Crustal Strain and Deformation National Meeting Summary Report

Crustal Strain & Deformation Science
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Chairs:

Roland Burgmann (UC Berkeley)
David Sandwell (UC San Diego)
Sucker: Me (Matt Pritchard, Cornell University)

What we did:

• Review 2002 plan

Brainstorm lists of:

• 1) (Achievable) Big-picture science goals
• 2) Potential workshop topics
• 3) (Risky) Frontier science goals

Review of 2002 Science Plan: (2001 Snowbird Meeting Workshop Report)

EarthScopeʼs facilities include:

• SAFOD (San Andreas Fault Observatory at Depth
• USArray (United States Seismic Array)
• PBO (Plate Bound ary Observatory)
• InSAR (Interferometric Synthetic Aperture Radar) - NASA Spacecraft proposal was not funded. NSF, NASA and USGS support the purchase of InSAR data from the European Space Agency and the Canadian Space Agency.

InSAR: Earthscope’s missing leg

Three-legged chair, sculpture by David Ireland Why leg is missing is “mysterious” in the artwork and in Earthscope http://www.stretcher.org/archives/r5_a/2004_03_19_r5_archive.php)

Craig Dobson (NASA) reports:

• NASA has an airborne InSAR that has data in hand from western U.S. sites
• Potential DESDynI launch in 2015
• Continued need for data from foreign assets

2002 Science Topics

• 1) lithosphere rheology
• 2) fault rheology
• 3) stress in the lithosphere: absolute stress and how heterogeneous?
• 4) transients in the lithosphere
• 5) role of fluids in lithospheric stress (poroelastic)
• 6) how do faults interact?
• 7) impact of tectonic deformation on fluid flow in the crust

2009 Science Plan:

Big-picture ideas!

• 1. What has been learned with EarthScope already opens up new questions
• 2. Non-tectonic processes including glacial & hydrological phenomena tie to climate change and related processes
• 3. Develop continuous deformation fields at high sampling rate for improved studies of transient deformation events. Motivation for real-time?
• 4. Spatial density of strain fields is still lacking. More semi-continuous networks to densify coverage? More data from surveyors, etc. InSAR velocity field over all western-US. Improve knowledge of geologic deformation. More focal mechanisms.
• 5. Spectrum of fault slip behavior deserves deeper, interdisciplinary exploration (from steady creep, episodic slow slip events to seismic slip).
• 6. Role of compliant fault zones: How widespread? How many?
• 7. Complementary data: More downhole instrumentation. Add gravity

2009 Science Plan:

"Frontier" ideas!

• 1. Identify opportunities for Broader Impact, Education and Outreach efforts. (all)
• 2. Improve vertical GPS sensitivity and relate to geodynamic processes LiDAR survey of whole US would be of interest. (26)
• 3. Elastic vs. Permanent deformation! Geologic information, LiDAR, focal mechanisms, and conventional geodesy all needed. (25)
• 4. Offshore geodesy - implications for fault mechanics, partitioning of deformation, seismic hazard, etc. (24)
• 5. 4D Seismology & Strain: Time-dependent ambient noise. Accelerations in GPS velocity fields and annual cycles (24)
• 6. Eastern US deformation: Many new topics (13)
• 7. Why does the crust deform where and how it does? Heat flow, lithology, etc. (13)
• 8. Global partnerships and integration world-wide. (8)
• 9. Geodesy at depth vertical strain at depth. (5)
• 10. Precursory processes, triggering mechanisms etc. (4)
• 11. More Tiltmeters in tectonic regions (e.g., at GPS sites along SAF). (4)
• 12. “Ambient noise geodesy” - small motions of sites (2)
• 13. Foreshocks are common: Can we target moderate (M5) earthquakes often, given that 20% of them may turn out to be foreshocks? (4)
• 14. Core strain from magnetic field. (1)

2009 Science Plan:

Thematic Workshop/Institute ideas!

• 1. Velocity fields, strain maps and integration:

• 1. Unifying all available campaign and continuous GPS data for comprehensive velocity field and time series products
• 2. Comprehensive integration of GPS and InSAR
• 3. Comparison of strain rate maps - separation of strain rate into elastic earthquake-cycle strain (steady and time dependent) and permanent strain rate
• 4. Integration of strain rate models and 3-D structure from other Earthscope elements (anisotropy, tomography etc.)

• 2. Spectrum of fault slip behavior: Observations and models of slip behaviors.
• 3. Loading processes affecting vertical deformation: atmosphere, hydrology