Past seminars

Return to the list of forthcoming seminars.

# 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)
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)
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.