Department of Geology
Department of Geology, University of Maryland
Towards a pixel-by-pixel view of North America's changing surface using geodetic imaging
Abstract: For centuries, measurement of the shape of the Earth (called the science of geodesy) was necessarily time consuming. Even with new technologies like the Global Positioning System (GPS), vast portions of the Earth remain infrequently monitored for movement. Recently, a new form of geodesy has rapidly developed whereby image pairs can be compared to infer movements of the Earth's surface. Called geodetic imaging, the synoptic aircraft or satellite views allow large regions to be surveyed densely without any human setting foot in the area. Imaging geodesy encompasses several different types of methods including Interferometric Synthetic Aperture Radar (InSAR) as well as the automated comparison of SAR and optical images via pixel tracking. InSAR can image sub-centimeter deformation of the Earth's surface every 1-20 meters over areas spanning hundreds to thousands of kilometers. Pixel tracking is a very complementary tool to InSAR-- although the sensitivity to deformation is less (decimeter instead of sub-centimeter in a given image pair) and the horizontal spacing is coarser, it can be applied to both radar and optical images and often works when InSAR does not – for example, in areas that have large displacements or changes to the radar scattering properties of the ground. InSAR has allowed vast areas of the Earth's surface to be monitored frequently for deformation for the first time and this presentation will highlight some of the discoveries in North America and elsewhere, selected with input from the host institution. Possible topics include earthquakes/tectonics, magmatic processes in the Basin & Range and globally, landslides, glaciers (especially in Alaska), groundwater, changes in vegetation, and human-induced ground deformation. A US InSAR mission was part of the original Earthscope plan. While the US InSAR mission (currently called DESDyni-R) is not likely to launch until 2019, Earthscope (along with NASA and others) has facilitated access to InSAR data over North America from several foreign satellite missions from 1992-present. There will soon be more than 300 Terabytes of raw SAR imagery available through UNAVCO and the Alaska Satellite Facility. Most of this data is from the Japanese ALOS mission which had a radar wavelength of 23 cm that is capable of making coherent interferograms over most of North America for the first time. This presentation will discuss how to get access to that data, how to set up a processing capability, and what types of problems this data can and cannot be used to address. Interferograms of the host institution will be presented.
February 1, 2013
Tales from a hydrologist with a mid-life crisis: playing in international development banking and how a sabbatical lead to a career re-focus on sustainability
Abstract: In this talk, I go over my recent experience working inside multilateral development banks (World Bank and Interamerican Development Bank), and how different events and trends in the evolving fields of water, environment, climate and sustainability have influenced and affected my career over the past 20 years. More importantly, I focus on the practice of international development banking as the closest thing I can describe as encompassing "end-to-end" sustainability, how I am looking at curriculum and instructional innovations as a result of this experience, some recent promising results, and what I see lying ahead as challenges and opportunities in interdisciplinary education and research.
February 8, 2013
Tracking linkages between tectonic uplift, chemical weathering, and atmospheric CO2 consumption with Ca isotopes: Southern Alps, New Zealand
March 1, 2013
*** J.V. Loperfido canceled because of USGS travel policies installed in response to the sequester ***
Lower crustal H2O control on the genesis of mafic to andesitic and adakitic arc magmas
Abstract: At volcanic arcs, fluids released from the subducting slab lower the solidus of the mantle wedge and cause melting. Further, slab melts may infiltrate the mantle wedge, and have been suggested to generate “adakitic” (residual garnet) signatures at some arc volcanoes. However, experimental work indicates that the garnet stability field will expand in the lower overriding crust in the presence of somewhat less hydrous melts, suggesting that such signatures may also develop at crustal levels. Geothermometry and plagioclase hygrometry of mafic eruptives from southwest Japan are used here to demonstrate that the adakitic compositions of associated intermediate magmas are of lower crustal origin due to a decrease in the water content of mafic parental melts, and not generated by partial melting of the eclogitic subducting slab at elevated temperatures. Further, the concept of two-pyroxene pseudo-decompression paths (PDPs) is introduced, and using MELTS modeling it is shown that the crystal cargo in many arc magmas is taken up from previous intrusives into rapidly rising, superheated melts. Finally, several future research topics are presented, with emphasis on the use of isotopic studies to trace the origin of magmatic and hydrothermal components and the timing of magmatic evolution.
March 8, 2013
Depths, temperatures & durations: petrologic constraints on rates of orogenic processes
March 15, 2013
Marvelous Moons: Geologically Active Worlds of the Outer Solar System
April 5, 2013
Geophysical structure of an oceanic core complex- tectonic, magmatic, & hydrologic processes at Atlantis Massif, Mid-Atlantic Ridge 30°N
April 12, 2013
In the wake of a snowball glaciation and on the eve of the Cambrian explosion: Biological and environmental evolution in the Ediacaran Period
April 19, 2013
Geochemical Ins and Outs of Subduction Zones.
The coordinator for the Colloquium Series is Dr. Laurent Montesi. You can contact him at montesi AT umd.edu