Below are the bios and presentation summaries for the EarthScope distinguished speakers of the 2015/2016 academic year. The EarthScope Speaker Series is funded by the National Science Foundation.
2015-2016 EarthScope Speaker Series Schedule
|Grand Valley State University||10/04/15||Adrian Borsa|
|University of Oregon||10/07/15||Vedran Lekic|
|Oberlin College||10/07/15||Melodie French|
|Oregon State University||10/08/15||Heather De Shon|
|University of Wisconsin-Whitewater||10/09/15||Fan-Chi Lin|
|University of Wisconsin||10/09/15||Fan-Chi Lin|
|Penn State University||10/13/15||Reed Burgette|
|Midwestern State University||10/15/15||Anne Egger|
|Portland State University||10/28/15||Reed Burgette|
|Boston College||10/30/15||Heather De Shon|
|University of Florida||11/04/15||Adrian Borsa|
|Marshall University||11/12/15||Melodie French|
|University of New Mexico||11/13/15||Fan-Chi Lin|
|Georgia Tech||1/21/16||Fan-Chi Lin|
|University of Colorado||2/03/16||Melodie French|
|Auburn University||2/04/16||Heather De Shon|
|Indiana University||2/08/16||Heather De Shon|
|University of Utah||2/11/16||Reed Burgette|
|University of Hawaii at Manoa||2/17/16||Fan-Chi Lin|
|Kent State||2/19/16||Heather De Shon|
|University of Arizona||2/25/16||Reed Burgette|
|New Mexico Institute of Mining & Technology||3/10/16||Adrian Borsa|
|University of Minnesota||3/10/16||Melodie French|
|Rice University||3/24/16||Fan-Chi Lin|
|Fullerton College||4/12/16||Adrian Borsa|
|University of Pennsylvania||4/15/16||Melodie French|
|University of Wisconsin-Madison||4/29/16||Reed Burgette|
|Colorado State University||5/05/16||Adrian Borsa|
Dr. Heather DeShon (See More)
Huffington Dept. of Earth Sciences
Southern Methodist University
Dr. Heather DeShon is a seismologist at Southern Methodist University whose research focuses on understanding earthquake initiation and rupture complexity. She uses high-resolution earthquake relocation and tomography to explore the spatial and temporal relationships between seismic source characteristics and structural variability. Her background in using local amphibious seismic networks to understand subduction seismogenic zone processes has more recently been applied to studies of intraplate seismicity and lithospheric structure in the central US. More broadly, her research interests are aimed at improving the characterization of seismic and tsunami hazard. Heather received her B.S. in Geophysics and Mathematics at Southern Methodist University and a Ph.D. in Earth Sciences (Geophysics) from the University of California-Santa Cruz.
Presentation: Death of a Fault: A Comparison of Seismicity in the New Madrid Seismic Zone and North Texas
Increased seismicity rates across the central United States have raised scientific questions and local and national concerns about the impact of shale gas production on infrastructure and subsurface structures such as faults. But the central US is not historically aseismic and intraplate faulting is not uncommon. This talk explores similarities and differences between the intraplate New Madrid seismic zone, host to the large (M7+) earthquakes of 1811-1812 and focus of the Earthscope NELE experiment, and ongoing earthquake sequences occurring in the Fort Worth (Barnett Shale) Basin. Both New Madrid seismicity and North Texas earthquakes occur along reactivated ancient faults located in the basement granites and overlying sedimentary units and release natural tectonic stresses. New Madrid has a long paleoseismic record of large earthquakes. In contrast, North Texas had no credible felt earthquakes prior to 2008 and the recent swarms have been linked to local wastewater injection associated with shale gas extraction (2008/2009 DFW; 2009 Cleburne; 2013 Azle); studies of the 2014/2015 Irving-Dallas and 2015 Venus sequences are ongoing. Both regions are currently monitored – New Madrid by the USGS and CERI permanent network and Earthscope stations and North Texas by a ~40 station temporary network operated by SMU with support from the USGS. High-resolution earthquake locations, waveform correlation, and source characteristics are combined with information on subsurface geology and fault structure, and 3D pore pressure modeling to provide insight into the relationship between fluid migration at depth and modern microseismicity along pre-existing fault structures. Understanding if and/or how injection of fluids into the crystalline crust reactivates faults have important implications for seismology (i.e., fault physics), the energy industry, and society. Comparisons of potentially induced sequences like North Texas with natural intraplate seismic zones like New Madrid may yield important insights to understanding the long-term hazard associated with the increased seismicity in the Central US.
Dr. Adrian Borsa (See More)
Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
Adrian Borsa is a researcher at the Institute of Geophysics and Planetary Physics at the Scripps Institution of Oceanography. His work aims to describe how the shape of Earth's surface is changing at timescales of seconds to decades, and to link observed change to geophysical processes associated with phenomena ranging from earthquakes to climate change. Dr. Borsa's expertise includes the collection and analysis of geodetic data from many sources, including permanent and mobile GPS sensors, airborne lidar, and satellite altimeters. He is also actively involved in the calibration and validation of elevation measurements from several generations of satellite altimeters, and has made the remote salar de Uyuni in Bolivia his field home for the past decade in support of this work. Dr. Borsa took an atypical route to science, beginning with a B.A. in Government, an M.A. in International Relations, and an early career in international business focused on Japan and the United States. He received his PhD from the Scripps Institution of Oceanography in 2005, was posted at the US Geological Survey during his post-doc, and moved to Boulder, CO to take a management position within NSF's EarthScope program. He returned to Scripps and to full-time scientific research in 2012.
Presentation: What EarthScope's Plate Boundary Observatory can tell us about water resources in the western United State
Following a year of above-average precipitation in 2011, the western United States entered into drought in late 2012 and has yet to emerge. The severity of the current drought is focusing public attention on known water resource challenges in the West and is changing assumptions about how water use should be monitored and regulated. Despite this new interest in water management, snowpack and groundwater — key components of water storage — are sparsely instrumented and cannot yet be adequately monitored from space. As a result, a new paradigm is emerging for observing water in the western US. Because the solid earth responds elastically to hydrological loading, changes in water storage can be inferred from surface displacements measured using the Global Positioning System (GPS). EarthScope¹s Plate Boundary Observatory includes a continuous GPS network that has proved to be an exceptional tool for monitoring the spatiotemporal evolution of the hydrological cycle. Seasonal changes in water loading have long been known to drive annual cycles of GPS site motion, but changes over both longer and shorter periods are detectable and yield insights into weather and climate phenomena from individual storms to multiyear drought. Scientific GPS networks such as the Plate Boundary Observatory, originally built to study crustal displacement from plate tectonics and volcanic processes, could soon become an important extension of the global hydrological observing system.
Dr. Fan-Chi Lin (See More)
Geology and Geophysics
University of Utah
Fan-Chi Lin is a seismologist at the University of Utah, where he has been an assistant professor in the Department of Geology and Geophysics since 2013. His main scientific interest is using seismic signals to improve our current understanding of the earth’s interior structure. The main focus of his research is developing innovative seismic interferometry and array processing techniques to extract new information that can be used to constrain the structure of the earth, from the surface to the core. After receiving his B.S. and M.A. in physics from National Tsing Hua University, Taiwan, and Drexel University, respectively, he obtained his Ph.D. in geophysics from the University of Colorado in 2009, where he worked under the supervision of Prof. Michael Ritzwoller on ambient noise and surface wave tomography. In 2011, he received a Director’s Post Doctoral Fellowship at the California Institute of Technology to continue his research on seismic interferometry and surface wave tomography with Prof. Victory Tsai and Robert Clayton. In 2015, he received the Charles F. Richter Early Career Award from the Seismological Society of America. His ongoing projects include imaging the Yellowstone magma plumbing system, fault zone structure, shallow crustal structure, and inner core structure using seismic interferometry and seismic tomography.
Presentation: Seismic Interferometry and Tomography Across USArray – Imaging Interior Earth Structure from Upper Crust to Inner Core
Over the last 10 years, the large-scale dense seismic network of EarthScope USArray Transportable Array has progressively been deployed with a ~70 km station spacing to cover the entire contiguous United States. The unprecedented amount of high quality broadband seismic data allows seismologists to image detailed earth structure on various different scales from shallow to deep. In particular, innovative seismic analyzing techniques have been developed to better utilize the array configuration and to extract new constraints on the structure of the earth that were not available before. In this presentation, I will first discuss some of the recent developments in seismic interferometry and tomography. I will explain how seismologists can now extract useful seismic signals from diffusive wavefields, such as the ambient noise wavefield and the earthquake coda wavefield. I will then demonstrate how these new developments combined with data from USArray improve our understanding of the lithospheric structure across the US, the Yellowstone magma plumbing system, and the earth’s inner core structure.
Dr. Melodie French (See More)
Department of Geology
University of Maryland
Melodie French is an NSF Earth Sciences Postdoctoral Fellow at the University of Maryland, College Park. She is interested in the mechanical and fluid transport properties of fault zones using methods from experimental rock deformation and structural geology with particular concern for constraining seismic hazards. Her work is focused on determining how mechanical properties, fluid flow, and rock fabric lead to diverse fault slip behavior. Ongoing projects include: creep and seismic slip mechanisms in fault rock recovered from 2.7 km depth during the San Andreas Fault Observatory at Depth (SAFOD), the controls of fluid pressure on shear deformation of subduction zone rocks at the conditions of episodic tremor and slip (ETS), and fluid-injection triggereed seismicity. Melodie received her B.A. in Physics with a minor in Geology from Oberlin College, an M.S. in Geology from the University of Wisconsin, Madison, and a Ph.D. in Geophysics from Texas A&M University.
Presentation: Creep and the potential for seismicity along the central segment of the San Andreas Fault
The central segment of the San Andreas Fault (SAF) currently accommodates displacement by a combination of aseismic creep and microseismicty. In the past, earthquakes on the adjacent locked segments of the SAF have arrested at the boundaries of the creeping segment, indicating that it is a barrier to rupture propagation. Although historically aseismic, we still do not know whether a sufficiently large rupture could initiate on a locked segment and propagate into and through the creeping segment of the SAF.
The San Andreas Fault Observatory at Depth (SAFOD) program recovered fault rock from two clay-rich gouge zones at 2.7 km depth along the creeping segment of the SAF, near its boundary with the southern locked segment. The Southwest Deforming Zone (SDZ) and Central Deforming Zone (CDZ) are cumulatively four meters thick and are believed to accommodate most of the plate boundary displacement at SAFOD. I present results from deformation experiments conducted on gouge from the CDZ at shear rates that range from in-situ creep to seismic slip. The strength of the gouge varies with shear rate and this strength variation reflects an evolution in deformation processes that is recorded in the microstructure of the sheared gouge. I will discuss how the mechanical and microstructural properties are critical to constraining the potential for seismic slip along the creeping segment of the SAF. Finally, I will discuss how results from the SAFOD community have revealed the long-term evolution and seismic cycles of creeping plate boundary faults.
Dr. Reed Burgette (See More)
Department of Geological Sciences
New Mexico State University
Reed Burgette studies neotectonics on geodetic (years to decades) and geologic (thousands to hundreds of thousands of years) timescales. His research interests center around understanding how deformation is distributed spatially in plate boundary zones, and temporally through the seismic cycle associated with individual structures. For the shorter time scale, Reed uses historical leveling and tide gauge observations as well as GPS and satellite altimetry to measure vertical deformation rates. He uses high resolution observations of topography coupled with Quaternary dating methods to measure deformation rates averaged over multiple seismic cycles. Reed's group is working along the west coast of the U.S., in the Tien Shan mountains of central Asia, and locally in the Rio Grande Rift. He received a B.A. in Geology and Biology at Whitman College. Reed’s interests in seismic hazards and understanding how active faults work led to a Ph.D. at the University of Oregon. He then worked as post-doctoral researcher at the University of Tasmania, applying satellite geodesy to questions of crustal deformation, sea level rise, and Antarctic ice sheet mass balance. He joined the faculty of New Mexico State University in 2013.
Presentation: Ups and downs of the U.S. West Coast: Implications of eight decades of vertical deformation measurements for seismic hazards and sea level impacts
Along active plate boundaries, vertical deformation of the crust results from strain accumulation between major earthquakes. Observations of this vertical deformation are important to constrain where faults are currently locked and may slip in future earthquakes, particularly when integrated with horizontal deformation imaged by GPS. Additionally, the vertical motion of the land along the coast can either enhance or counteract the effects of the global process of sea level rise on a local basis. In this presentation, I will show how observations of relative sea level change made at tide gauges and repeated leveling surveys can be used to measure the pattern and rate of vertical deformation over timescales of several decades to over a century. I will also review satellite-based estimates of vertical deformation and sea level rise made over the past two decades to assess the level of agreement between techniques and examine changes in deformation rates over time. Tectonic deformation is the dominant signal along the Cascadia portion of the coast, and is consistent with along-strike variation in locking behavior on the plate interface. Rates of vertical motion are lower along the transform portion of the plate boundary and include anthropogenic effects, but there are significant tectonic signals, particularly in the western Transverse Ranges where the crust is shortening across reverse faults. I will highlight emerging insights and outstanding questions derived from the vertical deformation rate field for understanding hazards from earthquakes and coastal inundation related to sea level rise.