Understanding and Responding to Earthquake Hazards

1. Understanding and Responding to Earthquake Hazards Carol A. Raymond Paul R. Lundgren Søren N. Madsen Jet Propulsion Laboratory And John B. Rundle University of Colorado

2. Summary • Discuss ongoing Global Earthquake Satellite System Study (GESS) • Objectives of the study are to develop a linked science and technology program plan that would lead to understanding of faults and fault systems and achieve short-term, targeted earthquake forecasting by 2020. • Develop detailed science requirements with science community input (EarthScope and beyond) • Develop system architecture concepts for both short term (next 5 years) and long term (next 20 years)

3. Observing Crustal Dynamics • Surface change (deformation) is the key observable • Considered the highest priority of the NASA Solid Earth Science community (InSAR everywhere, all the time) • Models and seismicity yield third dimension (depth) • Electromagnetic, IR/thermal emissions may indicate state of stress • More research is needed, and systematic data analysis of high resolution data sets • Addressed by ASTER, MODIS, Demeter, swarm

4. Future Observing System • Seismicity yields information on the energy released in discrete events and illuminates fault planes • Need dense digital seismic network (USGS) • Global Positioning System (GPS) measurements track surface motions on specific points with high time resolution • Need dense, continuous GPS arrays (SCIGN, PBO) • Interferometric Synthetic Aperture Radar (InSAR) measures the deformation of the surface as a continuum, but usually with poor time resolution • Need an InSAR constellation to improve temporal resolution

5. Surface Deformation Science Requirements Real Aperture Radar Increasing accuracy Increasing temporal resolution 4-8 days < 24 hrs 1 sec

6. Surface Deformation Measurement Requirements

7. Observations to Prediction • Community Modeling • Environment • Model validation • Model evolution • Forward prediction • Grid-based computing • Data Mining • General Earthquake Model (GEM) is prototype InSAR Seismicity GPS electric field magnetic field thermal IR Dynamic Earthquake Hazard Assessment (monthly? to annual/USGS) Physics-based models of precursory signals FEMA, CA OES and Int’l Aid Community

8. Responding to EQ Hazards • Earthquake hazard assessments: • Prioritize retrofitting of vulnerable structures • Update building codes • Increase earthquake drills for emergency services and public (schools) • Public education campaigns • Increase monitoring of hazardous areas • Disaster: • Rapid assessment of damage in all weather via decorrelation maps received on handheld devices • Updated hazard assessment due to stress transfer and loading of nearby faults

9. Community Modeling Faults Can Be Modeled as Interacting Systems:Virtual California Southern California Seismicity Fault Representation VC provides an assessment of the space-time complexity of seismicity and fault system behavior Courtesy Paul Rundle and John Rundle Physical Review Letters, 2001

10. Pre- minus Post-Seismic Displacements: Synthetic InSAR The pre-seismic state is subtracted from the post-seismic state The differences are concentrated along the portions of the San Andreas that are about to initiate earthquakes The observable difference is ~ 3 CM Stable sliding (stress smoothing) preceding earthquakes can be measured Courtesy John Rundle

11. InSAR Concept Alternatives • Low Earth Orbit (LEO) 780 km elevationECHO/LightSAR class satellite Cheapest option, 8-day repeat • Enhanced Low Earth Orbit (LEO+)1325 km elevation, 6-day repeat50–80% larger targeted range, stable orbitsTechnology as LEO but larger antenna and power • Constellation of LEO+ satellites (2/4/8… satellites) • Geosynchronous SAR (GeoSyncSAR) 35789 km elevation,1-day repeat, 1 satellite covers ±60° in longitude5500 km “targetable” swath on either side of ground track Very large antenna (30 m @ L-band), moderately large power (65 kW DC)

12. LEO Accessibility versus GEO Coverage>95% coverage in 8 hrs with 3 sats >95% access in 8 hrs with 8 sats

13. Geosynchronous Modes • High-resolution:Stagger bandwidth over consecutive days => 80 MHz bandwidth => 2.5 meter range resolution at 45° • Dual-side Scan SAR 11000 km combined swath=>100 meter resolution @ 25 looks • Scan-SAR with 3 aspect angles (45° forward, broadside, 45° backward) of 2800 km swath on both side of nadir=>100 meter resolution @ 8 looks • Spotlight mode dwelling beam for hours on target, for disaster management

14. 3-GEO Instantaneous

15. Technology Challenges • Sub-centimeter (!!) tropospheric water vapor delay corrections • Radar or radiometer data alone accurate to 2-3 cm level of range delay • Co-boresighted IR/microwave sounding may yield 1 cm accuracy in delay • Mesoscale models that ingest sounding and radar data will likely deliver the sub-cm correction • GPS, permanent scatterers and corner cubes all improve the wet delay correction • 30-m antenna (deployable) for GEO • Analysis and component development • New processing system for GEO

16. Flexible Hexagonal Antenna • L-band/X-band membrane antenna aperture • Flexible T/R module • Ultra high efficiency SiC Class-E/F power amplifiers • Agile 2-D beam scanning • MEMS heat pipes for thermal management • Optical RF/DC signal distribution • Inflatable/deployable structures • Integrated solar panels Membrane Solar Arrays Inflatable/deployable struts L-band RF membrane aperture X-band Shared-aperture comm antenna Symmetric telescoping booms

17. GESS Roadmap • Observations • 2003-06: ECHO or ECHO-like InSAR satellite (EarthScope) • 2006-2010: 2-3 satellite LEO or LEO+ InSAR constellation; magnetometer constellation • >2010: GEO InSAR constellation? • Technology • Large deployable antennas • Processing system for GEO observations • High resolution atmospheric models ingesting radar data