Jan. 30

Dr. Bayani Cardenas

Department of Earth and Planetary Sciences

Jackson School of Geosciences

University of Texas at Austin

Ridge to Reef Volcanic Hydrogeology: Submarine groundwater in the World’s Most Biodiverse Coasts

Abstract: Water flows from land to the ocean not only through rivers and estuaries but also below-ground through coastal and submarine aquifers. While the global fresh submarine groundwater discharge (SGD) is less than 1% of river discharge, it is quite relevant chemically as groundwater nutrient inputs are 25% of riverine inputs. This land-ocean connectivity is important for sensitive ecosystems such as coral reefs if the groundwater delivers solutes that are either critical for or harmful to reef life. Here, we present the interesting but potentially common situation of dramatic SGD in a volcanically active area in the Philippines which has been identified as the world’s most biodiverse coastal area and whose coral reefs provide for local communities.
We studied coastal and submarine thermal springs associated with high fluxes of acidic waters and carbon dioxide, some of which are within or close to thriving coral reefs. The SGD fluxes are amongst the largest in the world and the SGD carbon dioxide fluxes overwhelm coastal carbon budgets. The presentation delivers explanations for the high SGD, discussing the mechanics and different sources and pathways of water, by bringing together multiple lines of evidence from different methods including deep diving, drones, novel sensors, geochemical tracers, thermal remote sensing, and modeling.

Feb. 6

Dr. Peter DeCelles

University of Arizona

Why the Central Andes are Larger than the Himalaya

Abstract: The Central Andean and Himalayan orogenic belts provide an ideal natural experiment to test the potential role of climate in controlling orogeny. Approximately equal in age and along-strike length, both orogenic wedges are forming in plate-marginal convergent tectonic settings: The Andes in a retroarc setting and the Himalaya in a collisional setting against the Tibetan backstop. The Central Andes orogenic wedge is volumetrically and aerially nearly twice as large as the Himalayan orogenic wedge, despite the Himalaya having accommodated at least three times more tectonic shortening. The Himalaya exports at least four times more sediment owing to much greater erosion rates as signified by widespread Cenozoic metamorphic rocks and very young (<10 Ma) low-temperature thermochronologic ages. The Central Andes are thermochronologically old (mostly 20-100 Ma), have no exposures of Cenozoic metamorphic rocks, and are mantled by volcanic and sedimentary rocks, attesting to shallow, slow erosion. The most likely culprit for this situation is the greater intensity of the Indian Monsoon relative to the South American Monsoon since Oligocene time. When viewed as an orogenic wedge that has developed largely after formation of the Tibetan orogenic collage, the Himalaya is neither the largest nor hottest among Earth’s orogens.

Feb. 13

Dr. Yangkang Chen

Bureau of Economic Geology

Jackson School of Geosciences

University of Texas at Austin

AI for Seismology: How to Make it Work for Daily Operation and Better Science

Abstract: Artificial intelligence (AI) has witnessed enormous success in a variety of fields, especially in seismology. It has become widely accepted that deep learning (DL) techniques greatly help routine seismic monitoring by enabling more accurate P- and S-wave arrival picking than traditional methods. However, a completely automatic and in-production AI-driven earthquake monitoring framework has not been reported due to concerns about potential false positives using DL pickers. In this talk, I will introduce a novel AI-facilitated real-time earthquake monitoring framework developed from scratch over the past decade. The choice of optimal DL architecture is based on a decade-long iterative refinement of machine learning models and expansion of the training database. This AI system has been deployed in the Texas seismological network (TexNet) for daily operation. For the West Texas area, the seismic monitoring has been relying on our in-house DL model for reporting earthquakes to the public. For earthquakes with a magnitude above two, the picks are further validated by analysts to output the final TexNet catalog. Due to the fast-increasing seismicity caused by continuing oil & gas production in West Texas, this AI-facilitated framework significantly relieves the workload of TexNet analysts. On the other hand, AI techniques open the door to solving many scientific problems in an unprecedented way, including refining deep earth models with enhanced data preconditioning and iterative solvers, understanding the anthropogenic causes of induced earthquakes, and deciphering the earthquake nucleation mechanisms.

Feb. 20

Dr. Nicola Tisato

Department of Earth and Planetary Sciences

Jackson School of Geosciences

University of Texas at Austin

The Rock-Physics of Geo-Fluids

Abstract: The energy sector has long relied on subsurface exploration, with reservoir fluids playing a fundamental role in ensuring resources. Today, and likely in the future, exploiting the subsurface will be increasingly vital for advancing an energy landscape driven by emerging technologies that address the challenges of the climate crisis, such as geothermal, carbon capture utilization and sequestration (CCUS), and hydrogen storage. Therefore, enhancing our understanding of geologic processes by improving our geophysical toolkit is essential for implementing these innovations and boosting resilience. Here, I present scientific results that offer valuable insights for advancing subsurface imaging, monitoring, and exploration. I will showcase a combination of theoretical work with laboratory and numerical experiments investigating how multiphase fluids – e.g., CO₂ or hydrogen bubble-bearing brines – influence seismic wave propagation in reservoirs. I will also present novel rock physics experiments paired with micro-computed tomography (CT) imaging, revealing how the dissolution and precipitation of minerals in ultramafic rocks control their physical properties during carbon sequestration.

Feb. 27

Dr. Jean Philippe Avouac

California Institute of Technology

Advances in Earthquakes Forecasting

Abstract: Abundant and well documented examples of earthquakes induced by extracting or injecting fluids from the subsurface have provided an opportunity to investigate earthquake physics and test earthquake forecasting models. The presentation will show that spatial and temporal variations of seismicity rate can be predicted well based on stress changes informed by reservoir operations and surface deformation measurements. This modelling framework can be used to mitigate the risk of induced seismicity during CO2 storage of geothermal operations. These progress open avenues for time-dependent probabilistic forecasting of the time, location and magnitude of individual events.

March 6

Dr. Roger Creel

Department of Geology and Geophysics

Texas A&M University

Retreat, Regrowth, and Rapid Thinning: Reconstructing the Holocene History of the Antarctic Ice Sheet

Abstract: Understanding how the Antarctic Ice Sheet changed during past warm periods helps us project how fast Antarctica may shrink during the 21st century. The research I will present constrains Antarctic Ice Sheet change during the Holocene (11.7 – 0 thousand years ago), which is the last time global temperatures may have exceeded early Industrial (1850 CE) values. I will first estimate the Antarctic contribution to Holocene global mean sea level via a statistical framework that merges glacial isostatic adjustment models with observations of past sea level and nearfield Antarctic constraints. This estimate requires constructing the first quantitative estimates of Holocene mountain glacier volume and sea level change due to ocean thermal expansion, which I will discuss. I will then use cosmogenic nuclide exposure ages and marine sedimentary data to reconstruct how Antarctica thinned during the Holocene. I will close by comparing Antarctica’s Holocene history to modern and future trends to give perspective on the response of our largest ice sheet to warming.

March 13

Dr. Marjorie Cantine

College of Environment

Department of Earth and Space Sciences

University of Washington

Matters of Time: Controversy, Correlation, and the Dating of Sedimentary Records

Abstract: Time is a master variable in the Earth sciences, key to calculating rates and fluxes, drawing causal relationships between events, and determining the frequency of events. The importance of time motivates us to try and quantify it in sedimentary records of Earth’s changing life and environments. In this talk, I’ll discuss some of the geological and analytical challenges at the frontier of telling time in Earth’s complex surface environments and share the progress that my research group is making in dating the rise of animals on the Precambrian Earth.

March 27

Dr. Manuele Faccenda

Department of Geosciences

Università degli Studi di Padova, Padova, Italy

Central Mediterranean Structure and Dynamics From Combined Geodynamic and Seismological Modeling

Abstract: The Tertiary tectonic evolution of the Central Mediterranean and its first-order present-day structure have been relatively well constrained by abundant geological and geophysical data. Yet, several uncertainties persist about the mechanisms that led to the present-day surface morphology and deep slab geometry. With this respect, over the past few years new geodynamic and seismological modeling techniques have been combined to reproduce the recent large-scale evolution of the Central Mediterranean and provide mechanical constraints through the mapping of seismic anisotropy. The geodynamic simulations were designed and calibrated according to paleogeographic-tectonic reconstructions and seismological observations available in the literature. It is found that, although the opening of back-arc extensional basins in response to the retreat of the Ionian slab is a common feature in all models, structural heterogeneities within the Adria plate and/or the geometry of its Tyrrhenian passive margin profoundly impact on the segmentation of the subducting slab and the amount of Ionian trench retreat. This scenario is supported by anisotropic P-wave travel-time and S-wave splitting-intensity tomography models of the upper mantle covering the entire Mediterranean basin. The isotropic component of our preferred tomography model is dominated by numerous fast anomalies associated with retreating, stagnant, and detached slab segments. In contrast, relatively slower mantle structure is related to slab windows and the opening of back-arc basins. The anisotropy patterns are interpreted as the result of asthenospheric material flowing primarily horizontally around the main slabs in response to pressure exerted by their mid-to-late Cenozoic horizontal motion, while sub-vertical anisotropy possibly reflects asthenospheric entrainment by descending lithosphere.
The last part of the seminar is then dedicated to the discussion of a recent, stochastically-based, anisotropic tomographic model of the Etna volcanic field (Sicily, Italy), where a cylindrical pattern of P-wave slow axes is imaged in the 6-16 km depth range. According to the predictions of geodynamic modeling, this peculiar and unprecedently imaged structure should be primarily related to a radially distributed vertical dikes departing from a pressurized magma chamber.

April 3

Dr. Zhe Jia

University of Texas Institute for Geophysics

Jackson School of Geosciences

Earthquake Source Complexities: Insights on Rupture Dynamics and Hazard Mitigation

Abstract: Effectively assessing and reducing earthquake risks requires understanding why earthquakes can unfold in ways that standard seismic models often fail to predict. This talk explores how fault ruptures can be more complex than our usual assumptions suggest, making earthquake magnitudes and impacts especially hard to forecast. In this talk, I highlight some representative major earthquakes in recent years to illustrate the complexity of seismic ruptures. By integrating new modeling methods with multiple geophysical data and lenses, we can quantify their detailed rupture complexities, examine the compositional and thermal conditions of their source regions, and dynamically reproduce their faulting processes to uncover underlying physics and controlling factors. These advances provide insights into Earth’s multi-scale dynamics and highlight the value of unifying views from data-driven and physics-based models. By systematically exploring rupture complexities, we take steps toward closing the gap between theoretical and observational understanding of earthquake physics, thereby improving earthquake forecasts and hazard mitigation.

April 17

Dr. Charlie Kerans

Department of Earth and Planetary Sciences

Jackson School of Geosciences

University of Texas at Austin

Sea Level and Climate Patterns During the Last Interglacial for the Bahamas-Caicos Archipelago: Impact of a 40 yr Program of Carbonate Field Research

Abstract: Carbonate strata host a rich record of paleoclimate and past sea level during the Last Interglacial (LIG) across the Bahamas-Caicos Archipelago (BCA). Current models of ice sheet history and glacioisostatic adjustment across the LIG can be significantly improved by a detailed whole-island/cross-archipelago understanding of this record. Field data from Great Inagua, the Caicos Platform, San Salvador Island, and Abaco are leveraged here with cross-BCA DEM data and airborne lidar imagery to provide new estimates of relative sea level (RSL). Essential improvements in GIA models and global mean sea level (GMSL) estimates can derive from these data. However, the myopic focus on GMSL may be, in part, a distraction from the insights gained into past climate states and wave/wind energy in the western North Atlantic during the LIG vs. the mid-late Holocene.

Before covering the BCA story, a vignette of the JSG carbonate group’s path to arrive at this focus on Pleistocene RSL and paleoclimate will emphasize the importance of field-based research and education in reaching these insights. The BEG Reservoir Characterization Research Lab began detailed characterization of carbonate outcrops and subsurface datasets in 1987 and has continued pushing science and technological boundaries in outcrop digital characterization and stratigraphic analysis. The Permian Basin, the Cretaceous and Jurassic of the GOM and Middle East, and most recently the Holocene-Pleistocene of the BCA have been significant “testing grounds” for this research. Much of this work has enhanced our field educational curriculum and been improved by it.

This combined expertise in carbonate outcrop characterization has enabled interrogation of Pleistocene stratigraphy across the BCA in a way not previously possible, allowing a more complete reconstruction of the archipelago’s dynamic relative sea level history. The BCA MIS 5e RSL record is shown to include an early +4 m highstand, followed by a short-lived fall to +1m, and then a peak highstand of at least +6, but more likely +8-10 m, before a rapid forced regression dropped SL below the top of the platforms. The previous suggestion of a northward gradual increase in peak MIS 5e RSL from 2.2 m in the southwest to above 6.5 m in the north is challenged, suggesting a need for reassessment of recent GIA models. The dramatically more energetic aeolian and wave-generated deposits of the MIS 5e could be of equal or greater importance relative to GMSL in assessing climate impacts of a warmer world as compared to their mid-late Holocene counterparts.

April 24

Dr. Karen McKinnon

University of California Los Angeles

Another record-breaking heatwave? Understanding the trends and drivers of heat extremes

Abstract: Heat extremes result from the convergence of atmospheric and land processes across multiple spatial and temporal scales. While we can be quite confident that heat extremes will become more frequent in a warming world, major uncertainties remain in terms of how and why they will change. A recent notable example was the 2021 Pacific Northwest heatwave, which was so extreme that researchers initially struggled to put a nonzero probability on it. Using both in situ observations and a large climate model (CESM2) ensemble, we find that record-smashing extremes are much more likely to occur in regions like the Pacific Northwest that have climatologically positively skewed temperatures, which reflect the existence of processes that converge to cause very large extremes. As a result, the event was consistent with a human-caused warming of the mean combined with a low-probability sampling of an extreme weather pattern. More broadly, do we find evidence in the observational record that summertime extremes are warming faster than typical summertime temperatures? Despite the many recent high-impact heat waves around the world, we find that observations and climate models agree that the hottest summer temperatures have warmed at the same pace as the median from 1959-2023, although the coldest summer temperatures have warmed more slowly. The trends in the extremes compared to the median can be predicted from an equation derived from the surface energy balance, and are due to changes in surface radiative heating, and the fraction of heat that goes into evaporating water, on extreme versus typical days. Finally, we show that, in contrast to the general expectation of humidity increasing in a warmer climate, humidity has been decreasing on hot days across the semiarid subtropics, with concerning implications for fire risk. In the US Southwest, we trace the decrease to declining soil moisture and evapotranspiration, indicating an important land surface control on humidity trends. Collectively, the results provide a framework for understanding the probability of very unusual events in the relatively short observational record, and highlight the important role of energy partitioning at the surface for both heat and humidity trends.