformation at ocean hotspots. Through physically-based modeling, analysis of topo-bathymetric and geochronologic data, and field measurements, I examine (1) the control of rainfall variability on long-term rates of bedrock river incision on the Hawaiian Island of Kaua’i, (2) the influence of wave power on bedrock coastal erosion in the Hawaiian Islands, and (3) the mechanisms that cause volcanic ocean islands to drown below sea level to form atolls and guyots. These analyses provide empirical support for hypothesized feedbacks between climate, tectonics, and topography, linking the evolution of the solid earth, hydrosphere, and biosphere.

# Thursday 27th May 2021, 1.00pm – Simon Matthews – University of Iceland
Crystallisation temperatures as a proxy for mantle temperature; and the 2021 eruption in Reykjanes
Venue: Zoom webinar – link to follow

Abstract not available

# Thursday 18th March 2021, 1.00pm – Aleeza Wilkins and Alice Pennaz (USGS)
2018 Eruption of Hawaii’s Kilauea Volcano – Use of Social Media and the U.S. Department of Interior Strategic Sciences Group
Venue: Zoom webinar – link to follow

The 2018 Kilauea eruption, which began on May 3 and lasted 107 days, was one of the longest eruptions in recent history in the lower Puna district of Hawaii. Over 700 homes were destroyed, and there was additional damage to the USGS Hawaiian Volcanoes Observatory as well as to critical infrastructure within the Hawaii Volcanoes National Park. Many federal, state, and local agencies and organizations supported response to this historic event. In this seminar, the speakers will describe how the USGS used social media to deliver nearly 24/7 volcano hazards information and build trust during the crisis. The speakers will then describe how the unique approach of DOI’s Strategic Sciences Group (SSG) provided insights to help identify potential social, environmental, and economic consequences of the eruption.

# Thursday 4th March 2021, 1.00pm – Dr Audrey Michaud-Dubuy, Institut de Physique du Globe de Paris
Refined eruptive history of Mount Pelée volcano and implications for tephra fallout hazard in Martinique
Venue: Zoom webinar – link to follow

Mount Pelée volcano (Martinique) is one of the most active volcanoes in the Lesser Antilles arc with at least fifteen magmatic events in the last 5,000 years, including the deadliest eruption of the twentieth century in 1902. Our knowledge of the eruptions older than 5 ka is however very limited, thus reducing our capacity to predict the dynamics of future eruptions at Mount Pelée.

Two new extensive field studies performed in 2017 and 2019 in Martinique combined with carbon-dating measurements allow us identifying six new eruptions in the past 24 ka cal BP, including four Plinian and two Pelean eruptions. We reconstruct the dynamical evolution of the newly discovered Plinian eruptions of Bellefontaine (13.5 ka cal BP), Carbet (14 ka cal BP) and Etoile (21.5 ka cal BP) whose great interest stems from their unusual southward dispersal axis encompassing areas that are considered to be safe in current hazard maps. Using the 2-D ash dispersion HAZMAP model, we identify peculiar atmospheric circulations associated to a modification of the subtropical jet-stream path producing northerly winds over Martinique and thus spreading ash towards the most populated areas of the island.

This integrated approach, combining field studies and model predictions, allows us to build new volcanic hazard maps for tephra fallout in Martinique. Our method is based on 16 eruptive scenarios, consistent with the data retrieved from our stratigraphical records. Each scenario considers a different pair of deposit mass and mass discharge rate, and is given a probability of occurrence calculated from the complete eruptive history of the volcano. We use the ERA-5 database to consider the daily variability of winds. These new probability maps, as well as the predicted range of damages that could be expected at key infrastructures in Martinique, will be useful to revisit the emergency procedures as the volcanological observatory (OVSM) recently raised Mount Pelée volcano on alert level 2.

# Thursday 18th February 2021, 1.00pm – Dr Esti Handini, Universitas Gadjah Mada
Looking Through the Sunda Arc: An Overview of Java’s Magmatism
Venue: Zoom webinar – link to follow

The Sunda arc is a simple-looking island arc at the western tip of Pacific Ring of Fire, extending from the Andaman islands in the North and Sumatra in the West to the small volcanic islands in the north of Savu Sea in the East. The current active arc is built on top of composite crustal blocks, and has been active since Miocene. This more recent style of activity occurred after the Cretaceous subduction period ceased, and arc activity shifted towards the north. Today, the Sunda Arc is one of the most active volcanic arcs in the world, with 95 Quaternary volcanic centers.
The groundwork on Sunda arc magma geochemistry was laid in the 1970s (as early as 1973), and has now reached a new peak of data accumulation and complexity. This allows us to look through a large-scale systematics of arc geochemistry. Understanding this geochemical framework should provide an opportunity to understand the interplay between the three main subduction zone components (i.e., mantle source, subducting slab, and the overriding crust) and their role in the generation of magmas along Sunda arc.
This talk will provide (1) an introduction to the general geochemical systematics along Sunda arc, followed by (2) a closer look into the across-arc chemical systematics in Central Java. In the first part I will briefly show you the geochemical variation of volcanics from along the arc to show the variable association with the underlying crustal blocks. In the second part I will highlight my recent work, which seeks to untangle the subduction contribution across Merapi-Muria volcanic line in Central Java, where the slab-mantle wedge interface goes deeper than the rest of the arc segments, using trace elements and radiogenic isotopes

# Thursday 19th November 2020, 1.00pm – Jacob Richardson, NASA/GSFC
Exploring volcanoes in Central Iceland as Analogs for Planetary Environments
Venue: Zoom webinar – link to follow

Abstract not available

# Thursday 5th November 2020, 1.00pm – Alia Juman, University of the West Indies, St. Augustine
A Caribbean Vacay: Sun, Sand, Sea and Volcanoes?! An introduction into volcanic outreach in the Eastern Caribbean
Venue: Zoom webinar – link to follow

Abstract not available

# Thursday 22nd October 2020, 1.00pm – Joshua Jones (Virginia Tech)
Modeling volcano-tectonic interactions in a youthful continental rift: the East African Rift System
Venue: Zoom webinar – link to follow

Abstract not available

# Thursday 8th October 2020, 1.00pm – Dr Julie Morin, Department of Geography
Integrating social and institutional vulnerabilities into volcanic risk scenarios: A case study at Nevado Cayambe, Ecuador
Venue: Zoom webinar – link to follow

Eight hundred million people live near active volcanoes worldwide, however many of them have never experienced volcanic eruptions or their associated hazards. While the volcanologist community provides essential understanding about volcanic systems, geographers and other social scientists share an equally fundamental role in assessing dimensions of vulnerability and risk and aiding preparedness efforts and managing volcanic crises.

Our current case study focuses on Cayambe Volcano in Northern Ecuador, which began to show signs of unrest in 2016. It is covered with a 22 km2 glacier that could trigger deadly mudflows in the city of Cayambe in a future eruption. However, little was done to prepare the population. As geographers facing the evidence of this preparedness “void”, we desire to build a pilot rapid assessment framework, based on data collected at Cayambe, which can be used to minimize the impact of hazard events. The framework includes for instance vulnerability assessments, risk perception, and evacuation modelling. It beneficiates from the inputs of colleagues from other disciplines working in volcanic environments, and from the close collaboration of the local communities and Civil Protection authorities. We aim to provide a set of preliminary guidelines for building a “social sciences framework” and conducting a rapid assessment to better address complex cases of volcanic unrest at other understudied, potentially active volcanoes.

# Thursday 18th June 2020, 1.00pm – Emma Horn, University of Southampton
Snapshot of a magmatic system immediately prior to an explosive eruption: Tenerife 289 ka
Venue: Webinar (via Zoom online)- link to follow

Abstract not available

# Thursday 11th June 2020, 1.00pm – Callum Reekie, Earth Sciences Department, University of Cambridge
Exploring controls on the distribution of sulfur-loving elements in Icelandic magmas
Venue: Webinar (via Zoom online)- link to follow

Chalcophile (sulfur-loving) and siderophile (iron-loving) elements (e.g., Cu, Ag, Pt and Au; collectively called CSE) are of significant economic importance. In basaltic melts, the abundance and distribution of CSE is chiefly controlled by sulfide minerals, both during partial melting and crustal differentiation processes. Typically, melts depleted in CSE are considered to have become sulfide-saturated during crustal differentiation. However, recent work has shown that CSE abundances and ratios correlate with lithophile element proxies which are sensitive to mantle fertilisation and melting processes. In this talk I will discuss our results from Icelandic basalts. Importantly, Icelandic basalts have been shown to be derived from a chemically and lithologically heterogeneous mantle source, and could therefore be key to unravelling the different controls on CSE variability in basaltic melts.

# Thursday 4th June 2020, 1.00pm – Dr Emma Liu, University College London
Volcanic activity along the enigmatic South Sandwich arc
Venue: Webinar (via Zoom online)- link to follow

Abstract not available

# Thursday 28th May 2020, 1.00pm – Lis Gallant (University of Cambridge)
Assessing hazards in distributed volcanic fields
Venue: Webinar (via Zoom online)- link to follow

Abstract not available

# Thursday 21st May 2020, 9.00am – Rachael Baxter, Earth Sciences Department, University of Cambridge
Initiation of a composite volcano: The complex beginnings of the long-lived Dunedin Volcano, New Zealand
Venue: Webinar (via Zoom online)- link to follow

Abstract not available

# Thursday 14th May 2020, 1.00pm – Dr Elena Maters (University of Cambridge, Department of Chemistry)
Experimental insights on volcanic ash as a reactive agent in the environment
Venue: Webinar (via Zoom online)- link to follow

Abstract not available

# Wednesday 19th February 2020, 1.00pm – Lauren Davies, University of Alberta
Implications of Holocene cryptotephra records in North America
Venue: Department of Earth Sciences – Harker II

Records of far-travelled volcanic ash, not visible to the naked eye but detectable in sediment records, have expanded in North America over the past 12 years. Analyses of ash transported from volcanic source regions over 1000s of km away, including Kamchatka, Alaska and central America, provide detailed data across the Holocene that can be utilised for many purposes. This seminar will touch on what records have been produced, some practical lessons learnt about undertaking this work in North America, and implications of the new datasets for other research topics, including eruptive histories, atmospheric circulation and independently assessing modern chronostratigraphies.

# Monday 2nd December 2019, 12.30pm – Marie Edmonds
Daly Lecture Preview
Venue: Department of Earth Sciences – Harker II

Abstract not available

# Monday 2nd December 2019, 12.00pm – Cambridge University
Tracking sulfur and its chalcophile allies at Kilauea Volcano, Hawaii: A story of sulfide saturation, sulfide resorption and magmatic degassing
Venue: Department of Earth Sciences – Harker II

Abstract not available

# Wednesday 27th November 2019, 12.00pm – Kate Laxton, University College London
Unusual techniques for an unusual volcano: monitoring at Ol Doinyo Lengai
Venue: Department of Earth Sciences – Harker II

Abstract not available

# Wednesday 20th November 2019, 1.00pm – Amber Madden-Nadeau, University of Oxford
The magmatic and eruptive evolution of the 1883 explosive, caldera-forming eruption of Krakatau, Indonesia
Venue: Department of Earth Sciences – Harker II

Abstract not available

# Wednesday 13th November 2019, 12.00pm – Bridie Davies, University of East Anglia
Unravelling the Echo Canyon deposit: Explosive-effusive transitional volcanism, Ascension Island, South Atlantic – Insights from the field and the lab
Venue: Department of Earth Sciences – Harker II

Abstract not available

# Wednesday 30th October 2019, 12.00pm – Dan Spencer, University of Oxford
How volcanism controls the interiors of lava-worlds
Venue: Harker 2, Department of Earth Sciences, Downing Street

Jupiter’s moon Io is the most volcanically active body in the solar system, and is part of a growing class of discovered ‘lava-worlds’. Volcanism transports vast quantities of heat from Io’s interior to the surface, a heat transfer mechanism with significant implications for interior structure. We present a model of coupled magmatism and volcanism applied to Io. Intrusive and extrusive rates control the thickness of Io’s crust, whilst continual melting and extraction from the interior, together with suppressed convection could have resulted in a strongly layered mantle. Our results are in agreement with all currently available observations of Io, and present hypotheses readily testable by future missions.

# Wednesday 16th October 2019, 12.00pm – Speaker to be confirmed
New PhD students introductions – Cambridge Volcanology
Venue: Department of Earth Sciences, Tilley Lecture Theatre

Abstract not available

# Wednesday 8th May 2019, 12.10pm – Penny Wieser, University of Cambridge
Tracking chalcophile elements from source to vent at Kilauea Volcano, Hawaii
Venue: Harker 2, Department of Earth Sciences, Downing Street

Kilauea Volcano emits globally significant quantities of S and sulfur loving (Chalcophile) elements into the atmosphere. These emissions have serious implications for respiratory health and agricultural productivity across the island. Yet, the processes controlling the concentration of these elements in erupted melts are enigmatic. Using high precision major and trace element measurements in melt inclusions and matrix glasses, we demonstrate that chalcophile element systematics at Kilauea are controlled by a number of processes, including the presence of sulfide in the mantle source, sulfide-liquid immiscibility during fractionation, sulfide resorption upon eruption, and the degassing of traditionally “refractory” chalcophile elements (e.g. Se). Our conclusions differ substantially from those of previous work, largely because in the literature, chalcophile elements have only been investigated in lava lakes (where the behaviour of S is anomalous due to syn-eruptive degassing).

# Wednesday 1st May 2019, 12.00pm – Professor Christine Lane, Department of Geography, University of Cambridge
Masterclass: An introduction to distal tephrochronology and cryptotephra methods
Venue: Harker 2, Department of Earth Sciences, Downing Street
# Wednesday 5th December 2018, 12.00pm – Thomas J. Aubry, University of British Columbia
Will climate-volcano interactions be modulated by ongoing climate change? Perspective from explosive eruption column rise.
Venue: Harker 2, Department of Earth Sciences, Downing Street

Volcanic eruption plumes reaching the stratosphere result in the formation of long-lived (1-2 years) sulfate aerosols, which interact with Sun and Earth radiation and alter the radiative balance of our planet. In particular, stratospheric volcanic aerosol forcing results in a net cooling of Earth’s surface. As CO2 concentration increases due to anthropogenic emissions, changing weather and climate may affect multiple processes that govern the climatic impact of volcanic eruptions. Will we experience increased or decreased volcanic cooling on a warming Earth? This will be the central question of the seminar. I will focus in particular on how the rise of volcanic plumes and the injection of sulfur gases into the stratosphere may be affected by ongoing climate change.

First, I will discuss the ability of simple (0D, 1D) volcanic plume models to predict volcanic plume heights. Such models commonly require empirical constraints for processes such as the turbulent entrainment of atmosphere into a volcanic column, and are subject to large uncertainties. I will show how recent laboratory experiments and a newly compiled database of eruption source parameters improve constraints and evaluation of volcanic plume models. I will explore the implications of this new work for the prediction of volcanic plume heights and the production of pyroclastic flows, and discuss future steps for producing datasets that will enable a better evaluation of volcanic plume models.

Second, I will use the same volcanic plume models along with climate projections, a volcanic aerosol forcing model, and past records of volcanic sulfur emission to investigate the potential effects of climate change on volcanic plume rise. I will show that reduced volcanic sulfur injections into the stratosphere are projected with ongoing climate change. A novel feedback hypothesis emerging from this work is that volcanic cooling may be reduced on a warming Earth. I will discuss future plans to investigate this feedback in the UK Earth System Model along with feedbacks that could affect different processes governing the climatic impacts of future eruptions.

# Wednesday 28th November 2018, 12.00pm – Ben Ellis, ETH Zurich
Lithium, rhyolites, and the green revolution
Venue: Harker 2, Department of Earth Sciences, Downing Street

Lithium (Li) plays an increasingly important role in society with ever greater reliance on rechargeable batteries for a variety of uses from handheld electronic devices to electric vehicles. Seemingly, there is a relationship between the locations of economic Li deposits and silicic magmatism, however relatively little is known about the behaviour of Li in silicic magmatic systems. This talk will initially discuss how the unusual geochemical properties of Li allow it to remain mobile into the post-eruptive realm and how this mobility obscures ‘true’ magmatic signatures. Subsequently, the talk will focus on situations where Li does preserve information about magmatic and eruptive processes and speculate about what Li may be able to reveal about the magmatic-hydrothermal transition.

# Wednesday 21st November 2018, 12.00pm – Penny Wieser, Emily Mason; University of Cambridge
Measuring gas emissions at the 2018 Leilani Estates eruption, Kilauea
Venue: Harker 2, Department of Earth Sciences, Downing Street

Two graduate students Emily and Penny recount their recent field expedition to the Leilani Estates fissure eruption of Kilauea volcano, Hawai’i.

# Wednesday 14th November 2018, 12.00pm – Craig Walton, Pip Liggins; University of Cambridge
Phosphorous pathways in Deep Time / Atmospheric Fingerprints of Volcanism
Venue: Harker 2, Department of Earth Sciences, Downing Street

Two new graduate students Craig and Pip introduce themselves and their research.

# Wednesday 7th November 2018, 12.00pm – Nick Barber, Johnny Staunton-Sykes; University of Cambridge
tbc // Sulfur isotopes as tracers for stratospheric volcanic sulfur loading
Venue: Harker 2, Department of Earth Sciences, Downing Street

New graduate student Nick Barber will present on his Masters research, GIS applications and mapping the Deccan traps, before introducing his PhD research on metals in volcanic gas emissions.

Second year PhD student Johnny Staunton-Sykes is an atmospheric chemist, and will present on one aspect of his doctoral research, whether mass independent fractionation of volcanic sulfur can be used as a tracer for stratospheric sulfur loading after explosive eruptions.

# Wednesday 24th October 2018, 12.00pm – Evgenia Ilyinskaya, University of Leeds
Globally Significant CO2 Emissions From Katla, a Subglacial Volcano in Iceland
Venue: Harker 2, Department of Earth Sciences, Downing Street

Volcanoes are a key natural source of CO2, but global estimates of volcanic CO2 flux are predominantly based on measurements from a fraction of world’s actively degassing volcanoes. We combine high‐precision airborne measurements from 2016 and 2017 with atmospheric dispersion modeling to quantify CO2 emissions from Katla, a major subglacial volcanic caldera in Iceland that last erupted 100 years ago but has been undergoing significant unrest in recent decades. Katla’s sustained CO2 flux, 12–24 kt/d, is up to an order of magnitude greater than previous estimates of total CO2 release from Iceland’s natural sources. Katla is one of the largest volcanic sources of CO2 on the planet, contributing up to 4% of global emissions from nonerupting volcanoes. Further measurements on subglacial volcanoes worldwide are urgently required to establish if Katla is exceptional, or if there is a significant previously unrecognized contribution to global CO2 emissions from natural sources.

# Wednesday 17th October 2018, 12.00pm – Nick Blegen, University of Cambridge
Volcanic applications for understanding the evolution of human behavior in East Africa
Venue: Harker 2, Department of Earth Sciences, Downing Street

Abstract not available

# Wednesday 10th October 2018, 12.00pm – Sam Poppe, Vrije Universiteit Brussel
An unusual patient: quantifying 3D deformation around analogue magma intrusions by using X-ray Computed Tomography
Venue: Harker 2, Department of Earth Sciences, Downing Street

Magma intrusions grow to their final geometries by straining the Earth’s crust internally and displacing the Earth’s surface. Interpreting that volcanic unrest is key to forecasting a volcanic eruption. While scaled laboratory models enable us to study the relationships between surface displacement and intrusion geometry, past approaches entailed limitations regarding imaging of the model interior or simplicity of the simulated rheology.

This talk presents results from combining state-of-the-art wide beam X-ray Computed Tomography (CT) and Digital Volume Correlation (DVC) to quantify in 4D the deformation induced in laboratory models by an intrusion of a magma analogue (golden syrup) in a granular Mohr-Coulomb host material (sand and plaster). The evolution of the extracted surface deformation and strain field of the entire experimental volume in 3D over time shows how contrasting geometries – cryptodomes, cup shapes, cone sheets and dikes – form in host material of different strength. Moreover, contrasting geometries induce contrasting propagation modes and strain field characteristics in the host.

Our results demonstrate how the combination of CT and DVC can greatly enhance the utility of optically non-transparent crustal rock analogues in obtaining insights into crustal deformation processes. This unprecedented inside perspective helps understanding the limitations of simple elastic rheology used in geodetic and inversion modeling of crustal deformation processes.

# Wednesday 14th June 2017, 1.00pm – Adam Bobbette (University of Cambridge)
Cultures of Forecasting on Mt. Merapi
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Wednesday 24th May 2017, 1.00pm – Marian Holness (University of Cambridge)
Masterclass: Crystal growth kinetics
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Wednesday 10th May 2017, 1.00pm – Peter Baxter (University of Cambridge)
Masterclass: The health impacts of volcanic gases
Venue: Large Lecture Theatre, Geography Department, Downing Site

Abstract not available

# Wednesday 26th April 2017, 1.00pm – Emma Liu (University of Cambridge)
Plume sampling with UAVs on Guatemalan volcanoes
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Wednesday 8th March 2017, 1.00pm – Amy Donovan (UCL)
The 2011 Nabro eruption
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Monday 6th March 2017, 5.30pm – Tamsin Mather, Oxford
Lessons from a restless caldera: multi-parameter studies to understand the past, present and future of volcanic activity at Santorini volcano, Greece
Venue: Harker Room 1, Department of Earth Sciences

Understanding the behavior of magma and hydrothermal fluids at restless calderas is important for many reasons. The interplay between the magmatic and hydrothermal systems at caldera-forming volcanoes is key to interpreting many of the geophysical signals measured at the surface used to understand their subsurface state and structure. Several recent studies have highlighted that structural controls may be important in terms of the movements of both types of fluids in the Earth’s crust below volcanoes with implications including hazard management and geothermal prospecting. Caldera-forming systems are often characterized by eruptive activity covering a wide range of size scales and repose intervals. Understanding how these different scales of volcanism at the same system relate to each other is a key science challenge when seeking to understand these types of volcano. This presentation will explore these issues using examples from the caldera-forming system Santorini volcano, Greece. This is a relatively well-studied system that last erupted significantly about 75 years ago and has recently experienced a period of unusual unrest. Lessons from field mapping and geochemistry, high-resolution digital elevation models, interferometric synthetic aperture radar (InSAR) and degassing surveys and compositions can be brought together to yield insights into the behavior of this and similar volcanic systems.

All welcome to attend, free for members of the Sedgwick Club, £2 for non-members. Refreshments provided!

# Wednesday 22nd February 2017, 1.00pm – Helen Williams (University of Cambridge)
Masterclass: Non-traditional stable isotopes
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Wednesday 15th February 2017, 4.00pm – Dr Rob Green, Bullard Labs
Seismic velocity structure of volcanic rift zones in Iceland
Venue: Marine/Wolfson Building lecture hall, Bullard Labs.

Abstract not available

# Tuesday 14th February 2017, 12.00pm – Saemundur Halldorsson, University of Iceland
Assessing volatile heterogeneity in the Icelandic mantle and transport of volatiles from mantle to surface
Venue: Tilley Lecture Theatre, Department of Earth Sciences

Assessing primary volatile heterogeneity of the mantle beneath Icelandic is an essential requirement before the role of secondary modifications following the release and transport of volatiles from the mantle-crust system, can be evaluated. Recently published stable isotope data (δD, δ15N and δ37C) suggest that the Icelandic mantle samples at least two distinct mantle volatile reservoirs that (i) preserve the geochemical signatures of Earth’s heterogeneous accretion and (ii) show strong evidence for recycled crustal material trapped by the Iceland plume source. Our ongoing work, involving a suite of subglacially erupted basalts along with melt inclusions and sulfide minerals present in mafic minerals from primitive Icelandic basalts, on the stable isotopic composition of H2O (δD), O (δ18O) and S (δ33S, δ34S and δ36S), aims at evaluating volatile heterogeneity present in the Icelandic mantle. By combining our results with trace element ratios (H2O/Ce, Cl/Nb and S/Dy) and radiogenic isotopes (Sr, Nd, Hf and Pb), we can test for modification of mantle-derived stable isotope values and constrain better the degree of volatile heterogeneity in Iceland mantle and, in particular the mantle plume source.

*Sæmundur A. Halldórsson, Jaime D. Barnes, Andri Stefánsson, David R. Hilton, Erik H. Hauri, Edward W. Marshall, 2016. Subducted lithosphere controls halogen enrichments in the Iceland mantle plume source. Geology 44, 679-682, doi:10.1130/G37924.1.

*Sæmundur A. Halldórsson, David R. Hilton, Peter H. Barry, Evelyn Füri and Karl Grönvold, 2016. Recycling of crustal material by the Iceland mantle plume: new evidence from nitrogen elemental and isotope systematics of subglacial basalts. Geochemica Cosmochimica Acta, Volume 176, Pages 206-226. doi:10.1016/j.gca.2015.12.021.

*Lydia J. Hallis, Gary R. Huss, Kazuhide Nagashima, G. Jeffrey Taylor, Sæmundur Ari Halldórsson, David R. Hilton, Mike J. Mottl and Karen J. Meech 2015. Evidence for primordial water in Earth’s deep mantle. Science. Volume 350, 6262, 795-797, doi: 10.1126/science.aac4834.

# Wednesday 8th February 2017, 1.00pm – John Maclennan (University of Cambridge)
Masterclass: Calculating P-T-t paths in basalts
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Thursday 26th January 2017, 5.30pm – Christine Lane, Department of Geography, University of Cambridge
Late Quaternary tephrostratigraphies from East African lakes
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

This talk is part of the Quaternary Discussion Group (QDG)

Understanding the spatial and temporal variability of climate forcing and palaeoenvironmental response across a continent as climatically diverse as Africa relies upon comparison of data from widespread palaeoenvironmental archives. Accurate, precise and independent chronologies for such records are essential; however this remains a challenge in many environments and often prevents the valid comparison of detailed palaeo-proxy records. Many studies have now shown that volcanic ash (tephra) can be detected in terrestrial and marine sediments thousands of kilometres from their source, often as microscopic or “cryptic” layers. As well as offering opportunities for both direct (e.g. by 40Ar/39Ar methods) and indirect (e.g. by associated 14C dates) dating of the sediment sequence, tephra layers can provide stratigraphic tie-lines between archives, facilitating precise correlations at single moments in time. Furthermore, where two or more tephra layers are co-located in multiple records, rates of change can be compared within a period of equivalent duration, even in the absence of absolute age estimates.
Investigations into the presence of visible and non-visible (crypto-) tephra layers within lacustrine palaeoenvironmental records of the last ~150 ka BP from across East Africa are revealing the potential for this approach to (i) correlate palaeoclimate archives from across and beyond tropical Africa within a regional tephrostratigraphic framework; (ii) provide age constraints for individual core chronologies, in particular beyond the limits of radiocarbon dating; and (iii) increase our knowledge of the history of Late Quaternary explosive volcanism in East Africa.

# Wednesday 25th January 2017, 1.00pm – Celine Vidal (University of Cambridge)
The 1257 Samalas eruption
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Wednesday 18th January 2017, 4.00pm – Freysteinn Sigmundsson (Nordic Volcanological Centre, Institute of Earth Sciences, University of Iceland)
TBA
Venue: Wolfson Lecture Theatre, Bullard

Abstract not available

# Tuesday 17th January 2017, 12.00pm – Freysteinn Sigmundsson (Nordic Volcanological Centre, Institute of Earth Sciences, University of Iceland)
TBA
Venue: Tilley Lecture Theatre, Earth Sciences Department

Abstract not available

# Monday 28th November 2016, 1.00pm – Kathy Cashman (University of Bristol)
Rethinking volcanism from a trans-crustal perspective
Venue: MR5, Centre for Mathematical Sciences

Abstract not available

# Monday 14th November 2016, 1.00pm – Zoja Vukmanovic (University of Cambridge, Earth Sciences)
The importance of compaction in the formation of adcumulates in the Skaergaard intrusion, East Greenland
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Monday 14th November 2016, 1.00pm – Gautier Nicoli (University of Cambridge)
Crystal settling and convection: perspectives from the Totternish Sill Complex & Komatiite Lava flow
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Tuesday 10th March 2015, 1.00pm – Dr. David Neave
Saksunarvatn melts
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Wednesday 25th February 2015, 1.00pm – Prof. Herbert Huppert
The propagation of gigantic volcanic eruption clouds through the atmosphere
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Thursday 19th February 2015, 2.15pm – Nahum Clements, Dept of Earth Sciences
Gas Monitoring at Holhraun
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Thursday 20th February 2014, 4.30pm – Dr. Ian Skilling
The Siđa Formation of SE Iceland: Emplacement Processes and Depositional Environment
Venue: Harker 2, Earth Sciences Department

The Siđa Formation consists of at least seven stacked sheet-like basaltic sequences comprising basal diamict, overlying largely degassed lava and uppermost hyaloclastite. The maximum thickness of each repeated stack is about 70m, but is widely variable, and not all units are always present. The lava-hyaloclastite contact locally displays spectacular flame-like intrusions (viscous fingers) of lava up to several metres in length into the overlying hyaloclastite. There are three published models for the environment of deposition of this formation: on the continental shelf (Bergh and Sigvaldason, 1991), beneath >900m thick ice (Smellie, 2008) and beneath thin (<200m) ice but with subaerial vent conditions (Banik et al., 2013). This talk will review the evidence for these environments and their associated emplacement mechanisms and present some new studies on the lava fingers. I argue that the key to understanding the formation is magma-ice interaction during voluminous fissure eruptions along the thinned margins of large ice sheets.

# Thursday 6th February 2014, 1.00pm – Tehnuka Ilanko, Geography Department
Periodicity in gas emissions from Erebus lava lake
Venue: Harker 2, Earth Sciences Department

Abstract not available

# Friday 22nd November 2013, 3.00pm – Dr Alexa Van Eaton (U.S Geological Survey, Vancouver)
Combining field observations and the volcanic plume model ATHAM to examine “dirty thunderstorm” dynamics of ancient and modern eruptions
Venue: Seminar Room, Main Geography Department Building, Downing Place

Abstract: What do hailstone formation, deep moist convection, and lightning-producing charge separation have to do with explosive volcanism? Until relatively recently, these concepts were exclusive to the meteorology community. However, they are currently known to play important roles in the development of volcanic clouds. This talk explores how the hybrid concept of powerful volcanic eruptions as ash-laden “dirty” thunderstorms is helping to resolve some of the more peculiar behaviors inferred from super-eruption deposits in New Zealand and directly observed during recent activity in the Cascades and Alaska.

# Thursday 24th October 2013, 1.00pm – Nial Peters (University of Cambridge)
Fire, Ice and Non-Linear Time Series Analysis: Cycles in Motion of the Erebus Lava Lake
Venue: Harker 2, Earth Sciences Department

Despite being in quick succession from Kayla’s talk Nial will be giving a lunchtime talk on research into the Erebus lava lake, before hopefully heading to Antarctica in the coming weeks.

Feel free to bring along your lunch.

# Monday 21st October 2013, 6.00pm – Kayla Iacovino (University of Cambridge)
The Mt. Paektu Geoscientific Experiment: Tales from Fieldwork in North Korea
Venue: Harker 2, Earth Sciences Department

To kick off the new academic year for CVG Kayla will be givine a short talk reporting on her recent fieldwork in North Korea.

We will be heading to the pub, and then out for dinner, afterwards.

Contact me (David Neave) if you have difficulty getting into the building.

# Tuesday 11th June 2013, 4.30pm – Marie Edmonds
Unlocking the secrets of melt inclusions at Kilauea Volcano
Venue: Tilley Lecture Theatre, Earth Sciences Department

Melt inclusions from 25 eruptions of Kilauea Volcano over the last 600 years highlight the important processes of fractionation, mixing and degassing prior to eruption. The sampled eruptions span a large range of styles, ranging from effusive through to transient explosive and fountaining. The data show that there is a statistical difference in the geochemistry between the different styles, and through different time periods at Kilauea, suggesting that the explosivity of melts might be “set” right from the point of separation from the mantle source. We look at one fountaining eruption in detail (the 1959 Kilauea Iki eruption) to investigate how fountains are triggered. Inputs of hot, primitive, gas-rich melts mix with cooler, stored melts, causing rapid vesiculation, leading to fountains. Along the way, we see how melt inclusions are dramatically altered by processes such as post-entrapment crystallization and the development of a shrinkage bubble, illustrating some of the pitfalls of melt inclusion work.

# Thursday 23rd May 2013, 1.00pm – Katherine Daniels
Thermal models of dyke intrusion during development of Continent-Ocean Transition
Venue: Harker II, Geology Department

A consensus has emerged in recent years from a variety of geoscientific disciplines that extension during continental rifting is achieved only partly by plate stretching: dyke intrusion also plays an important role. Magma intrusion can accommodate extension at lower yield stresses than are required to extend thick, strong, unmodified continental lithosphere mechanically, thereby aiding the breakup process. Dyke intrusion is also expected to thermally modify the rheology of the extending plate, but the extent of its influence and the timescales over which it operates are poorly understood.

To address this issue, a numerical solution to the heat flow equation is developed here to quantify the thermal effects of dyke intrusion on the continental crust during rifting. Finite difference models demonstrate that magmatic extension rate exerts a first order control on crustal thermal structure.Once dyke intrusion supersedes faulting and stretching as the principal extensional mechanism the crust will heat and weaken rapidly (<<1 Ma). The thermal models are benchmarked against a priori constraints on crustal structure and dyke intrusion episodes in Ethiopia.

# Wednesday 7th November 2012, 5.30pm – Nial Peters and Yves Moussallam
Eruption en tu boca! Chile 2012 Volcanic monitoring at Villarrica, Puyehue and Lascar volcanoes
Venue: Harker II, Geology Department

Abstract not available

# Tuesday 30th October 2012, 7.30pm – Yves Moussallam and Nial Peters
Organised by Cambridge University Caving Club
Volcanic Caves
Venue: ALB, Clare Hall, Herschel Road

Abstract not available

# Wednesday 24th October 2012, 5.00pm – Brendan McCormick and Lois Salem
Santorini and CVG field trip to the Etna & the Aeolian
Venue: Harker II, Geology Department

Brendan will be talking about his recent fieldwork on Santorini with colleagues from Oxford and Lois about our recent CVG field trip to the Etna & the Aeolian Islands The talks will be followed by a glass of wine in the Common Room at 17:30 ish. The keen amongst us can then head off to a pub and/or for a curry after.

# Friday 7th September 2012, 4.00pm – Dr Chiara Maria Petrone (University of Cambridge)
The volcanic activity of Stromboli volcano: magma dynamics of a steady-state volcano
Venue: Harker II, Geology Department

Abstract not available

# Tuesday 12th June 2012, 1.00pm – David Neave & Margaret Hartley
The Record of Deep Magmatic Processes in the AD 1783 Laki Fires Eruption, Iceland.
Venue: Tilley Lecture Theatre, Earth Sciences Department

A report on the results of studies into crystal-melt relationships, concurrent mixing and crystallisation and ongoing investigation of deep degassing behaviour.

# Thursday 24th May 2012, 5.00pm – Sara Mana (Rutgers University)
Rifting of a Continent: the North Tanzanian Divergence Zone, East African Rift System
Venue: Harker II, Geology Department

The role of magmatism in continental rift initiation and evolution is of much debate. Our research focuses on a section of the magmatic-rich eastern branch of the East African Rift in Northern Tanzania that depicts the complex early stage of tectono-magmatic rift evolution. This area, the North Tanzania Divergence (NTD), is currently volcanically active with a magmatic history that initiated in the Miocene, prior to documented extension. Some of the NTD volcanoes are among Earth’s largest (Kilimanjaro, Ngorongoro), and have produced a diverse array of lavas from basalt to rhyolite, trachyte, nephelinite to phonolite and carbonatite. Their distribution is widespread, both N-S along the rift axis and E-W across the valley floor and onto the adjacent rift margins.

The oldest NTD magmatism is recorded at the centrally located Essimingor volcano. We report new 40Ar/39Ar ages, major and trace element analyses and Sr-Nd-Pb radiogenic isotopic signatures on well-located lavas representing the observable variation in lithology and stratigraphy from the S and SW slopes of Essimingor. Laser-incremental heating 40Ar/39Ar analyses of whole rock, matrix and nepheline separates yield plateau ages ranging from 5.76±0.02 Ma to 5.91±0.01 Ma.

Essimingor major element data define narrow compositional variations consistent with fractional crystallization. Open system processes of mixing or contamination are inferred from an increase in Sr isotopic values with indices of fractionation. Ce/Pb varies over a large range (59 to 7), the lower end of which implies crustal assimilation that overprints the mantle signature. An FC versus AFC process has therefore been modeled. The Sr-Nd-Pb isotopic values indicate the involvement of a HIMU-like component. Trace element abundances of the more primitive samples (MgO >9 wt%) suggest partial melting of a metasomatized lithospheric mantle peridotite characterized by the presence of residual garnet and phlogopite combined with minor amphibole and apatite. The coexistence of garnet and phlogopite in the source suggests melting at ~80–150 km depth, consistent with the base of the lithosphere in the eastern branch identified using Rayleigh wave tomography (120-160 km; Weeraratne et al. 2003) and indicating that Essimingor represents the initial phase of lithospheric removal.

Ongoing analysis of younger NTD volcanoes should help constrain the timing and location of the progressive lithospheric thinning during early rifting.

# Monday 21st May 2012, 2.15pm – Dr Mario Montopoli, Dept. Geography, University of Cambridge,
This talk is part of the Centre for Atmospheric Science seminars series
Microwave remote sensing of volcanic ash clouds.
Venue: Unilever Lecture Theatre, Department of Chemistry

Plinian and sub-Plinian volcanic explosive eruptions probably represent one
of the most devastating natural events for the surrounding environment,
endangering people’s lives and property. Explosive volcanic eruptions can
significantly influence climate as well as cloud formation and global
circulation through atmospheric transport. Volcanic ash clouds are also an
increasing hazard to aviation safety because of growing airline traffic.

From the first rudimental visual inspections at the times of Pliny the

Elder, the human curiosity and its needs to find effective countermeasures
to these extreme volcanic episodes has never ceased, even though their
(fortunate) rarity makes the scientific research quite challenging.

Nowadays, visual inspections are accompanied by sophisticated measurements
made by direct analysis and from remote sensors. Microphysical
characterization of the Plinian volcanic ash plumes is usually carried out
by analyzing tephra deposits and ash sedimentation at ground. This analysis
may only give indirect information on the ash cloud composition as several
processes can take place during the ash fallout. On the other hand,
real-time monitoring of a volcano eruption is not always possible by
conventional visual inspections due to the usual low optical visibility.
Finally, airborne flights within ash plumes using sample probes, as done
for water clouds, are considered too dangerous for the safety reasons
previously mentioned. Remote sensing techniques represent a unique tool to
be exploited for this scope. They allow observing the evolution of some key
parameters of volcanic eruptions without a direct interaction between the
measurement system and the target of the measure. Electromagnetic or
acoustic waves are usually used to this aim. Among the available remote
sensing techniques, satellite-based approaches, using multi-frequency
radiometers with visible and infrared channels, have demonstrated to be a
valuable supports to the monitoring of ash clouds. Moreover, measurements
in the visible spectral window are not always available due to its solar
illumination dependence and the optical thickness of volcanic clouds can
severely impair the sounding of lower cloud layers.

In contrast with satellite methodologies, ground-based microwave scanning
weather radars can gather three-dimensional information of ash-cloud
scattering volumes with ranges up to several hundreds of kilometers, in all
weather conditions, at a fairly high spatial resolution (hundreds of
meters) and with a repetition cycle of few minutes. So far, these systems
have been mainly used for meteorological operational forecasts and for
observing of some small number of volcanic areas which can be monitored by
previously installed instruments. There are also several open issues about
microwave weather radar capabilities to detect and quantitatively retrieve
ash cloud parameters.

After a basic introduction on remote sensing principles, the presentation
will focus at illustrating and assessing the potential and limitation of
microwave remote sensing of Plinian and sub-Plinian volcanic eruption. This
will be done using examples from both ground based radar and satellite
radiometers data, collected after the 2010 and 2011 eruptions in Iceland.
Some quantitative estimates of ash category and ash concentration will be
shown together with explanations of the algorithms used.

# Friday 18th May 2012, 1.00pm – Clive Oppenheimer
Volcanoes on borders
Venue: Seminar room, Departement of Geography main building, Downing Site

I’ll give a report of recent visits to two interesting volcanoes, both situated on international borders: Paektu/Changbai (Democratic People’s Republic of Korea, aka North Korea, and China) and Nabro (Eritrea and Ethiopia). The borders aspect does add complexity to risk management and emergency response issues, which I shall touch on, but I’ll mostly focus on the travelogue.