Category: Seminars

Speaker:
Britney Schmidt
University of Texas

Abstract:
With an icy exterior covering a global ocean, Europa has long been a target of interest in the search for life beyond Earth. Europa exists in a dynamic environment, subject to intense irradiation and impact as well as immense tides from Jupiter. These processes deliver important thermal and chemical energy that could be critical to supporting a putative biosphere. In the past few decades the debate about habitability of Europa has been focused strongly on the thickness of the ice shell. However, an arguably more critical question is: how does the ice shell recycle? New analysis of Europa’s enigmatic “chaos terrains,” indicates that chaos features form in the presence of a great deal of liquid water, and that large liquid water bodies exist within 3km of Europa’s surface comparable in volume to the Great Lakes. The detection of shallow subsurface “lakes” implies that the ice shell is recycling rapidly and that Europa may be currently active. In this presentation, we will explore environments on Europa and their analogs on Earth, from collapsing Antarctic ice shelves to to subglacial volcanoes in Iceland. I will present these new analyses, and describe how this new perspective informs the debate about Europa’s habitability and future exploration.

Speaker:
Yoshihiro Kaneko (UCSD)

Abstract:
Study of the earthquake source brings about a set of fascinating interdisciplinary problems characterized by nonlinearity, a broad range of spatial and temporal scales, rare but catastrophic events, competing physical mechanisms, remote observations, inverse problems, non-uniqueness, and substantial societal significance. The ultimate challenge is to understand and quantify factors controlling the spatio-temporal behavior of active faults, including earthquake nucleation, seismic patterns, and the interaction of seismic and aseismic fault slip. My research aims to address this challenge by developing realistic physical models of earthquake source over several seismic cycles that rely on recent dramatic advances in observations, computational resources, and laboratory experiments. The goal is to use the models in conjunction with seismic, geodetic, and geological observations to constrain earthquake-source properties in terms of experimentally-derived constitutive laws, and then to study the potential set of future behaviors. Here, I will present two examples that illustrate this approach. In the first one, numerical modeling is used to establish the relation between variations in fault friction properties, the pattern of interseismic coupling (which characterizes the degree of fault locking between seismic events), the properties of earthquake sequences, and the observable characteristics of individual seismic events. The second example presents an innovative method for inferring fault friction properties based on comparison of numerical simulations and geodetic observations, which is applied to the central section of the North Anatolian fault (Turkey).

Speaker:
Max Werner (ETH Zurich)

Speaker:
Troy Carter
UCLA

Abstract:
I will give an overview of the challenges associated with harnessing nuclear fusion as a terrestrial power source and the progress that has been made in research in this area. In particular, I will discuss turbulence in magnetically-confined plasmas and how transport associated with this turbulence limits the confinement achievable in current and planned experiments. I will present recent UCLA research that has helped advance our understanding of the basic physics of turbulence and turbulent transport in magnetized plasmas.

Speaker:
P.U.P.A. Gilbert
University of Wisconsin

Abstract:
Mapping the Amorphous-to-crystalline transitions in CaCO3 biominerals with 20-nm resolution One of the most fascinating aspects of calcite biominerals is their intricate and curved morphology, quite different from the rhombohedral crystal habit of geologic calcite. These morphologies, as well as space-filling and greater resistance to fracture, are achieved via amorphous precursor mineral phases (1). In this talk we will show that in sea urchin larval spicules two distinct phase transitions occur, 12 and 23 (2). Both transitions are regulated by inhibiting proteins, which introduce activation barriers between states otherwise spontaneously transforming because they are energetically downhill (3). 1. Y Politi, RA Metzler, M Abrecht, B Gilbert, FH Wilt, I Sagi, L Addadi, S Weiner, and PUPA Gilbert. Mechanism of transformation of amorphous calcium carbonate into calcite in the sea urchin larval spicule. Procs. Natl. Acad. Sci. USA 105, 17362-17366, 2008. 2. AV Radha, TZ Forbes, CE Killian, PUPA Gilbert, and A Navrotsky. Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate. Procs. Natl. Acad. Sci. USA 107, 16438–16443, 2010. 3. YUT Gong, CE Killian, IC Olson, NP Appathurai, RA Metzler, AL Amasino, FH Wilt, PUPA Gilbert. Phase Transitions in Sea Urchin Larval Spicules. Under review.

Speaker:
Michael Jura
UCLA

Abstract:
Knowing that extrasolar planetary systems are common, we would like to learn whether the Earth is normal or distinctive. Bulk Earth is 94% composed of O, Mg, Si and Fe and very deficient compared to the Sun in volatiles such as C and N. With our recent observations of white dwarf stars that have recently accreted tidally-disrupted minor planets that are about 300 km in diameter, we find a similar compositional pattern in extrasolar asteroids. While there must be individual exceptions, in aggregate, the studied extrasolar asteroids also are as “dry”; they probably formed interior to a snow line. Although the current sample is tiny, it appears that bulk Earth is compositionally normal for a rocky body. In the future, we may learn whether extrasolar planetesimals have undergone differentiation, a fundamentally important process in the history of our own planet.

Speaker:
German Prieto
Universidad de los Andes, Bogotá, Colombia

Abstract:
The physical mechanism of intermediate-depth earthquakes is still under debate. In contrast to conditions in the crust and shallow lithosphere, at temperatures and pressures corresponding to depths >50 km one would expect rocks to yield by creep or flow and not by brittle failure, so there has to be a physical mechanism that allows for brittle or brittle-like failure for intermediate-depth earthquakes. Two such mechanisms have been proposed: dehydration embrittlement and thermal shear runaway. Earthquake nests represent a region with high earthquake concentration that is isolated from nearby activity. I will discuss general observations on the three famous intermediate-depth earthquake nests – Vrancea, Hindu-Kush and Bucaramanga. The emphasis will be on the Bucaramanga nest (Colombia) and how high-resolution seismological observations (tectonic setting, precise earthquake locations, focal mechanisms, stress drops, etc.) may provide key constraints on the mechanism responsible. Given the nature and characteristics of this nest, it can be thought as natural laboratory for understanding the physics of intermediate-depth earthquakes.

Speaker:
Dr. Darlene Lim
NASA Ames Research Center

Abstract:
Analog field science and exploration research can approximate the
Earth’s past as well as humanity’s future in space. Such is the case
with the research of the Pavilion Lake Research Project (PLRP). The
PLRP, a multi-disciplinary, science and exploration endeavor, focuses
on understanding the morphogenesis of modern microbialites in Pavilion
Lake, British Columbia, Canada. Over the years, the PLRP has employed a
suite of lab and field based methods to accomplish its scientific and
exploration goals. The field research demands the seamless integration
of science and exploration field activities in an underwater
environment inherently hostile to humans. The physical, mental and
operational rigors associated with PLRP field science and exploration
activities are comparable to extra-vehicular activities (EVA) where
scientific exploration is a key driver. These working constraints are
not simulated, but real and inextricable from the PLRP’s activities.
The PLRPs analog science activities provide a real science setting in
which to inform the development of scientific and mission operation
architectures, train astronauts as field scientists, test technology,
evaluate technical requirements to meet scientific needs, and design
science backroom team protocols.

Darlene will present a synopsis of the PLRP science and exploration
activities with a focus on this past year’s field season at Kelly Lake,
BC, Canada.

Speakers
David Paige and Jean-Luc Margot
Dept. Earth & Space Sciences, UCLA

Abstract:
Profs. Paige and Margot will present new results from the MESSENGER
mission to Mercury, the first spacecraft to orbit the innermost
planet.

Speaker:
Dr. Karel Schrijver
Lockheed-Martin Advanced Technology Center

Abstract:
The Sun’s evolving magnetic field causes variations in solar
irradiance, heliospheric wind, and geospace conditions that range from
seconds-long explosions to billion-year trends. Traces of that
variability can be found in Galileo’s drawings and ancient ice sheets,
while observations of stars like the Sun provide glimpses of what the
Sun did through the ages. This observational material guides us towards
an understanding of the root of solar activity – the dynamo – needed to
understand the Sun-Earth connections.