Events

First Day of Classes

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Faculty Meeting

UTIG Seminar Series: Luke Zoet, University of Wisconsin-Madison

Speaker: Luke Zoet, Associate Professor, Department of Geosciences, University of Wisconsin- Madison

Host: Ginny Catania

Title: Determining how glaciers deform their beds

Abstract: Many fast-moving glaciers move atop beds made of deformable sediments (till), and deformation of these subglacial sediments during basal slip shapes the beds and regulates glacier flow. The resultant sediment flux impacts glacier dynamics and rates of subglacial erosion over a range of timescales, but its fundamental dependencies are not well understood. Using a cryogenic ring shear device, we conducted experiments to investigate the effects of both effective stress and slip speed on rates of till transport. We find a near-linear relationship between sediment flux and slip speed, but a non-monotonic, double-valued dependency of sediment flux on effective stress. Deformation primarily occurred in a thin shear band near the ice sole, the thickness of which could vary with both parameters.

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Faculty Meeting

DeFord Lecture | Alicia Wilson

Subseafloor Hydrogeology: Moving Beyond Watersheds by Alicia Wilson, University of South Carolina

Abstract: The field of submarine groundwater discharge (SGD) was launched in the 1990s by the remarkable discovery, via naturally-occurring isotopic tracers, that saline groundwater was discharging to the South Atlantic Bight in very large volumes. Subsequent studies confirmed that saline groundwater discharges to the Atlantic Ocean in volumes that rival river discharge. All available evidence indicates that this saline groundwater is highly enriched in nutrients compared to river water, so the nutrient contributions of this submarine discharge exceed that of river discharge. These findings have been slow to find widespread acceptance, however, because it has been exceedingly difficult to confirm this flow by means other than the original isotropic tracers. This discharge does not occur near the shoreline, and no conceptual models for SGD far from shore existed.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating DGS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Ignacio Sepulveda, San Diego State University

Speaker: Ignacio Sepulveda, Assistant Professor, Coastal Engineering, San Diego State University

Host: Harm van Avendonk

Title: Compound and cascading processes shaping tsunami responses: A new era of multidisciplinary research

Abstract: Catastrophic tsunamis in the last few years have evidenced a more complex genesis and coastal response than previously thought. As a consequence, tsunami modeling and hazard prediction tools are under scrutiny. New tsunami research is needed which shall integrate multiple disciplines. Two pressing questions investigated by our group are the influence of compounding processes increasing tsunami hazard and the understanding of non-conventional geophysical processes cascading into tsunamis.
Tides and climate driven sea level rise (SLR) contribute significantly to water level changes in the short and long term, respectively. In terms of magnitude, they could be comparable to tsunamis of interest at certain coasts. New non-stationary probabilistic tsunami hazard assessment (nPTHA) methods are developed to include the mean sea level changes due to a warming climate and the uncertainty of the tidal phase at the moment of tsunami occurrence. A surrogate model is used in the nPTHA method to render the calculation feasible and efficient. The development of formulations based on surrogate models is the key to establishing a method which feasibly can be applied to other regions for comprehensive analysis at a global scale. As an illustration, these methods are applied for assessing tsunamis generated in the Manila Subduction Zone and impacting the coasts of Kao Hsiung and Hong Kong. The results of the illustration case show that tides have a relevant impact on the nPTHA. However, the SLR within an exposure time of 100 years has a stronger impact. It is perhaps counterintuitive for the increase in hazard from SLR to be greater than the increase from tides, when the perception by the general public may be that tides are much bigger than estimates of SLR, because of familiarity. This poses an outreach opportunity for increasing awareness of climate change and tsunami hazards.

Recent catastrophic tsunamis have also evidenced the relevance of non-conventional tsunamigenic sources. The 2022 Hunga Tonga-Hunga Ha’apai Volcano eruption, in particular, triggered a tsunami which was recorded globally. While the highest tsunami crest-to-trough heights, up to 3 meters, were only recorded within the Pacific coastlines, heights up to 1 meter could be also observed in remote locations such as Ghana and Portugal. The high waves and far-reaching character of the tsunami reopened the question about the destructive potential of volcanic tsunami hazards. The signature of the 2022 tsunami around the globe is investigated and new numerical tools to simulate the special forcing mechanisms of volcanic sources are under development. These studies aim to provide tools for volcanic tsunami hazard assessment approaches and to improve the quantification of their uncertainties.

CPSH Seminar Series: Sean Gulick, CPSH & UTIG

Speaker: Sean Gulick, Co-Director, UT Center for Planetary Systems Habitability, Research Professor, University of Texas Institute for Geophysics, Jackson School of Geosciences

Host: Brandon Jones

Title: Beyond Mass Extinction: Hydrothermal Habitats at the Chicxulub and Ries Impact Structures

Location: PMA 15.216B, Physics, Math and Astronomy Bldg.
UT Austin, Department of Astronomy
2515 Speedway, Stop C1400
Austin, Texas 78712-1205

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DeFord Lecture | Ekaterina Larina

Paleoenvironmental and paleoecological trends leading up to the end-Triassic mass extinction by Ekaterina (Katya) Larina, Jackson School of Geosciences

Abstract: The end-Triassic mass extinction (ETE) is one of the biggest biotic crises that has occurred during geological history and the main cause is generally attributed to the emplacement of the Central Atlantic Magmatic Province (CAMP) ~201.51 million years ago. The amount of CO2 injected into the atmosphere during each CAMP magmatic pulse rivals anthropogenic CO2 emission projected for the 21st century. Although the ETE and its aftermath are well documented, the conditions leading up to the ETE remain poorly understood. This study aims to resolve environmental conditions in Panthalassic and Tethys basins that acted in the leadup to the ETE and its impact on the complexity of marine benthic ecosystems. The study of upper Rhaetian sections in Tethys realm reveals an ecologically diverse and robust marine benthic community across different depositional environments all the way up to the main phase of CAMP volcanism implying the sudden tempo of ecological changes in Tethys compared to the more protracted nature of ecological shifts recorded in the Panthalassa. Despite disparities in paleoenvironmental and paleoecological trends in the lead up to the ETE across the basins, the severity of the extinction is apparent across the globe once the main phase of CAMP volcanic activity was initiated.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating DGS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

RoKafe