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Valley networks in mountain ranges record the interactions between climate, tectonics, and geology. While drainage network analysis has transformed our understanding of these interactions in subaerial settings, the landscape evolution of ice-covered orogens is poorly known. The Gamburtsev Subglacial Mountains are a 600 km-long mountain range situated beneath the East Antarctic Ice Sheet, the largest ice sheet on Earth. These mountains are thought to have been an important nucleation site for the ice sheet approximately 34 million years ago and are now buried beneath 2 km of ice. Airborne geophysical surveying has revealed that the Gamburtsevs are characterised by a rugged, incised landscape, but their geological structure and uplift history remain enigmatic.

This talk will explore how radio-echo sounding (radar) data can be used to extract valley networks and longitudinal profiles from the Gamburtsevs. We combine analysis of these valley profiles with gravity and magnetic anomalies to infer details of the tectonic and geomorphic development of the mountains. For example, channel steepness indices and their relationship with magnetic anomalies allow us to confirm the positions of major geological boundaries that may date back to Gondwana assembly. Drainage basin analysis and stream power incision modelling are used to show that the morphology of the valley networks is largely consistent with fluvial incision that occurred prior to Eocene/Oligocene glaciation. This relic landscape is now preserved beneath the non-erosive centre of the East Antarctic Ice Sheet. Tectonic geomorphic analysis suggests that the routing of Gamburtsev fluvial systems was likely influenced by extensional faulting within East Antarctica, which may have controlled pre-glacial base level and the locations of interior sediment depocentres. We use these findings, together with independent estimates of denudation rates, to evaluate competing scenarios for the mechanism(s) and timing of Gamburtsev mountain uplift and valley incision. Finally, through numerical ice-sheet modelling, we examine how the uplift of these mountains may have played a crucial role in governing the nature and timing of the initial growth of the East Antarctic Ice Sheet.

Speaker: Guy Paxman (Durham)
Wednesday 06 May 2026, 14:00-15:00
Venue: Wolfson Lecture Theatre.
Series: Bullard Laboratories Wednesday Seminars; organiser: Alice Turner.

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Categories: Upcoming Talks (<front>)

Wed 06 May 14:00: The uplift and erosion history of the Gamburtsev Subglacial Mountains and their role in the formation of the East Antarctic Ice Sheet

Departmental Talks - Tue, 07/04/2026 - 17:48

The uplift and erosion history of the Gamburtsev Subglacial Mountains and their role in the formation of the East Antarctic Ice Sheet

Valley networks in mountain ranges record the interactions between climate, tectonics, and geology. While drainage network analysis has transformed our understanding of these interactions in subaerial settings, the landscape evolution of ice-covered orogens is poorly known. The Gamburtsev Subglacial Mountains are a 600 km-long mountain range situated beneath the East Antarctic Ice Sheet, the largest ice sheet on Earth. These mountains are thought to have been an important nucleation site for the ice sheet approximately 34 million years ago and are now buried beneath 2 km of ice. Airborne geophysical surveying has revealed that the Gamburtsevs are characterised by a rugged, incised landscape, but their geological structure and uplift history remain enigmatic.

This talk will explore how radio-echo sounding (radar) data can be used to extract valley networks and longitudinal profiles from the Gamburtsevs. We combine analysis of these valley profiles with gravity and magnetic anomalies to infer details of the tectonic and geomorphic development of the mountains. For example, channel steepness indices and their relationship with magnetic anomalies allow us to confirm the positions of major geological boundaries that may date back to Gondwana assembly. Drainage basin analysis and stream power incision modelling are used to show that the morphology of the valley networks is largely consistent with fluvial incision that occurred prior to Eocene/Oligocene glaciation. This relic landscape is now preserved beneath the non-erosive centre of the East Antarctic Ice Sheet. Tectonic geomorphic analysis suggests that the routing of Gamburtsev fluvial systems was likely influenced by extensional faulting within East Antarctica, which may have controlled pre-glacial base level and the locations of interior sediment depocentres. We use these findings, together with independent estimates of denudation rates, to evaluate competing scenarios for the mechanism(s) and timing of Gamburtsev mountain uplift and valley incision. Finally, through numerical ice-sheet modelling, we examine how the uplift of these mountains may have played a crucial role in governing the nature and timing of the initial growth of the East Antarctic Ice Sheet.

Speaker: Guy Paxman (Durham)
Wednesday 06 May 2026, 14:00-15:00
Venue: Wolfson Lecture Theatre.
Series: Bullard Laboratories Wednesday Seminars; organiser: Alice Turner.

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Wed 01 Apr 14:00: Toward Foundation Models for Seismology and Geophysics

http://talks.cam.ac.uk/show/rss/15125 - Tue, 31/03/2026 - 13:49

Toward Foundation Models for Seismology and Geophysics

Deep learning has rapidly transformed seismology, and more generally geophysics, by shifting the focus from task-specific algorithms to learning general representations directly from data. Early successes came from supervised applications such as earthquake, as well as polyphonic seismo-volcanic signals detection upon introducing the “scattering network”, and phase picking but a key advance occurred with unsupervised (deep clustering) and self-supervised methods which we developed and that can organize seismic waveforms without reliance on labeled catalogs. These approaches uncover latent structure across multiple time scales and have enabled the discovery (and separation) of previously undetected events and subtle seismic phenomena. Building on these results, we introduced SeisLM, a large-scale pretrained (transformer-based) “foundation model”, trained on continuous global datasets to provide transferable representations that can be adapted across regions and tasks through fine tuning with minimal additional data, such as tremor detection associated with slow slip events. We show how self attention mechanisms naturally support forecasting, and introduce HARPA , a high-rate phase association framework that lifts arrival sequences associated with (unknown) microseismic events from arrays to probability distributions and compares them using an optimal transport metric; a generative travel time neural field is used to estimate the wave speed (and event locations) simultaneously with association. Leveraging an architecture reminiscent of cross attention encoding geometry, we further demonstrate that ray transforms – and implicitly the underlying wave speeds – can be learned directly from travel-time data. Finally, we present designs of foundation models, including Flowers, combining data-driven with physical principles, aimed at enabling scientific discovery. We show examples of approximating wave propagation and scattering, and fluid dynamics through data-driven surrogates.

Speaker: Maarten de Hoop (Rice University)
Wednesday 01 April 2026, 14:00-15:00
Venue: Wolfson Lecture Theatre.
Series: Bullard Laboratories Wednesday Seminars; organiser: Sergei Lebedev.

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Categories: Upcoming Talks (<front>)

Wed 01 Apr 14:00: Toward Foundation Models for Seismology and Geophysics

Departmental Talks - Tue, 31/03/2026 - 13:49

Toward Foundation Models for Seismology and Geophysics

Deep learning has rapidly transformed seismology, and more generally geophysics, by shifting the focus from task-specific algorithms to learning general representations directly from data. Early successes came from supervised applications such as earthquake, as well as polyphonic seismo-volcanic signals detection upon introducing the “scattering network”, and phase picking but a key advance occurred with unsupervised (deep clustering) and self-supervised methods which we developed and that can organize seismic waveforms without reliance on labeled catalogs. These approaches uncover latent structure across multiple time scales and have enabled the discovery (and separation) of previously undetected events and subtle seismic phenomena. Building on these results, we introduced SeisLM, a large-scale pretrained (transformer-based) “foundation model”, trained on continuous global datasets to provide transferable representations that can be adapted across regions and tasks through fine tuning with minimal additional data, such as tremor detection associated with slow slip events. We show how self attention mechanisms naturally support forecasting, and introduce HARPA , a high-rate phase association framework that lifts arrival sequences associated with (unknown) microseismic events from arrays to probability distributions and compares them using an optimal transport metric; a generative travel time neural field is used to estimate the wave speed (and event locations) simultaneously with association. Leveraging an architecture reminiscent of cross attention encoding geometry, we further demonstrate that ray transforms – and implicitly the underlying wave speeds – can be learned directly from travel-time data. Finally, we present designs of foundation models, including Flowers, combining data-driven with physical principles, aimed at enabling scientific discovery. We show examples of approximating wave propagation and scattering, and fluid dynamics through data-driven surrogates.

Speaker: Maarten de Hoop (Rice University)
Wednesday 01 April 2026, 14:00-15:00
Venue: Wolfson Lecture Theatre.
Series: Bullard Laboratories Wednesday Seminars; organiser: Sergei Lebedev.

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Wed 18 Mar 14:00: Magmatism and Faulting in Continental Rifts

http://talks.cam.ac.uk/show/rss/15125 - Tue, 17/03/2026 - 23:21

Magmatism and Faulting in Continental Rifts

The East African Rift System offers a unique opportunity to study the development of continental rifts, from amagmatic basins in the south to nascent seafloor spreading in the north. The canonical model is that continental extension initially forms a network of short fault segments, which gradually grow and link to form long border faults along pre-existing weak zones. As stretching continues, the lithosphere–asthenosphere boundary rises, and the volume of decompression melting increases. Magmatism and faulting become localised along magmatic segments within the basin. Ultimately, extension is dominated by dyke intrusions into very thin crust, resembling the processes of seafloor spreading. However, in reality, the continental lithosphere is highly heterogeneous, producing a diversity of tectonic and magmatic processes that do not always fit this simple story. In this talk, I will demonstrate how satellite observations are providing a fresh perspective on tectonic and magmatic processes at a continental scale, allowing us to target fieldwork to understand the active processes by which continental rifts form and the hazards they pose. I will show how using high resolution Digital Elevation Models has allowed us to map active fault scarps across the amagmatic Malawi Rift and what InSAR observations have revealed about magmatic activity within the mature continental rifts of Kenya and Ethiopia. Finally, I will discuss the crisis response and ongoing scientific investigation into the 2024-2025 Fentale-Dofen seismic-tectonic crisis, which was caused by the intrusion of a 50 km long dyke and triggered the evacuation of 75,000 people.

Speaker: Juliet Biggs (University of Bristol)
Wednesday 18 March 2026, 14:00-15:00
Venue: Wolfson Lecture Theatre.
Series: Bullard Laboratories Wednesday Seminars; organiser: Adriano Gualandi.

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Categories: Upcoming Talks (<front>)

Wed 18 Mar 14:00: Magmatism and Faulting in Continental Rifts

Departmental Talks - Tue, 17/03/2026 - 23:21

Magmatism and Faulting in Continental Rifts

The East African Rift System offers a unique opportunity to study the development of continental rifts, from amagmatic basins in the south to nascent seafloor spreading in the north. The canonical model is that continental extension initially forms a network of short fault segments, which gradually grow and link to form long border faults along pre-existing weak zones. As stretching continues, the lithosphere–asthenosphere boundary rises, and the volume of decompression melting increases. Magmatism and faulting become localised along magmatic segments within the basin. Ultimately, extension is dominated by dyke intrusions into very thin crust, resembling the processes of seafloor spreading. However, in reality, the continental lithosphere is highly heterogeneous, producing a diversity of tectonic and magmatic processes that do not always fit this simple story. In this talk, I will demonstrate how satellite observations are providing a fresh perspective on tectonic and magmatic processes at a continental scale, allowing us to target fieldwork to understand the active processes by which continental rifts form and the hazards they pose. I will show how using high resolution Digital Elevation Models has allowed us to map active fault scarps across the amagmatic Malawi Rift and what InSAR observations have revealed about magmatic activity within the mature continental rifts of Kenya and Ethiopia. Finally, I will discuss the crisis response and ongoing scientific investigation into the 2024-2025 Fentale-Dofen seismic-tectonic crisis, which was caused by the intrusion of a 50 km long dyke and triggered the evacuation of 75,000 people.