Upcoming Talks (<front>)

Abstract not available

• Speaker: James McCann
• Friday 21 March 2025, 16:00-17:00
• Venue: Tea Room, Old House.
• Series: Bullard Laboratories Tea Time Talks; organiser: David Al-Attar.

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Abstract not available

• Speaker: Ali Mashayek (University of Cambridge)
• Thursday 05 June 2025, 11:30-12:30
• Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
• Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.

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Abstract not available

• Speaker: Dan Toy, IEEF
• Monday 24 March 2025, 11:30-12:30
• Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
• Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.

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Decarbonising our energy and transport systems is a major challenge for addressing the climate crisis. This will require a whole range of different raw materials including critical elements associated with LCT granites and pegmatites (Linnen et al., 2012). However, at the moment we are lacking a solid understanding of how and where LCT melts form which also means reliable geological exploration models don’t exist.

Geochemical characterisation of LCT granites and pegmatites shows (re-)melting of continental crust as the source (Černý et al., 2012). Which means metamorphism and partial melting are an essential process in the formation of LCT melts. The classical model assumed the onset of muscovite melting to be the key process. As micas are known hosts of critical elements (e.g., Li, Be, V, Rb, Cs, Sn, Ta, W) and would release their trace elements into a relatively small volume of melt, which creates enriched melts. These melts would be further enriched during fractional crystallisation finally creating element concentrations of economic interest. Contrary to that theory a study on whole rock compositions (Wolf et al., 2018) and of metamorphic micas from greenschist to granulite facies conditions (Kunz et al., 2022) have shown that biotite is the major host of elements associated with LCT melts. This raises the question if (1) biotite melting might be the essential process for producing LCT enrichment and (2) under which partial melting conditions this would create the highest critical element enrichment.

Over the last couple of years, a number of studies have started to address these questions ranging from natural observations to modelling and partial melting experiments. Some of the key questions and challenges at the moment are: (1) is an enriched sedimentary source needed?; (2) what is the importance of the melting conditions/reaction for enrichment?; (3) overcoming limitations of natural and experimental research approaches and (4) developing robust input parameters for partial melting modelling.

• Speaker: Dr Barbara Kunz - The Open University
• Monday 17 March 2025, 18:00-19:00
• Venue: Harker 1 lecture room, Department of Earth Sciences, Downing Site.
• Series: Sedgwick Club talks; organiser: Susannah Scott.

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Critical Materials are a longstanding concept, with the United States referring to “Strategic Minerals” in 1917 as those for which domestic supplies were inadequate in quantity, quality, or both. In recent decades, awareness of Critical Materials has increased – from the “Rare Earth Crisis” from 2010 to 2015, and more from the vulnerabilities of global supply chains exposed during the COVID -19 pandemic and conflict in Ukraine. Not only are these Critical Materials important for general functioning and security of nations; there are additional pressures being placed particularly on metals value chains from the need for metals for energy transition and sustainable development ambitions.

Circularity strategies have been advocated as a mechanism to enhance critical raw materials (CRM) security in the UK and Europe. Especially in the context of reducing import reliance and thus decreasing supply risk by having domestic/localised cycling of key metals and materials. Circular Economy (CE) principles-based systems may initially appear to contradict continuation of a primary raw materials extractive sector. However, there is a growing body of research examining the development of CE practices in the mining industry, in order to increase resource efficiency by understanding better potential co- and by-products, more efficient extraction and processing, and use/ re-use of waste products.

This talk explores the application of circular economy principles to the mining sector, with a focus on critical metals projects in Cornwall, and more broadly how these principles interface with geology and geoscience’s place in developing responsible resource management systems.

• Speaker: Dr Eva Marquis - University of Exeter
• Monday 10 March 2025, 18:00-19:00
• Venue: Harker 1 lecture room, Department of Earth Sciences, Downing Site.
• Series: Sedgwick Club talks; organiser: ss2849.

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3D full waveform inversion (FWI) has been applied to the seismic refraction data of the MARINER (Mid-Atlantic Ridge INtegrated Experiment at Rainbow) experiment to create a robust high-resolution model of the seismic velocity structure of the Rainbow massif. The Rainbow massif is an oceanic core complex located on a non-transform discontinuity (NTD) in a magma-starved region of the mid-Atlantic Ridge at 36ºN. Despite the low magmatic input, the core complex hosts a high-temperature hydrothermal vent field  (>340°C) that requires a long-lived magmatic heat source. The FWI results show that deep within the massif, ∼3-8 km below the seafloor, lies a low-velocity body that represents a partially molten sill complex. The sill complex extends north to the AMAR Minor N segment suggesting an increased magmatic input into this segment, forcing the NTD to migrate southwards. Extensive magmatic intrusion into the core complex was likely responsible for termination of slip on the detachment fault. We model hydrothermal fluid flow inside the Rainbow massif using the Imperial College Finite Element Reservoir Simulator (IC-FERST). The model geometry, thermal properties, flow properties and boundary conditions are informed by the seismic constraints. We show that the high temperatures within the core of the Rainbow massif prevent serpentinization from taking place and govern the location of the serpentinization front.

• Speaker: Michele Paulatto, Imperial College London
• Wednesday 12 March 2025, 14:00-15:00
• Venue: Wolfson Lecture Theatre.
• Series: Bullard Laboratories Wednesday Seminars; organiser: Tom Merry.

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Abstract not available

• Speaker: Min Huang
• Friday 07 March 2025, 16:00-17:00
• Venue: Tea Room, Old House.
• Series: Bullard Laboratories Tea Time Talks; organiser: David Al-Attar.

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In subduction zones, upper-plate elastic rock properties play a major role in controlling megathrust fault dynamics (Sallarès & Ranero 2019; Prada et al., 2021; Ulrich et al., 2022). The variations of these properties in the downdip direction are influenced by increasing confining pressure with depth, forming a global depth-dependent pattern (Sallarès & Ranero 2019). However, the understanding of how these properties vary along-strike, especially above the interplate, where elastic energy is stored during interseismic cycle, remains unclear. Here we present 3D tomographic constraints on the velocity structure of the upper plate as well as the inter-plate geometry offshore the Ecuadorian-Colombian margin. The study area has been the locus of large megathrust tsunamigenic earthquakes, including the seventh largest in history (1906 Mw~8.8 Esmeraldas), but elastic properties above the megathrust are not mapped hitherto. Here we use 3D wide-angle seismic (WAS) dataset acquired in 2005 during the ESMERALDAS survey and multichannel seismic (MCS) lines to integrate tectonic information to our tomographic results. WAS data were acquired with 26 ocean bottom seismometers from which we picked travel times of P-waves refracted through the upper and lower plates, as well as P-wave reflections at the interplate. We invert travel times with a 3D joint reflection and refraction travel time method (Melendez et al., 2015) following a Monte Carlo approach to provide uncertainties on model parameters.The resulting model shows the 3D P-wave velocity (Vp) structure of the upper and lower plates as well as the geometry of the interplate reflector. Additional elastic parameters such as rigidity (i.e., shear modulus) were derived using empirical relationships between Vp, Vs, and density. Downdip variations in rigidity align with the inferred global trend. However, rather than being laterally consistent, elastic properties exhibit remarkable variations along-strike within the rupture area of the largest recorded earthquakes. MCS sections in the study area depict a complex interaction between crustal-scale faults. This interaction has been proposed to control the seismogenic behavior of the subduction zone in this region, promoting the occurrence of confined ruptures (Collot et al., 2004). A comparison between MCS reflection lines and tomographic results reveals a correlation between localized low-rigidity upper-plate regions and the interaction of such crustal-scale faulting. The presence of low rigidity areas above the interplate may enhance coseismic slip, while locally damaged regions in the upper-plate may favour inelastic deformation during coseismic events, promoting localised seafloor uplift. In contrast to downdip elastic rock variations above the upper-plate, our results indicate that along-strike variations are dependent on the interaction of crustal-scale structures and, consequently, on local geology.

• Speaker: Manel Prada -- Institute of Marine Sciences, Spanish National Research Council (CSIC)
• Wednesday 05 March 2025, 14:00-15:00
• Venue: Wolfson Lecture Theatre.
• Series: Bullard Laboratories Wednesday Seminars; organiser: ChuanChuan Lu.

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Aquifer Thermal Energy Storage (ATES) is an underground thermal energy storage technology that provides large capacity (of order MWth to 10s MWth), low carbon heating and cooling to the built environment. Heating and cooling currently produces 23% of the UK’s greenhouse gas emissions. ATES can be a key technology for the UK to meet its net zero targets. ATES offers a higher overall coefficient of performance compared to conventional, open-loop shallow geothermal systems: waste heat and cool is captured and stored underground as warm and cool water, so less electrical energy is required by a heat pump to provide heating, and cooling can be delivered directly without the need for a heat pump.

ATES could make a significant contribution to decarbonising UK heating and cooling, but uptake is currently very low with eleven systems meeting of UK heating demand and 79 of cooling demand. Widespread deployment in the UK offers a 16-41% reduction in carbon emissions for heating, and 86-94% reduction for cooling, compared to equivalent ground- or air-sourced heat pump systems. A key barrier to increasing uptake is lack of awareness of the technology.

• Speaker: Matthew Jackson, Imperial College London
• Thursday 13 March 2025, 11:30-12:30
• Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
• Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.

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Satellite and field observations show that the West Antarctic Ice Sheet (WAIS) is currently undergoing rapid ice loss, thereby increasingly contributing to global sea-level rise. The direct observational record, however, spans just a few decades, raising the question whether this “snapshot” of ice-sheet changes is representative or exceptional in a longer-term context. The only reliable method to establish the long-term framework of WAIS variability and, thus, to evaluate, if present ice loss is related to human-induced global warming, is the reconstruction of past ice-sheet configurations from the geological record. Here I will demonstrate how research on the marine geological imprint left by the ice sheet on the West Antarctic continental margin has improved our understanding of past and present WAIS dynamics. This newly acquired knowledge will help to evaluate the reliability of numerical models in simulating WAIS dynamics and, thus, improve model-based predictions of future ice loss and associated global sea-level rise.

• Speaker: Dr Claus-Dieter Hillenbrand, British Antarctic Survey
• Monday 03 March 2025, 18:00-19:00
• Venue: Harker 1 lecture room, Department of Earth Sciences, Downing Site.
• Series: Sedgwick Club talks; organiser: ss2849.

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Magnitude ~ 5 earthquakes are often observed at caldera volcanoes undergoing unrest. These earthquakes stand out in regional and teleseismic moment tensor catalogues for their shallow depths and non-double-couple source mechanisms. Intriguingly, the orientation of the moment tensor (vertical-dilatational or vertical-compressional) appears to correlate with the stage of volcanic unrest (inflation building up to eruption, or deflation as magma leaves the edifice), but we don’t yet have a general understanding of what source processes lead to their distinctive nature.

In this talk I will explore how local measurements of such earthquakes at Bárðarbunga caldera, central Iceland, can be used to investigate this further. Bárðarbunga has hosted the longest sequence of such anomalous earthquakes observed at any volcano globally, and in 2014-15 hosted a spectacular eruption that featured more than 70 of these Mw 5+ events over a period of just 6 months. Analysis of detailed observations of seismicity and ground deformation delivered important new constraints on models of the caldera system and ring faults, but also new questions. Since 2015 the edifice has been re-inflating, accompanied by around 1-2 large earthquakes per year. We have sought to exploit this by supplementing the long-running regional network with temporary dense deployments of seismometers above the ice-filled caldera, to provide further improved constraints on earthquake locations and focal mechanisms. I will describe the 10’s of thousands of earthquakes we have located from these few months of data, and the new insights they provide into caldera ring fault seismicity at Bárðarbunga.

• Speaker: Tom Winder ( University of Iceland)
• Wednesday 26 February 2025, 14:00-15:00
• Venue: Wolfson Lecture Theatre.
• Series: Bullard Laboratories Wednesday Seminars; organiser: ChuanChuan Lu.

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Abstract not available

• Speaker: Sam Clarke, IEEF
• Thursday 06 March 2025, 11:30-12:30
• Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
• Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.

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Reducing reliance on fossil carbon is central to the concepts of sustainable development and material stewardship. Whereas decarbonization of the energy sector is feasible through the development of renewable energy, the chemicals sector needs carbon as a building block. The lasting and growing demand for this embedded carbon, especially for production of polymers, must be met in the future through utilization of renewable feedstocks such as biomass, CO2 and recycling of carbon-containing waste. In this context, the transition from fossil to renewable polymers provides a major challenge. Advances in renewable polymers will be exemplified through case studies of two of the most promising bio-based platforms for plastics: lactic acid (LA) and hydroxymethylfurfural (HMF).

• Speaker: Professor Matthew Davidson, Bath Institute of Sustainability and Climate Change
• Thursday 27 February 2025, 11:30-12:30
• Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
• Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.

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Magnitude ~ 5 earthquakes are often observed at caldera volcanoes undergoing unrest. These earthquakes stand out in regional and teleseismic moment tensor catalogues for their shallow depths and non-double-couple source mechanisms. Intriguingly, the orientation of the moment tensor (vertical-dilatational or vertical-compressional) appears to correlate with the stage of volcanic unrest (inflation building up to eruption, or deflation as magma leaves the edifice), but we don’t yet have a general understanding of what source processes lead to their distinctive nature.

In this talk I will explore how local measurements of such earthquakes at Bárðarbunga caldera, central Iceland, can be used to investigate this further. Bárðarbunga has hosted the longest sequence of such anomalous earthquakes observed at any volcano globally, and in 2014-15 hosted a spectacular eruption that featured more than 70 of these Mw 5+ events over a period of just 6 months. Analysis of detailed observations of seismicity and ground deformation delivered important new constraints on models of the caldera system and ring faults, but also new questions. Since 2015 the edifice has been re-inflating, accompanied by around 1-2 large earthquakes per year. We have sought to exploit this by supplementing the long-running regional network with temporary dense deployments of seismometers above the ice-filled caldera, to provide further improved constraints on earthquake locations and focal mechanisms. I will describe the 10’s of thousands of earthquakes we have located from these few months of data, and the new insights they provide into caldera ring fault seismicity at Bárðarbunga.

• Speaker: Tom Winder, University of Iceland
• Monday 24 February 2025, 14:00-15:00
• Venue: Wolfson Lecture Theatre.
• Series: Bullard Laboratories Wednesday Seminars; organiser: ChuanChuan Lu.

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Abstract not available

To meet with the speaker, contact Ali Mashayek (am3158@cam.ac.uk)

• Speaker: Dr Sasha Montelli
• Tuesday 18 March 2025, 12:00-13:00
• Venue: Department of Earth Sciences, Tilley Lecture Theatre.
• Series: Department of Earth Sciences Seminars (downtown); organiser: Ali Mashayek.

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Come along to hear some of your favourite Part III students talk about what they did on internships and research placements this summer. From corals to chondrites we’ve got it all! Also an excellent way to find out about opportunities you could apply for when you’re not trudging through the rain on field trips. Speakers are: Alex C, Jenny D, Susannah S, Rosa W, Gio B, Rory M, Erica M, Zara C and Pippa L!

• Speaker: Part 3 students
• Wednesday 19 February 2025, 18:00-19:00
• Venue: Harker 1 lecture room, Department of Earth Sciences, Downing Site.
• Series: Sedgwick Club talks; organiser: ss2849.

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In this talk I’ll synthesize recent research interrogating how variations in weathering regimes and sediment deposition have impacted the chemistry of igneous rocks. In particular, I will focus on a particular class of granites (often termed “S-type”) which form via partial melting of siliciclastic sedimentary rocks and are uniquely suited to capture how the chemical consequences of sedimentary incorporation into magmas have varied throughout Earth history. I will focus on how enhanced organic matter and clay deposition at various periods in Earth history are reflected in the chemistry of the granites and the implications these variations have for our understanding of the oxygenation of Earth’s atmosphere and the occurrence of Li mineral deposits.

• Speaker: Claire Bucholz, Caltech
• Tuesday 11 March 2025, 12:00-13:00
• Venue: Department of Earth Sciences, Tilley Lecture Theatre.
• Series: Department of Earth Sciences Seminars (downtown); organiser: Dr Rachael Rhodes.

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Abstract not available

To meet with the speaker, contact Ali Mashayek (am3158@cam.ac.uk)

• Speaker: Dr Sasha Montelli
• Tuesday 18 March 2025, 12:00-13:00
• Venue: Department of Earth Sciences, Tilley Lecture Theatre.
• Series: Department of Earth Sciences Seminars (downtown); organiser: Ali Mashayek.

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Faults in the brittle crust lie at any orientation to the far-field stress. However, laboratory experiments designed to investigate earthquake physics commonly simulate favorably oriented faults, potentially overlooking the complexity of natural fault behavior. Here, we assess the role of stress field orientation in fault reactivation and earthquake precursors by conducting triaxial sawcut experiments with laboratory faults oriented at different angles to the maximum principal stress, ranging from 30° to 70°. The samples were instrumented with strain gauges and piezoelectric sensors. Laboratory well-oriented faults describe a rather simple system in which the elastic energy is stored via the deformation of the surrounding host rock during the inter-seismic period and released via on-fault slip during the co-seismic phase with associated precursor acoustic activity. Consistent with previous laboratory data, an abrupt increase in the on-fault acoustic emission rate occurs shortly before the laboratory earthquake. A more complex picture emerges when deforming laboratory misoriented faults. Particularly, acoustic emissions and strain gauge data indicate that when the fault is misoriented, off-fault permanent deformation occurs well before fault reactivation. The stress state in the host rock surrounding the fault is indeed far beyond the one required for the onset of inelastic deformation. In this case, acoustic activity distributed in the rock volume during the pre-seismic phase is associated with permanent deformation in the critically stressed host rock and is not a direct precursor to the following laboratory earthquake. Unlike well-oriented faults, laboratory misoriented faults lack detectable seismic precursors. The laboratory-observed increase in acoustic activity prior to, but not precursor of, misoriented fault reactivation impacts our understanding of earthquake precursors in natural faults.

• Speaker: Carolina Giorgetti, ENS Paris
• Wednesday 19 March 2025, 14:00-15:00
• Venue: Wolfson Lecture Theatre.
• Series: Bullard Laboratories Wednesday Seminars; organiser: Adriano Gualandi.

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Catastrophic failure is the end result of progression and localisation of damage towards brittle failure on a variety of system scales in the Earth. However, the factors controlling this evolution, and that of the resulting seismicity, are not well constrained.  We address the question of how to relate the two, and the extent to which they can be controlled by feedback on the seismicity rate in a scale model experiment on a small rock sample deformed in a synchrotron. We image the underlying damage using x-rays and detect acoustic emissions, and show how they change during localisation, from distributed tensile cracking to a localised shear band containing a mixture of tensile cracking, grain rotation, and grain boundary shear, with shear becoming increasingly dominant and ultimately frictional sliding on a contiguous fault.  We confirm that using continuous servo-control based on acoustic emission event rate not only slows down deformation compared to standard constant strain rate loading, but also suppresses events of all sizes, including extreme events. We use this evolution to develop a mixture model for the stress history from damage mechanics, and find it is independently consistent with the observed stress history and acoustic emission statistics. Our results imply that including seismic event rate control may improve risk management of induced seismicity compared to feedback on the maximum magnitude alone. 

• Speaker: Ian Main, University of Edinburgh
• Wednesday 19 February 2025, 14:00-15:00
• Venue: Wolfson Lecture Theatre.
• Series: Bullard Laboratories Wednesday Seminars; organiser: Adriano Gualandi.

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