Events

DeFord Lecture: Melissa Kemp

Biodiversity in the Anthropocene: a paleobiological perspective

About Dr. Melissa Kemp (UT Austin)
Impact of Sea level change and colonization on Caribbean lizards; how extinction, diversification, and colonization are shaped by environmental perturbations; integration of macroevolutionary theory with paleobiology, ecology, and conservation biology by combining field, laboratory, and quantitative methods.

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: William Frank, MIT

Speaker: William Frank, Massachusetts Institute of Technology

Host: Demian Saffer

Title: The transient and intermittent nature of slow slip

Abstract: Slow, aseismic slip (such as slow slip and surface creep) is now recognized as the glue at tectonic plate boundaries that holds the earthquake cycle together. Since the first observations of surface creep along the San Andreas plate boundary more than 50 years ago, advances in geophysical instrumentation and innovative observational approaches have revealed that faulting at major plate boundaries covers a broad spectrum of slip modes, from fast earthquake ruptures to intermittent slow slip.

Today, the continuous GPS record and satellite imagery reveal the jerky, intermittent nature of aseismic slip. The pattern that is emerging suggests that slow slip at plate boundaries and surface creep on major transform faults is not a steady, continuous process as once thought, but is rather a complex spatiotemporal cluster of interacting aseismic transients. Aseismic slip rate variations have now been observed at all temporal scales, from seconds to decades. These new observations suggest slow slip is much more similar to earthquake slip than previously acknowledged, with strong implications on our understanding of the dynamics of active faults. These new observations call for new families of models with much broader dynamics that are able to reproduce the observed rich spectrum of slow slip.

Habitability Seminar: Eric Anslyn, University of Texas at Austin

A seminar from the Center for Planetary Systems Habitability

Title: Information Storage in Abiotic Sequence-Defined Polymers – Their Potential for Replication and in Seeking Molecular Complexity

Speaker: Eric Anslyn, Professor, Department of Chemistry, College of Natural Sciences, University of Texas at Austin

https://habitability.utexas.edu/events/

DeFord Lecture: Jennifer McIntosh

Evolution of Earth’s Deep Terrestrial Water Cycle over Geological Timescales

About Dr. Jennifer McIntosh (University of Arizona)
Hydrogeochemist who works at the interface of hydrology, geochemistry, and microbiology to understand micro (pore) to macro (continental scale) processes throughout the earth’s crust. Regional hydrogeologic phenomena and geofluids. Reactive transport.

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: Emily Eidam, UNC at Chapel Hill

Speaker: Emily Eidam, University of North Carolina at Chapel Hill

Host: John Goff

Title: Changes in hydrodynamics and sediment dynamics of the Coos Bay Estuary related to 150 years of modifications

Abstract: Estuaries worldwide have experienced modifications including channel deepening and intertidal reclamation over several centuries, resulting in altered hydrodynamics and fine sediment routing. The Coos Bay Estuary in Oregon, the largest west-coast estuary between San Francisco Bay and the Columbia River mouth, has been extensively modified since the 1860s. We used a coupled hydrodynamic and sediment transport model to evaluate changes in estuarine dynamics between 1865 (using a grid based on digitized historic survey charts) and present (using a compilation of new high-resolution bathymetry data).  Dredging and other development projects have led to an increase in channel depth from ~6.7 to 11 m, a 12% increase in area, and a 21% increase in volume. These changes are associated with a 33% increase in tidal amplitude, an 18% increase in salinity intrusion length, and a doubling of the subtidal salt flux. These changes have reduced current magnitudes, reduced bed stresses, and increased stratification, especially during rainy periods. River water and sediment effluent from the Coos River have been re-routed from broad intertidal flats to a dredged navigation channel, where an estuarine turbidity maximum (ETM) forms. This “new” ETM supplies sediment to proximal embayments in the middle estuary and the shallow flats. Overall, sediment trapping during winter (and high river discharges) has increased more than two-fold, owing to increased accommodation space, altered pathways of supply, and altered bed stresses and tidal asymmetries. In contrast to funnel-shaped estuaries with simpler geometries and river-channel transitions, these results highlight the importance of channel routing and dredging to sediment routing and retention.