1. Using GPS buoys for tsunami warning - an overview Dr. Ken Hudnut Geophysicist U. S. Geological Survey Pasadena, California Earthquake Research Affiliates Partners’ Meeting Caltech6 May 2005

2. Acknowledgements Caltech: Prof. Kerry Sieh, John Galetzka, and Dr. Chen Ji USGS: Dr. Lucy Jones, Dr. Eric Geist, NEIC Staff Dr. Kristine Larson, Univ. Colorado; Ben Remondi And many others at NOAA and worldwide through the internet Photo by John Galetzka Caltech Tectonic Observatory

3. NOAA buoy SystemDART

7. Caltech Tectonic Observatory GPS ArraySuGAr On-land GPS stations are essential

8. GPS buoy systems NOAA DART buoys are expensive and high maintenanceNOAA DART buoys are expensive and high maintenance GPS buoys developed by GFZ and Univ. Tokyo groupsGPS buoys developed by GFZ and Univ. Tokyo groups GPS can be used for large numbers of low-cost buoys to complement existing systemGPS can be used for large numbers of low-cost buoys to complement existing system NavCom-AXYS contract for US Navy (NAVOCEANO); 2 cm inshore, 10 cm offshoreNavCom-AXYS contract for US Navy (NAVOCEANO); 2 cm inshore, 10 cm offshore NOAA-USGS testing program for warning applicationNOAA-USGS testing program for warning application Tie in with existing earthquake and weather monitoring and alertsTie in with existing earthquake and weather monitoring and alerts

9. GPS precise real-time positioning Robust ambiguity resolution Phase-differential Range of only 30 km before - recently stretched to 300+ km by several people; now it’s practical Courtesy of Choi and Larson; base station is ~400 km away

10. HA-NDGPS tests NOAA/NGS with Remondi and DOT/FHWA support - IGEB funding Hagerstown to Chesapeake Bay at 245 km range real-time demo

11. Gyros (IMU or INS) with GPS Stable gyro technology (RLG) is costly ($80K) but MEMS-gyro and IFOG are low-cost and approaching accuracyStable gyro technology (RLG) is costly ($80K) but MEMS-gyro and IFOG are low-cost and approaching accuracy Barbour & Schmidt, 1998

12. California Scenarios 1.Central or South America M9 - as tsunami passes Isla Guadelupe it is accurately measured by diff. GPS buoys tied to CGPS site GUAX 2.Alaska, Kamchatka or Japan M9 measured at buoys near Hawai’I and Farallons - Bay Area predictions improved 3.Cascadia M9 - waves obs. in detail so that shallow- water and edge effects are observed (and also predicted) much better

14. Padang - what to do? Photo by John Galetzka Caltech Tectonic Observatory

15. Photo by John Galetzka Caltech Tectonic Observatory Inexpensive package of GPS/INS can be added (after R&D and testing) to existing NOAA buoys offshore of So. Calif. to complement other Instrumentation for earthquake and tsunami early warning systems SoCal - What to do?