Spring 2009 Seminar Series

11:00am - 12:00pm
1140 Plant Sciences Building

Coffee and tea are served in the Geology Building at 10:30am prior to the seminar.

Friday February 6

Dr. Sujay Kaushal, Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science

"Influence of Land Use, Climate Variability, and Stream Restoration on Nitrogen Dynamics in Watersheds"

Friday February 13

Dr. Stephen Self, National Research Council

"Detection and Effects of Past and Future Super-eruptions"

NO SEMINAR

Friday March 6

Dr. Nadine McQuarrie, Princeton University

"Filling the eastern Himalayan gap:  Structural architecture and kinematics of the Himalayan orogen in Bhutan"

*** SPECIAL AOSC SEMINAR ANNOUNCEMENT ***

Thursday March 12
3:30pm - 4:30pm CSS 2400

Dr. Michael N. Evans, University of Maryland

"What Caused the Late 16th Century Drought Across Western North America?"

Abstract:Can North American "megadroughts", most recently observed in tree ring records from across western North America in the late 16th century, be driven by prolonged ENSO cold phase conditions? If more recent long-term droughts are driven by a different mechanism, there may be potential for even stronger droughts in a greenhouse world. We have applied an ensemble climate field reconstruction technique to the estimation of Pacific sea surface temperatures from a sparse multiproxy network of high resolution marine and terrestrial proxy records. The ensemble conserves the sum of error plus signal variance, despite dramatic changes in the number of proxy datasets available over time. The results may be used to develop forced ensemble atmospheric general circulation modeling experiments designed to test the motivating hypothesis, given realistic error estimates in the reconstructed forcing fields.

Friday March 13

NO SEMINAR

Friday March 20

NO SEMINAR

Friday March 27

Dr. Sang-Tae Kim, University of Maryland

"Searching for Hidden Environmental Changes Using Stable Isotopologues: From Synthetic Aragonite to Martian Meteorites"

Friday April 3

Dr. Olivier Barnouin-Jha, Johns Hopkins University Applied Physics Laboratory

"A multi-disciplinary approach to constraining the origin of fluidized ejecta on Mars"

Abstract: We use experimental and numerical techniques along with topographic data, and images in the visible in and near-infra-red to better understand the factors responsible for the formation of so called "fluidized" craters on Mars.

Friday April 10

Dr. Alex Song, Department of Terrestrial Magnetism, Carnegie Institution of Washington

"Subducting Slab Ultra-Slow Velocity Layer Coincident with Silent Earthquakes in Southern Mexico"

Abstract:Great earthquakes have repeatedly occurred on the plate interface in a few shallow dipping subduction zones, where the subducting and overriding plates are strongly locked. Silent earthquakes (or slow slip events) were recently discovered at the down-dip extension of the locked zone and interact with the earthquake cycle. Here we show that locally observed converted SP arrivals and teleseismic underside reflections sampling the top of the subducting plate in southern Mexico reveal that ultra-slow velocity layer (USL) varies spatially (3-5 km, S wave velocity ~ 2.0-2.7 km/s). Most slow slip patches coincide with the presence of the USL and they are bounded by the absence of the USL. The extent of the USL delineates the zone ofof transitional frictional behavior.

Friday April 17

Dr. Francis Nimmo, University of California Santa Cruz

"What's going on at Enceladus?"

Abstract:The Cassini spacecraft revealed that Enceladus, a small icy moon of Saturn, is unexpectedly interesting. In particular, it is one of only four solar system bodies known to be geologically active: it has south polar geysers spewing water vapour hundreds of km into space. In this talk I will discuss recent theoretical work on Enceladus, focusing on three particular issues: why is it active?; does it have an ocean?; and how has it evolved? The answers are relevant to the astrobiological potential of Enceladus, and may also influence the design of future spacecraft missions.