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Tectonics Laboratory

Tectonics Laboratory. Paul Lundgren, Susan Owen, Danan Dong, Eric Gurrola, Eric Fielding, Zhen Liu, Rowena Lohman, Brian Newport, Paul Rosen, Frank Webb Jet Propulsion Laboratory, California Institute of Technology. Fundamental science questions.

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Tectonics Laboratory

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  1. Tectonics Laboratory Paul Lundgren, Susan Owen, Danan Dong, Eric Gurrola, Eric Fielding, Zhen Liu, Rowena Lohman, Brian Newport, Paul Rosen, Frank Webb Jet Propulsion Laboratory, California Institute of Technology

  2. Fundamental science questions • How does strain accumulate along faults and plate boundaries, and how is it released during the earthquake cycle? • What are the appropriate rheological descriptions of the lithosphere that span different spatial and temporal scales? • What is the relationship between observed short-term geodetic behavior and the formation of long-lived geologic structure? Approach • Focus on time variable deformation and fault mechanics in subduction and diffuse plate boundary zones. • Combine high spatial and temporal resolution deformation maps over broad areas with geodynamic modeling.

  3. Technology Development • Bias-fixed high-rate GPS solutions • True coseismic deformation • Study transients on subdaily time scales • Reprocessed GEONET data with new orbits, better troposheric mapping functions • Better long term (decadal) transient detection. • Smaller seasonal signal in time series • InSAR applications and processing development • InSAR time series development • scanSAR processing • Incorporating InSAR time series into NIF • Critical for transient slip models using So Cal InSAR time series

  4. Geodetic imaging of earthquake cycle deformation

  5. Geodetic imaging of earthquake cycle deformation • Time series analysis challenges: • Common mode error • Seasonal signals • Sub-daily solutions • -Multiple changes in orbit analysis strategy over 10 years.

  6. SoCal time series (preliminary) InSAR time series using WInSAR archived ERS data. Plate boundary profile Oil Santa Ana aquifer Separate tracks require referencing to a common reference frame - either model-based or using GPS

  7. Subduction Zone Processes • Understanding nature of transient deformation • Transient slip detection using NIF • Study of large-spatial-scale Tokai transient • Understand effects of non-uniform rheology on inversions for fault slip • Finite element models of elastic time scale events • Coseismic, short transient events. • Understand interseismic plate coupling in Nankai segment • Inverse solutions based on FEM Greens fcns • Visco-elastic models combining realistic rheologies with great eq. recurrence • Improving understanding of subduction zone fault mechanics, dynamics. • Integration of different time scale (transient, coseismic, interseismic) models.

  8. Diffuse Plate Boundaries • Understand effects of non-uniform rheology on inversions for fault slip • Coseismic, short transient events: Parkfield, Bam • Understand nature of transient deformation. • Use combined InSAR and GPS time series to characterize transient events • Generate an interseismic model for Southern Cal • Combined InSAR and GPS time series, with a FEM approach • Understand source mechanisms of postseismic deformation • Use InSAR time series for Bam EQ postseismic • Compare with Parkfield and other recent large earthquakes

  9. Fault plane parameterization Correlated noise Rigidity structure Eberhart-Phillips and Michael, 1993 Imperial valley atmospheric noise Community fault model, SCEC More accurate error bounds on earthquake/time series parameters (Qeshm EQ location)

  10. Bam 2003 coseismic slip • preferred model two rupture planes • main strike-slip fault beneath surface rupture and city • second oblique thrust projects to surface fold previously mapped • fits seismic waveform analysis • nearly all slip shallower than 8 km Gareth Funning et al., JGR, 2005

  11. Bam aftershocks • aftershocks recorded by local network starting 3 days after 2003 quake • strong motion data from Bam show strong directivity to city • aftershocks all > 6 km, dip west, extend to 20 km • illuminate unruptured deeper fault so continued risk for city Jackson, Bouchon, Fielding et al., GJI, Sept. 2006

  12. Postseismictime series • Descending track 120, 20 epochs Jan. 2004–Mar. 2006, also two ascending tracks • 44 interferograms • plane fit removed from each epoch • referenced to epoch 3 (Mar. 2004) with less atmospheric noise

  13. Post-seismic processes depend on t time since Bam earthquake s -1.4 cm A 2.6 cm τ 0.45 y 1) a + b log(t) 2) s + A (1–exp(-t/τ)) west looking track s is deformation from EQ to ref. 2004/3/17 A is deformation from EQ to infinity τ is time constant

  14. Shallow afterslip model Depth (km) more at AGU postseismic session UTM northing (km) North South

  15. SCIGN stations 3-D fault model (remeshed from CFM) Triangular Network Inversion Filter San Andreas fault region – transient slip rate Jan. 2001- June. 2006 NW SE

  16. Increase of N-S contraction rate in northern Los Angeles Basin Strain rate tensor time series 1.913.6 -0.274.0 9.39 7.27 nanostrain/yr2 Transient deformation around the onshore Oakridge fault in Ventura Basin Map view of the deviation from linear trend E,N,U comp. of position time series at GPS station VNCO Inverted cum. Slip from Network inversion filter

  17. Thanks, and come see our posters!

  18. Available dense GPS networks • Crustal strain vs time (sec, hours, days, years) • interseismic, preseismic (?), coseismic, postseismic, mechanics

  19. Postseismic time series Descending track (west look)

  20. Relationship to JPL Strategic Goals • Enhances InSAR and GPS core competency for the Lab in science and technology areas that have suffered from lack of NASA sponsorship, offsetting deficiencies in these areas and setting the stage for a Solid Earth InSAR mission and advanced GNSS science applications. • Developing the technological infrastructure to maintain JPL science in the forefront of geodynamics research • InSAR time series • InSAR scan-SAR interferometry • Integration into mROI_PAC • High-rate GPS solutions from large networks • GPS analysis using cluster computing • GNSS capability • Builds up solid Earth science at the Lab • Broadens and deepens JPL science in plate boundary processes research. • Enhances numerical modeling capabilities in geodynamics • Hired two post-docs with expertise in geodynamic modeling of plate boundaries • Acquiring state-of-the-art finite element and Network Inversion Filter modeling capabilities • Addressing the key scientific questions of time varying plate boundary deformation and mechanics • Time varying fault and mechanical models for California and western US • Plate coupling and transient slip models in Japan subduction zone • Postseismic deformation and implications for lithospheric rheology (Bam, Landers, Hector Mine, Parkfield) • Will strengthen our ties with Caltech and the Tectonic Observatory • Collaboration on • Modeling (scientific interaction, postdoc selection, meshing and FEM capabilities) • Time series analysis (GEONET analysis, cluster computing, periodic signal analysis) • Building a team with Caltech based on • JPL researchers, Caltech Faculty, JPL and Caltech Post-docs, and computational infrastructure. • Strengthens our position for lead science role on space geodesy missions, such as an InSAR mission • Will strategically position JPL to play a major role in NSF PBO research and in future NASA missions

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