• GPS-Aided and DART-Ensured Real-time(GADER) Tsunami Early Detection System
Program Disasters Program
PI / Institution Y. Tony Song / Jet Propulsion Laboratory
Start Date October 1, 2014
End Date September 30, 2017
  • Summary

    Early tsunami warning critically hinges on rapid analysis of the triggering earthquake, but unfortunately, even precise knowledge of the earthquake¿s location and magnitude is not enough to predict a tsunami¿s power (scale) that is needed for effective early warnings. Recently, we have proposed directly using coastal Global Positioning System (GPS) network to infer the seafloor displacements due to large earthquakes and to determine a tsunami¿s power (scale) for issuing warnings before the tsunami reaches coastal areas [Song 2007]. This innovative method has been successfully tested: (1) in a NASA pilot program¿the GPS-aided Real-Time Earthquake and Tsunami (GREAT) Alert System; (2) during the events of the 2010 Chilean M8.8 earthquake and the 2011 Japanese M9.0 earthquake; and (3) during the Stage 1-Feasibility study of this project.This report summarizes the progress has been made during the Stage 1-Feasibility study and lays out the plan for transferring the technology to decision-making agencies: NOAA PMEL and PTWC. The feasibility study uses the existing GPS-aided alert system of NASA and the Deep- ocean Assessment and Reporting of Tsunami (DART) system of NOAA for tsunami scale determinations. The goals of the developed system are two folds:¿ Improve near-field early warnings and save lives. Note that most of the tsunami victims are local. The GPS approach directly estimate seafloor displacements, aiming to predict tsunami scales immediately following the earthquake and enabling an early alert to local communities before the tsunami reaches shore.¿ Reduce false alarms and increase reliability. To avoid possible bias from the land- based GPS measurements of the earthquake, nearby ocean-based DART measurements of tsunami height will be assimilated into the system based on the recently tested all-source Green¿s function (ASGF) to verify the GPS-aided alert scale.The combination of these two existing real-time systems (NASA and NOAA) offers the best solution for early detection and early cancelation. The combined system has been successfully tested with two independent platforms:1. Using PMEL¿s tsunami prediction system (MOST), it is shown that the GPS approach and the DART-inversion agree within 95% range, exceeding our initial expectation. NOAA tsunami experts Vasily Titov and Rachel Tang led the feasibility testing.2. Using Canadian ASGF method, we successfully demonstrated the feasibility and reliability of the combined automation system in the 2011 Japanese Tsunami case. The results have been published in JTech [Xu and Song 2013].These tests demonstrated that completing the GADER system is a low risk, innovative and practical project that aims to mitigate one of the most catastrophic natural disasters. It strongly aligns with the NASA Applied Sciences Program¿s priority objectives to improve disaster forecasting, response, and mitigation by using data from existing real-time operational systems: NASA¿s Global Differential GPS (GDGPS) System and NOAA¿s DART system. Significant national and global societal benefits will follow from the completion of the joint NOAA/NASA project.