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Modeling Advances in the SCEC Geodesy Community Workshop

Conveners: Rowena Lohman and Jessica Murray
Dates: September 9, 2012 (08:00-12:00)
Location: Hilton Palm Springs Resort, Palm Springs, CA
SCEC Award and Report: 12094

SUMMARY: This workshop addressed three major SCEC4 Tectonic Geodesy modeling activities: the Community Geodetic Model (CGM), Geodetic Transient Detection, and a new Geodetic Source Inversion exercise.

Community Geodetic Model (8:00-9:30am)
This portion of the workshop focused on a new SCEC4 initiative, the Community Geodetic Model (CGM). The CGM will be a time-dependent geodetic data product that provides a reference frame for a variety of SCEC research including development and testing of the Community Stress Model, transient detection algorithms, and studies of time-varying deformation. The initial focus of this effort will be on bringing together GPS and InSAR time series to exploit the complementary spatial and temporal features of these two data types. Ultimately other data types (such as strain data) may be incorporated as appropriate and if feasible.

Following an introduction by Jessica Murray, Kaj Johnson discussed the contribution that the CGM could make to deformation modeling used in seismic hazard assessments like UCERF3. Increased spatial density of observations in some locations could help better constrain block models and quantify distributed strain within blocks..

Murray and Scott Baker, respectively, provided overviews of existing GPS and SAR data coverage and the prospects for data availability (particularly SAR data) going forward. Three additional presentations (by Alejandro Gonzales, Brendan Crowell, and Yuri Fialko) highlighted recent SCEC-supported campaign GPS efforts in southern California and Baja, Mexico that were designed to target specific topics such as characterizing the postseismic deformation from the El Mayor Cucapah earthquake and quantifying fault creep.

Finally, Roland Bürgmann spoke about ways to integrate GPS and InSAR data into a unified data product. A variety of approaches exist, and all are to some degree model-dependent. One challenge for the development of the CGM will be to identify the most promising approaches for southern California and provide appropriate uncertainty information for the resulting product accounting for the error sources inherent in both data types.

The primary goal of this portion of the workshop was to introduce the CGM to the SCEC community and initiate discussion. A follow-on workshop involving scientists who are likely to be directly involved in developing and applying the CGM is envisioned for 2013. A goal for that workshop will be establishing timelines and a work plan for generating the CGM.

Geodetic Transient Detection (10:00-11:00am)
The transient detection section of this workshop began with a quick summary by Lohman of the strengths and weaknesses of the existing automated algorithm that has been running at the CSEP testing center for the past year. The workshop then highlighted two approaches by Holt and Herring that are nearly at the point where they can be automated, with some discussion of the hurdles to automation that continue to exist. Ji and Herring’s approach uses template signals and seeks the time series for similar instances – they are, therefore, necessarily limited to a finite set of signal types and will likely have multiple tests running simultaneously.

Geodetic Source Inversion Validation (11:10am-12:00pm)
Rowena Lohman introduced the motivation and concept for a seismic source validation exercise using geodetic data. In a manner similar to that used in the source inversion validation exercise run by Martin Mai, Morgan Paige and Danijel Schorlemmer, this exercise will involve the generation of synthetic data with a varying degree of complexity, which will be provided to participants.

Initially, participants will be given some knowledge about the source geometry and noise characteristics, to ensure that data input/output formats are understood and that the same conventions for Green’s functions are being used. Data will be generated using progressively more complicated source geometries, slip distributions and data noise characteristics, and results can be submitted through an online interface.

Midway through the session, Brendan Meade presented an example of a new direction in source inversion validation that can be tested using this approach. By seeking the most spatially compact solution that is consistent with the data, he is able to explore a different end member model from the spatially smooth ones that are typically found in inversions that rely on regularization through roughness or minimum length constraints.

AGENDA

Presentation slides may be downloaded by clicking the pdf links following the title. PLEASE NOTE: Slides are the author’s property. They may contain unpublished or preliminary information and should only be used while viewing the talk.

Community Geodetic Model (CGM) Presenters
08:00-08:10 Introduction/Overview of motivation and goals/target audiences Jessica Murray
08:10-08:30 CGM as input for the Uniform California Earthquake Rupture Forecast (UCERF) and Community Stress Model (CSM) [Murray] [Johnson] Kaj Johnson, Jessica Murray
08:30-08:50 Geodetic Coverage: GPS and InSAR [Murray] [Baker] Jessica Murray, Scott Baker
08:50-09:15 Approaches available for integrating GPS and InSAR
Quantifying uncertainties - what precision is needed and possible?
Roland Bürgmann
09:15-09:30 General Discussion  
09:30-10:00 Break  
Geodetic Transient Detection  
10:00-10:10 Introduction/Summary of effort so far Rowena Lohman
10:10-10:30 Presentations by groups on results from their approaches [Holt 2011] [Holt 2012] [Herring/Ji] William Holt,
Tom Herring/Kang Ji
10:30-10:40 Presentation on "operational" portion of effort Masha Liukis
10:40-10:50 General Discussion  
10:50-11:00 Break  
Geodetic Source Inversion Validation  
11:10-11:20 Introduction and motivation Rowena Lohman
11:20-11:30 New approaches Brendan Meade
11:30-11:40 Unveiling of initial data sets and framework for comparisons Rowena Lohman
11:40-12:00 General Discussion  
12:00 Adjourn  

PARTICIPANTS:

Duncan Agnew (IGPP/SIO/UCSD)
Bob Anderson (CSSC/CEA)
Gregg Armstrong (Georgia Tech)
Scott Baker (UNAVCO)
Sylvain Barbot (Caltech)
Joseph Berg (CSUSB)
Roger Bilham (U of Colorado)
Mike Blanpied (USGS)
Yehuda Bock (UCSD)
Cecilia Booker (U.S. Navy)
Jayne Bormann (UNR)
Jim Brune (UNR)
Roland Bürgmann (UC Berkeley)
Simmie Chehal (CSUN)
Xiaofei Chen (UST China)
Ray Chuang (Indiana)
John Conrad (UCR)
Michele Cooke (U Mass)
Eric Cowgill (UC Davis)
Tom Crane (CSUSB)
Brendan Crowell (UCSD)
Jared DeBock (UC Boulder)
Dan Determan (USGS)
Ksenia Dmitrieva (Stanford)
Andrea Donnellan (JPL)
Laura Fattaruso (U Mass)
Yuri Fialko (UCSD)
Mike Floyd (MIT)
Gareth Funning (UCR)
David Gill (SCEC / USC)
Javier Gonzàlez-Garcìa (CICESE)
Alejandro Gonzalez-Ortega (CICESE)
Jennifer Haase (UCSD/SIO)
Elizabeth Haddon (CGS)
Elizabeth Hearn
Justin Herbert (U Mass)
Tom Herring (MIT)
Alejandro Hinojosa-Corona (CICESE)
James Hollingsworth (USC)
Bill Holt (SUNY-Stony Brook)
Steve Husa (Fontana HS)
Walter Imperatori (KAUST)
Dave Jackson (UCLA)
Junle Jiang (Caltech)
Kaj Johnson (Indiana)
Tom Jordan (USC)
Frank Jordan, Jr. (CSULA)
Ronnie Kamai (PEER)
Katherine Kendrick (USGS)
Tyler Kent (UNR)
Katere Khodavirdi (UCLA)
Rich Klimczak (PG&E)
Shannon Klotsko (UCSD/SIO)
Keith Knudsen (USGS)
Franklin Koch (Caltech)
Sebastien Leprince (Caltech)
Dunzhu Li (Caltech)
Xiangyu Li (UCSB)
Yen-Yu Lin (Caltech)
Ting Lin (Stanford)
Eric Lindsey (SIO)
Zhen Liu (JPL/Caltech)
Qiming Liu (UCSB)
Masha Liukis (SCEC / USC)
Rowena Lohman (Cornell)
Yingdi Luo (Caltech)
Rainer Luptowitz (CSUSB)
Dave Lynch (USGS)
Shuo Ma (SDSU)
Scott Marshall (App State)
Jeremy Maurer (Indiana)
Andreas Mavrommatis (Stanford)
Sally McGill (CSUSB)
John McRaney (SCEC / USC)
Brendan Meade (Harvard)
Meghan Miller (UNAVCO)
Alex Morelan (UNR)
Jessica Murray (USGS)
Erika Noll (UCR)
Shunichi Nomura (ISM)
Susan Owen (JPL)
Jay Parker (JPL)
Samuel Reed (PCC)
Yuval Reuveni (NASA)
Phoebe Robinson (Harvard)
Marshall Rogers-Martinez (Columbia)
David Sandwell (UCSD)
Paul Segall (Stanford)
Gina Shcherbenko (Stony Brook U)
Zheng-Kang Shen (UCLA)
Joshua Spinler (Arizona)
Feng Su (USBR)
Mark Swift (SBCM)
Orlando Teran (CICESE)
Wayne Thatcher (USGS)
Xiaopeng Tong (IGPP/SIO)
Swetha Veeraraghavan (Caltech)
Chris Walls (UNAVCO)
Matt Wei (WHOI)
Jim Whitcomb (NSF)
Yi-Hsuan Wu (UC Davis)
Wenzheng Yang (Caltech)
Qian Yao (UCSD/SDSU)
sayokoi Yokoi (ERI Tokyo)
Sang-Ho Yun (NASA JPL)
Yuehua Zeng (USGS)

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