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GPS Event Calendar

Online Seminars & Events

Week of November 23, 2020
GPS Division Seminar
12:00 pm to 1:00 pm
DIX Planetary Science Seminar
4:00 pm to 5:00 pm
Thanksgiving (Institute holiday) Thanksgiving (Institute holiday)

Division Seminar

Mondays from 12:00pm to 1:00pm
For more information, please contact: Leticia Calderon

" Paleomagnetic Insights into Impact Cratering Processes "

Sonia Tikoo, Stanford University


Impact cratering is arguably the most ubiquitous modifier of planetary surfaces across the solar system. Impacts expose rocks to powerful shock waves and heat, and can generate long-lived hydrothermal systems. These three impact effects can produce different forms of remanent magnetization that are preserved within craters. Here we discuss how paleomagnetism is being used to elucidate the formation of impact structures, the origin of magnetic anomalies, the nature and duration of post-impact hydrothermal activity, and the effects of shock and heating on target rocks at the 200-km diameter Chicxulub crater, Mexico.

Brief Bio:

Sonia Tikoo is an Assistant Professor of Geophysics and, by courtesy, Geological Sciences at Stanford University. Her research interests are in the application of paleomagnetism to problems in the planetary sciences. Tikoo earned a B.S. degree in Geology and History (Minor) from Caltech in 2008 and. Ph.D. in Planetary Sciences from MIT in 2014.

"Summertime ozone in North America: Isolating weather-driven ozone pollution events and evaluating trends in precursor emissions"

Dylan Jones, University of Toronto


Air pollution regulations have led to dramatic reductions in emissions of air quality pollutants in North America, and thus improvements in air quality, during the past three decades. However, ozone pollution episodes remain an issue in some regions of North America. Furthermore, there are uncertainties in the trend in emissions of nitrogen oxides (NOx), a key ozone precursor. In this talk I will examine the link between summertime ozone pollution episodes and large-scale atmospheric circulation patterns and present an analysis isolating the weather-driven component of ozone pollution episodes. I will also review the discrepancies in recent trends of emissions of NOx in the United States and discuss the use of a deep learning model to evaluate the consistency of the reported trends in NOx emissions with observations of surface ozone.


Mark Torres, Rice University


Claudio Faccenna, University of Texas at Austin


Ilse Cleeves, University of Virginia


Stephen Grand, University of Texas at Austin


Ashley Shade, Michigan State University


Caroline Morley, University of Texas at Austin

DIX Planetary Science Seminar

Tuesdays at 4:00 pm
For more information, please contact Aida Behmard

"The Volatile Composition of Comets"

S. Faggi, NASA

Abstract: The importance of studying water and organic molecules in comets is related to their biological relevance. The origin of water oceans and pre-biotic organic molecules on Earth is still unsolved. The terrestrial planets formed in a dry region of the proto-planetary disk by aggregation of rocky planetesimals; icy aggregates could form only beyond the frost lines. Even today the bulk Earth is cosmically dry (poor in H, relative to the protoplanetary disk). About 60 Ma after Earth-accretion, the moon-forming impact probably removed any water that may have outgassed after core formation, leaving the Hadean Earth probably water-poor at its surface. How did Earth acquire its water?

Bombardments of Earth and inner planets by icy and rocky planetesimals (represented today by comet nuclei and asteroids) were common from their formation through the Late Heavy Bombardment. Because water is the most abundant native ice in cometary nuclei, with the aggregate CHON ices comprising a close second, we want to understand the role primitive bodies played in delivering water and pre-biotic organics to the young inner planets.

High resolution spectroscopy with long-slit echelle spectrometers is powerful method for ground- based IR surveys. In the infrared spectral region of about (3 – 5 um), trace volatiles are sampled simultaneously with H2O. The inter-comparison of cosmogonic indicators in comets and in planetary atmospheres through high-resolution spectroscopic studies might address these unresolved questions.

Environmental Science and Engineering Seminar

Wednesdays from 4:00pm to 5:00pm
For more information, please contact: Bronagh Glaser

"Role of Long-Duration Energy Storage in Variable Renewable Electricity Systems"

Jackie Dowling, Caltech Krystal Vasquez, Caltech

Abstract: Reliable and affordable electricity systems based on variable energy sources, such as wind and solar may depend on the ability to store large quantities of low-cost energy over long timescales. Here, we use 39 years of hourly U.S. weather data, and a macro-scale energy model to evaluate capacities and dispatch in least cost, 100% reliable electricity systems with wind and solar generation supported by long-duration storage (LDS; 10 h or greater) and battery storage. We find that the introduction of LDS lowers total system costs relative to wind-solar-battery systems, and that system costs are twice as sensitive to reductions in LDS costs as to reductions in battery costs. In least-cost systems, batteries are used primarily for intra-day storage and LDS is used primarily for inter-season and multi-year storage. Moreover, dependence on LDS increases when the system is optimized over more years. LDS technologies could improve the affordability of renewable electricity.

Geoclub Seminar Series

Thursdays from 4:00pm to 5:00pm
For more information, please contact: Sarah Zeichner

"Clinopyroxene geothermometry & diffusion chronometry of the Scaup Lake rhyolite, Yellowstone"

Kara Brugman, Postdoctoral Fellow, Arizona State University/Carnegie


Volcanic eruptions are serious geological hazards; the aftermath of the explosive eruptions produced at high-silica volcanic systems often results in long-term threats to climate, travel, farming, and human life. One of these systems, Yellowstone caldera, is the site of some of the largest explosive eruptions in history, which blanketed much of North America in ash and produced erupted volumes 1120–9800 times that of the 1980 Mount St. Helens eruption. In order to construct models for eruption forecasting, the timescales of events leading up to eruption must be accurately quantified. In the field of igneous petrology, the timing of these events (e.g., periods of magma formation, duration of recharge events) and their influence on eruptive timescales are still poorly constrained.

In this talk I will discuss how the new tools and methods I have developed are helping to improve our understanding of these magmatic events. I use my new diffusion chronometry technique to compare the timescales recorded by different minerals from the same Yellowstone lava flow, the Scaup Lake rhyolite. My new geothermometer for high-silica system clinopyroxene lowers calculated temperatures by an average of over 80°C relative to prior assessments and improves error by more than half. Together, these tools allow us to paint a more accurate picture of the conditions and tempo of events inside a magma body in the millennia to months leading up to eruption.

Seismo Lab Seminar

Fridays from 4:00 pm to 5:00 pm
For more information, please contact Seismo Seminar Committee.


Dr. Melissa Sims, John Hopkins University

Thesis Defense Seminars

For more information, please contact Julie Lee; jlee@gps.caltech.edu