DamageMap Prototype Using Real-time GPS Point Positioning Hudnut, K. W., E. Safak, A. Borsa, J. Langbein, K. Stark, D. Barseghian, I. Stubailo, M. Kohler, P. Davis Strong Motion Forum EERI Annual Conference Universal City, California 9 February 2007

foundation for real-time structural damage detection and response GPS network infra- structure forms the foundation for real-time structural damage detection and response System design & performance tests Telemetry upgrades Algorithm develop- ment and tests Implementation

Sensor technology GPS Gyro Accelerometer position displacement velocity acceleration Frequency response

Proper transducers for DamageMap: accelerometers, GPS, gyros, tiltmeters Langbein & Bock (2003) Courtesy of John Langbein (USGS)

GPS high-rate (1 Hz) analysis Larson, Billich and Choi - see Ji et al. Sidereal filtering (Larson, Choi) Stacking (Billich) Significant reduction in long-period drift Compares well now with our static GPS displacements

Doubly-integrated seismic vs Doubly-integrated seismic vs. GPS for Parkfield 2004 (co-located @ PHOB) Raw GPS solution in blue Filtered GPS in green Seismic in red (Boore) These show results prior to final GPS analysis step of stacking, shown previously

Erdal Safak (USGS)

Factor Building at UCLA Prototype for DamageMap PI’s Erdal Safak, Monical Kohler and Paul Davis

Viper Shuttle Ashtech Z-12 NavCom rx’s

Initial GPS Data from Factor Building Y RMSE = 5 cm X RMSE = 9 cm 100 times better than normal GPS accuracy (SPS now near PPS performance of 6-20 m @ 95% w/ S/A off) Available worldwide $1400/yr.

Real-time StarFire Post-processed (TRACK)

Multi-taper power spectra (TRACK) Multipath: - red noise - peaks from large individual reflectors 5.5 hrs. 2 seconds

Slider tests GPS antenna moved along a track Precisely recorded displacements and times Real-time and precisely post-processed data

Gyros and MEMS with GPS Stable gyro technology is costly but MEMS-gyro and FOG are lower cost and approaching accuracy Barbour & Schmidt, 1998

Summary Future earthquake monitoring systems will allow faster and better response Tools support rapid and accurate decision-making by emergency responders DamageMap concept Measure structural damage directly - don’t need to know anything else - ‘quick & easy’ and simple, robust reliable design obtain more accurate displacement observations new instrumentation for dynamic and static displacement address deficiencies due to double-integration of accelerometer records R&D effort for DamageMap instrumentation - we completed an initial demonstration of PPP GPS using USGS Venture Capital and ANSS start-up funds, but R&D program funding support has not been maintained and major funding and long-term support for implementation has not yet been identified We are far from being prepared for a Big One in California - it is time to “step it up” - use new technology, fix problems ahead of time

Ken Hudnut Dept. of the Interior - U. S. Geological Survey 525 South Wilson Ave. Pasadena, CA 91106 626-583-7232 hudnut@usgs.gov