GPS Event Calendar

" Using Microseismicity to Track Deformation in Salt Dome Storage "
Patricia Persaud - Louisiana State University
via Zoom 12:00 PM (Pacific Time)

Bio

Persaud is an assistant professor of Geophysics at Louisiana State University. She graduated from the University of Houston with a BS in Geophysics and holds a PhD in Geophysics from California Institute of Technology. She was a Postdoctoral Science Fellow at the Lamont-Doherty Earth Observatory of Columbia University. She is a 2020-21 fellow of the Radcliffe Institute for Advanced Study at Harvard University. Her research focuses on seismic imaging with large arrays, and monitoring deformation at volcanos and underground storage caverns. Her group also uses deep ocean drilling and oil industry borehole data to constrain the stress field.

Abstract

Underground caverns in salt formations are used to store industrial waste and fuel, such as natural gas and hydrogen. The Gulf Coast plays an important role in the energy security of the US. This region has several massive underground caverns including the four US Strategic Petroleum Reserve sites that are used to increase energy supplies during emergency shortages such as hurricanes. Salt caverns are subject to substantial modifications and are affected by loading and unloading. Unstable caverns pose a hazard to nearby communities because they can collapse, leading to sinkhole formation and the release of gas. In this talk, I will present results from a study to investigate deformation of the Sorrento salt dome in Louisiana using seismic arrays that started recording in early 2020. Results include the detection of a seismicity spike in the days preceding a well failure. I will also discuss implications for the monitoring of long-term CO2 storage sites.

" Interpreting triple-oxygen isotope compositions in the geologic sulfur cycle "
Jordon D. Hemingway, Eidgenössische Technische Hochschule (ETH) Zürich

"Reconstructing Depositional and Diagenetic Conditions from Bulk and Microscale Sedimentary Sulfur Isotope Records"
David Fike, Washington University
Abstract: Stable isotopic data (e.g., d13C or d34S) provide a framework for understanding biogeochemical cycling today and for reconstructing both global redox budgets and environmental change over Earth history. These reconstructions often rely on bulk sediment measurements and the assumption that the values measured at a given stratigraphic section provide information about global biogeochemistry. Here we demonstrate that d34S signatures that span a range of > 70‰ in marine sedimentary pyrites are controlled by variations in ambient depositional conditions, particularly sedimentation rate, organic carbon loading, and iron availability. Grain-specific isotope analysis by secondary ion mass spectrometry (SIMS) reveals that this isotopic sensitivity primarily results from how these depositional conditions modulate pyrite formation in the sediment column, rather than variations in the inherent isotopic fractionation by sulfur cycling metabolisms. Moreover, these results demonstrate that we can reconstruct original biological fractionation and resolve the relative order of pyrite formation within a sediment, extracting additional information about the evolving porewater environment. We show that local depositional variations in modern systems give rise to stratigraphically coherent d34S trends that are not representative of global S cycling. This requires that we revisit the interpretation of pyrite d34S records preserved in ancient strata.

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Marianne Walck – The James R. and Shirley A. Kliegel Lecture in Geological and Planetary Sciences, Idaho National Laboratory

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Terry Plank, Lamont Doherty Earth Observatory, Columbia University

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Matt Clement, Carnegie Institute of Washington

"Fresh ways to observe evolving exoplanet atmospheres"

Jess Spake, Postdoctoral Scholar Research Associate, Planetary Sciences, California Institute of Technology
Abstract: I'm interested in developing new methods to observe exoplanet atmospheres, and test their use in answering questions that are difficult to answer more directly. For example, what is the mass-loss history for a given planet? How strong is its magnetic field? How has its interior temperature evolved over time? For most of the talk I'll be discussing atmospheric escape, which is a vital process in planetary evolution. I'll present the potential new atmospheric physics we can learn with observations of helium in escaping atmospheres. I'll also briefly share an upcoming project in which we will use observations of exoplanet atmospheres with the James Webb Space Telescope to try and constrain the evolution of planetary interiors.

"Chasing Asteroids in the Infrared: NEOWISE and NEO Surveyor"

Joe Maisero, Research Scientist, IPAC, California Institute of Technology
Abstract: Thermal infrared observations are an ideal tool for studying the small bodies of the Solar system. Not only are asteroids some of the brightest objects in the sky at thermal wavelengths, but measurements of their brightness allow us to directly constrain their sizes. These capabilities allowed the NEOWISE mission, during its seven month cryogenic phase, to discover over 30,000 new objects and measure sizes and albedos for over 130,000 asteroids. I will highlight some of the results of the original NEOWISE survey, discuss its continued output during the post-cryo Reactivation mission, and describe how we are taking the lessons learned from NEOWISE to design the next generation asteroid survey mission: NEO Surveyor.

"Field Courses for All: Creating inclusive field learning opportunities for students and faculty with disabilities"
Anita Marshall, University of Florida, Gainesville
Abstract: In the geosciences, field work is valued for learning opportunities and research, as well as personal and professional growth for students. But exclusion from these formative learning experiences can negatively influence degree persistence and career prospects for students with disabilities. Based on an evaluation of disability-inclusive field courses, current work designing an accessible field course, and personal experiences undertaking field research with a physical disability, this presentation will explore a technology-based approach to inclusive field learning and best practices for building supportive learning communities that can be applied in any setting; classroom, lab, field, or virtual.

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Katrina Hui, Graduate Student, Environmental Science and Engineering, Caltech

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Elizabeth Barnes, Colorado State University

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Alberto Naveira Garabato, University of Southampton

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Brian Arbic, University of Michigan

" Exploring Mammals of L.A.'s Urban Core: A Community Effort "
Miguel Ordenana, Natural History Museum of LA County
Abstract:

The false narrative that cities are devoid of nature can have long lasting negative impacts on the relationships between individuals and nature, including my own. Fortunately, inspiring narratives have emerged from local urban biodiversity research and community science projects that make urban nature both more visible and relevant to LA area communities. Projects like the Backyard Bat Survey have made some unexpected species detections in extremely urban areas due to the incorporation of community science, innovative technology, and accessible species into the study design. The results of our projects support the idea that urban wildlife research can not be done comprehensively or equitably without authentically embedding community engagement into a project's design. The NHMLA community science program aims to create more equitable partnerships with historically excluded communities through co-created projects and community driven projects.

"Washload or bed sediment entrainment? Constraining deltaic mud deposition and transport dynamics with field measurements, remote-sensing, and numerical modeling"
Gerard Salter, Postdoctoral Scholar, Caltech

Abstract:

Most of the sediment carried by rivers is composed of mud, but the dynamics of mud transport remain poorly understood. Mud in rivers is commonly assumed to constitute washload, which by definition does not interact significantly with the bed and is controlled by sediment supply from upstream. However, a growing body of research indicates that mud is flocculated and undergoes active exchange with the riverbed even in freshwater. Mud transport is particularly important in river deltas, where the balance between sediment deposition and relative sea level rise is a critical control on whether a delta builds/maintains land or drowns. In this talk, I present a case study on mud transport and accretion in Wax Lake Delta, Louisiana, an actively growing sub-delta of the Mississippi River. First, I present a novel method for inferring instantaneous sedimentation rates from remote-sensed sediment concentrations. Patterns of deposition and erosion suggest that mud is actively exchanged between the flow and the bed. Next, our in-situ field measurements provide additional support for flocculated mud transport in Wax Lake Delta. Finally, I use numerical modeling to explore the implications of flocculation for predicting mud concentrations and accretion across the delta. Comparison of model results to remote-sensed data highlight the importance of active exchange of mud between the flow and the bed. Future work will build on these results to predict the vulnerability of different parts of the Mississippi River Delta to land loss.

" Perspectives on polyphonic signal identification, classification, source localization and geophysical forecasting with deep learning "
Maarten V. de Hoop - RICE University
ABSTRACT:

We present a collection of deep neural networks designed to perform various tasks in seismology. These include polyphonic signal detection, identification, clustering, classification and segmentation, unsupervised and supervised, and forecasting on continuous seismic data. We introduce deep consensus providing a framework for regional source localization and wave speed recovery using arrays. Concerning forecasting, we discuss two-stage approaches learning spatio-temporal conditional densities through flows and time-to-failure using the attention mechanism. Causal inference provides a framework for further characterization of signal clusters using, for example, GPS data. While the networks' designs are rooted in a mathematical understanding of deep learning, we emphasize, here, applications including the anatomy of Mars SEIS data.

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Wei Wang USC

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Seogi Kang, Stanford

"Radiation-based analytic approaches to investigate the Earth's atmosphere"

Members of the Ph.D. examining committee are: Paul Wennberg (chair), Yuk Yung (thesis advisor), Tapio Schneider, Christian Frankenberg