Analysis of the US Plate Boundary Observatory GPS Network

Geo-Science, Remote Sensing Society and co-sponsored with Microwave Theory and Techniques Society – 6:00PM, Wednesday, 18 March

Analysis of the US Plate Boundary Observatory GPS Network

Thomas Herring, Professor of Geophysics, Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA  tah@mit.edu

In 2004, the National Science Foundation started installation of the Plate Boundary Observatory (PBO) that would span the US portion of the Pacific-North America plate boundary. A decade later, the observatory is fully installed and operated for 5 years. There are approximately 900 new GPS sites added for the observatory and the PBO analysis centers located at Central Washington University and New Mexico Institute of Mining and Technology process ~1800 GPS sites per day made up from stations from pre-existing scientific GPS networks and Continuously Operating Reference Sites (CORS) coordinated by the National Geodetic Survey. Recently, the PBO analysis centers finished reprocessing the data from these ~1800 sites starting with data collected in 1996. We present results from this large regional network. For the main PBO sites, the median weighted root-mean-square (WRMS) scatter of the daily position estimates in a North America Reference frame is less than 1.0 mm horizontally and 4.5 mm vertically after estimating offsets due to earthquakes and antenna changes, postseismic motions for the larger earthquakes and annual sine and cosine terms.   Many signals and various classes of the noise can be seen the time series of these GPS position estimates. We will examine some of the signals that range from rapid earthquake displacements, with 5Hz positioning possible; slow postseismic deformation; slow transient events on the Cascadia subduction zone and in volcanic regions, to the “drying out” of the Western United States that reveals itself as an uplift of the whole region as the weight of the missing water is removed. We also examine some of the noise sources that arise from growing vegetation, snow on antennas and some antenna failures that generate position time-series that can be confused with geophysical signals. Examining the characteristics of the recorded GPS signals can often identify these noise sources. We conclude by discussing analysis methods that can be used to understand these data and separate the noise from the signals.

Thomas A. Herring

Professor of Geophysics, Department of Earth, Atmospheric and Planetary Sciences.

Email: tah@mit.edu

Phone: 617.253.5941

Office: 54-322

Education: Ph.D., Earth and Planetary Sciences, Massachusetts Institute of Technology, 1983 | M., Surveying, University of Queensland, 1978 | B., Surveying (First Class honors), University of Queensland 1971

Positions Held: Professor of Geophysics, MIT (1997-Present) | Associate Professor of Geophysics, MIT (1992-1997)| Kerr-McGee Associate Professor of Geophysics, MIT (1989-1992) | Research Associate, Harvard University (1983-1989)| Visiting Scientist, Division of National Mapping, Australian Department of Energy and Resources (1986) | Research Assistant, MIT (1979-1983) | Teacher, Physics and Mathematics, Cushing Academy (1972-1974)

Awards: Fellow AAAS (2013), Vening-Meinesz Medal, European Geophysical Union (2007) | Bomford Prize, International Association of Geodesy (1995) | Macelwane Medal, American Geophysical Union (1991) | NASA Group Achievement Award, Crustal Dynamics Project (1986 & 1993) | Australian Postgraduate Research Award (1977)

| S.E. Reilly Prize in Surveying (1975) | Commonwealth University Scholarship (1973)

Recent Service: Chair NASA Space Geodesy Program Committee (2013-2015), IERS Analysis Coordinator (2010-2018) | Member, NRC Committee on National Requirements for Precision Geodetic Infrastructure (2008-2009) | Member, AGU Fellows Committee (2006-2008) | Chair, AGU Whitten Medal committee (2004-2006) | Member PBO Transform siting committee (2003-2008) | EarthScope/PBO working group member (2001-2005) | National Geodetic Survey Research Review Panel (2001) | Co-Chair, NRC panel on Availability and Usefulness of NASA’s Space Mission Data (2001-2002) | Member, NASA Solid Earth Sciences Working Group (2000-2002) | Scientific Director, UNAVCO (2000-2002)

Publications: Over 70 referred publications, two edited books, over 15 referred conference proceedings, and 15 other major publications.

The meeting will be held at the MIT Lincoln Lab Cafeteria, 244 Wood Street, Lexington, MA.

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