Fall 2020

Fridays at 12:00 PM

Zoom information can be found on the EPS advising Google calendar

October 9, 2020

Speaker: Saman Karimi, Johns Hopkins University

Title: Why Are There Numerous Mascons on the Moon, But Not Elsewhere


October 16, 2020

Speaker: Jessica Velasquez, Risk Management Solutions (RMS)

Title: Less is not more: Earthquake source modeling case studies for risk uncertainties

Abstract: How do we constrain the unconstrained? How do we say something about a region where we just don’t have the data? That’s when we have to gather together all of the available information to try to string together a coherent story and an understanding of its uncertainties. It’s where your work comes into play, whether you intended it for our use case or not. Here we’ll look at two case studies: (1) Taking a look at the uncertainties, discrepancies, and data scarcity with respect to the Southern Middle American Subduction Zone. (2) Highlighting the importance of faults in risk and the impact of their uncertainties with respect to Taiwan and Ecuador.

October 23, 2020

Speaker: Laura Wallace, GNS Science, New Zealand, and the University of Texas Insitute for Geophysics

Title: Relationships between slow slip events, megathrust locking, and seismicity at the HIkurangi subduction zone, New Zealand


October 30, 2020

Speaker: Samer Naif, Georgia Institute of Technology

Title:Imaging fluid-rich faults and melt-rich asthenosphere with electromagnetic data: Examples from the Hikurangi and Middle America subduction margins

Abstract: Fluids and partial melts are critical factors in several plate tectonic processes. In this presentation, I will briefly review the utility of electromagnetic (EM) methods and discuss two research applications: (1) what the distribution of fluids tell us about shallow plate coupling and slip behavior at subduction zones, and (2) on the origin of the lithosphere-asthenosphere boundary (LAB). The first application will feature results from marine EM surveys at the Central America subduction margin offshore Nicaragua and the Hikurangi subduction margin offshore North Island, New Zealand. For the second application, I will show the synthesis of several geophysical and geochemical data sets from the Cocos plate––including work done in the region by UCSC researchers Brian Dreyer, Andy Fisher, and Eli Silver––to explain the origin of a partial melt channel previously inferred at the LAB.


November 6, 2020

Speaker: Lujendra Ojha, Rutgers University

Title: Can an Early Hot Mars Resolve the Faint Young Sun Paradox?

Abstract: In explaining extensive evidence for past liquid water, the debate on whether Mars was primarily warm and wet or cold and arid 4-Ga ago has continued for decades. The Sun’s luminosity was ~30% lower 4-Ga ago; thus, most Martian climate models struggle to elevate the mean annual surface temperature past the melting point of water. Geothermal basal melting of thick ice sheets may help resolve that paradox. In this work, we model the thermophysical evolution of ice and estimate the geothermal heat flux required to produce meltwater on a cold, arid Mars. We then analyze geophysical and geochemical data, showing that basal melting would have been feasible on Mars 4-Ga ago. Alternatively, if Mars were warm and wet 4-Ga ago, the geothermal flux would have even sustained hydrothermal activity. Accordingly, regardless of the actual nature of the ancient Martian climate, the deep subsurface could have been the most habitable region on Mars.


November 13, 2020

Speaker: Sabine Stanley, Johns Hopkins University

Title: Saturn’s Enigmatic Dynamo


November 20, 2020

Speaker: Quentin Nenon, UC Berkeley

Title: The radiation belts of Jupiter and their interplay with Io and Europa


Abstract: The radiation belts of Jupiter are populated by energetic charged particles (electrons, ions) trapped by the gigantic magnetic field of the planet. The distribution and fluxes of these particles are sculpted by their interaction with the inner magnetosphere environment, including the environments induced by the volcanic moon Io and the icy Europa: surfaces, exospheres, extended neutral torii, cold plasma and electromagnetic waves. Conversely, the radiation belts of Jupiter are important to understand the weathering of Europa’s surface and the possible preservation of biosignatures. This seminar will give an overview on recent advances regarding the interlink between the Jovian radiation belts and the Io-Europa system. To do so, simulations conducted with a global physics-based model of the radiation belts will be contrasted with in-situ particle measurements by Pioneer 10-11, Voyager 1, Galileo and Juno. Remaining secrets that can be unlocked by a mission dedicated to the radiation belts of Jupiter will be presented, as their relevance to space physics and planetary science.

December 4, 2020

Speaker: Sarah Titus, Carleton College

Title: Unraveling the history of the San Andreas fault system in central California


December 11, 2020

AGU Annual Meeting