1. ARTS Seminar June 2, 2011 Ionospheric Observations of Tsunamis Using GPS: Results from Tohoku and Other Recent Events D. A. Galvan 1, A. Komjathy 1, M. P. Hickey 2, P. Stephens 1, A. J. Mannucci 1, Tony Song 1 1 NASA Jet Propulsion Laboratory, California Institute of Technology 2 Department of Physical Sciences, Embry-Riddle Aeronautical University

2. ARTS Seminar June 2, 2011 Outline 1.Tsunami Characteristics as a Natural Hazard 2.Phenomenology: Ocean-Ionosphere Coupling 3.Total Electron Content Measurements 4.Observations 2009 American Samoa Tsunami 2010 Chile Tsunami 2011 Tohoku Tsunami 5.Conclusions 2

3. ARTS Seminar June 2, 2011 Series of ocean waves caused by displacement of large volume of water. (Earthquakes, landslides, underwater nuclear detonations, bolide impacts) Fast: Move through deep ocean at speeds ~200 m/s (~450 mph), amplitudes of several cm in deep ocean. Typical period is 5 – 60 minutes, wavelengths ~ 100 - 400 km. (depending on ocean depth) Can cause significant damage and loss of life 2011 Japan Tsunami  15,327 deaths (8,343 missing) 2010 Chile Tsunami  231 deaths 2009 American Samoa Tsunami  192 deaths 2004 Sumatra Tsunami  230,000 deaths – according to: NGDC http://www.ngdc.noaa.gov/hazard/tsu_db.shtmlhttp://www.ngdc.noaa.gov/hazard/tsu_db.shtml –And Japan National Police Agency http://www.npa.go.jp/archive/keibi/biki/higaijokyo_e.pdf 1. Tsunamis as a Natural Hazard 3

4. ARTS Seminar June 2, 2011 Tohoku Tsunami: March 11, 2011

5. ARTS Seminar June 2, 2011 Tsunami Generation 5 Figure from: http://www.globalsecurity.org/eye/images/tsunami-2.jpg

6. ARTS Seminar June 2, 2011 Tsunami Wave Characteristics 6 http://www.globalsecurity.org/eye/images/tsunami-3.jpg Shallow water velocity equation: Where g = gravity d = depth 198 m/s 22 m/s

7. ARTS Seminar June 2, 2011 Present Day Early Warning System: Deep Ocean Assessment and Reporting of Tsunamis (DART) http://www.ndbc.noaa.gov/dart/dart.shtml 7

8. ARTS Seminar June 2, 2011 Present Day Early Warning System http://www.ndbc.noaa.gov/dart.shtml 2004: 6 Stations 2008 (and present day): 39 Stations operating 8

9. ARTS Seminar June 2, 2011 Motivation: Why add ionospheric observations? DART buoy system is expensive: ~$250,000 per buoy to build DART system cost $12 M to maintain/operate in 2009 (28% of NOAA’s total tsunami-related budget)* Buoys are sparsely distributed, temperamental Data available 84% of time, outages due to harsh weather, human error* GPS Receivers are more abundant, multi-use, low-cost Additional means of observing tsunamis over a broader area could help to validate and improve theoretical model predictions, contributing to tsunami early warning system. *Government Accountability Office (GAO) report, April 2010 http://www.gao.gov/cgi-bin/getrpt?GAO-10-490

10. ARTS Seminar June 2, 2011 2. Phenomenology: Ocean-Atmosphere Coupling Internal Gravity Waves Ocean waves produce atmospheric pressure waves large enough to perturb ionospheric electron densities ~1%. Daniels (1952). Figure from Hines, 1972 Hines (1972) produced model of Internal Gravity Waves that can propagate to ionospheric altitudes based on surface disturbances. Peltier and Hines (1976): Suggested that tsunamis could generate internal gravity waves that could be detected in the ionosphere using ionosondes. 10

11. ARTS Seminar June 2, 2011 Atmosphere as Low-pass Filter 11 Brunt Vaisala Frequency: g = gravity, θ = potential temperature. ~5 mHz (period 3.3 min) at sea level. Typical buoyancy frequency of the atmosphere. IE: any buoyancy wave must have lower frequency to propagate upward. Typical ocean “noise” of 1 m amplitude has periods of several seconds. Too short. Tsunamis have longer periods, typically 5 minutes – 30 minutes (3 mHz – 0.5 mHz) Atmosphere acts as a low-pass filter, allowing tsunami-driven gravity waves to propagate upward. Figure from Kelley, 2009 after Yeh and Liu, 1974

12. ARTS Seminar June 2, 2011 Tsunami-driven Traveling Ionospheric Disturbances (TIDs) From Artru et al., 2005 12

13. ARTS Seminar June 2, 2011 Seismic Disturbances in the Atmosphere 13 Figure from Garcia et al., 2005 3,400 m/s Sound speed model from Artru et al, 2005

14. ARTS Seminar June 2, 2011 3. Total Electron Content 14 From Komjathy Ph.D. Dissertation, 1997.

15. ARTS Seminar June 2, 2011 Previous Observations Artru et al., 2005a: Ionospheric perturbation observed on June 24, 2001 after an 8.2 M earthquake in Peru. The color points show the TEC variations at the ionospheric piercing points. A wave-like disturbance is propagating towards the coast of Honshu. 15

16. ARTS Seminar June 2, 2011 Previous Observations Challenge: TIDs are common and difficult to distinguish from tsunamigenic IGWs, except by time of occurrence. Artru et al., 2005a 16

17. ARTS Seminar June 2, 2011 Modeling Neutral-Plasma Coupling Strong zonal background winds affect TEC perturbation: Tsunamis propagating East-West (perturbations ~0.02 TECU) Tsunamis propagating North-South (perturbations ~3 TECU). (Hickey et al., 2009). Figures from Hickey et al., 2009 N e perturbations for Eastward propagation including mean winds. Max value: 10 9 m -3. N e perturbations for Northward propagation including mean winds. Max value: 3 x 10 9 m -3. 17

18. ARTS Seminar June 2, 2011 Modeling Neutral-Plasma Coupling Strong zonal background winds affect TEC perturbation: Tsunamis propagating East-West (perturbations ~0.02 TECU) Tsunamis propagating North-South (perturbations ~3 TECU). (Hickey et al., 2009). Figures from Hickey et al., 2009 18

19. ARTS Seminar June 2, 2011 Data Type: Total Electron Content (TEC) from International GNSS System (IGS) stations -30-second TEC data from 355 active dual-frequency GPS receivers. -Data processed through Global Ionospheric Mapping (GIM) algorithm at JPL -For simultaneous bias identification/removal (satellite and receiver),

20. ARTS Seminar June 2, 2011 Regional Networks Source: Scripps Orbit and Permanent Array Center (SOPAC) GPS Data Archive, UCSD http://sopac.ucsd.edu/cgi-bin/somi4i 20 Source: Japanese GPS Earth Observation Network (GEONET) Array Over 1200 stations http://terras.gsi.go.jp/gps/geonet_top.html GEONET Array

21. ARTS Seminar June 2, 2011 Streaming 1-second data availability Currently up to 130 stations worldwide providing 1-second realtime data. http://www.gdgps.net/http://www.gdgps.net/, ftp://cddis.gsfc.nasa.gov/pub/gps/data/highrate

22. ARTS Seminar June 2, 2011 Methodology Estimate time at which tsunami should arrive in a given region. (simple 200 m/s projection, MOST model predictions, etc.) Process GPS TEC data from regional receivers using JPL Global Ionospheric Mapping software. Fit high-order polynomial to time series; look at residuals. Apply bi-directional band-pass filter: 0.5 – 5 mHz (33.3 – 3 min period) Plot filtered TEC as a function of distance/time to search for possible tsunami-driven variations. 22

23. ARTS Seminar June 2, 2011 4. Observations TEC Observations: ASPA with GPS 40 Earthquake: 17:48 UT Tsunami observed at Pago Pago tidal gauge: 18:12 UT 23

24. ARTS Seminar June 2, 2011 TEC Observations: ASPA with GPS 50 24

25. ARTS Seminar June 2, 2011 TEC Observations: ASPA with GPS 58 25

26. ARTS Seminar June 2, 2011 TEC Observations: ASPA with GPS 34 26

27. ARTS Seminar June 2, 2011 American Samoa: Near Epicenter 200 m/s Internal Gravity Waves (Tsunami) 1000 m/s Acoustic Waves (Earthquake) 3400 m/s Rayleigh Waves(Earthquake) 27

28. ARTS Seminar June 2, 2011 MOST model of Tsunami Propagation: American Samoa, 2009 Movie available at: http://nctr.pmel.noaa.gov/samoa20090929/20090929_samoa_a.mov 28

29. ARTS Seminar June 2, 2011 American Samoa Tsunami 9/29/09 Observed at Hawaii Galvan et al., 2011 (JGR)

30. ARTS Seminar June 2, 2011 American Samoa Tsunami 9/29/09 Observed at Hawaii (zoomed in)

31. ARTS Seminar June 2, 2011 American Samoa: Observed at Hawaii 31

32. ARTS Seminar June 2, 2011 American Samoa Tsunami 9/29/09 Observed at Hawaii (hodochron plot)

33. ARTS Seminar June 2, 2011 MOST model of Tsunami Propagation Chile 2010 Movie available at: http://nctr.pmel.noaa.gov, Courtesy NOAA CTRhttp://nctr.pmel.noaa.gov 33

34. ARTS Seminar June 2, 2011 Ionospheric waves observed at Chile 34

35. ARTS Seminar June 2, 2011 Chile Event Observed at Hawaii >40 deg Elevation angle 35

36. ARTS Seminar June 2, 2011 Chile Tsunami: Observed at Japan 36

37. ARTS Seminar June 2, 2011 Chile Tsunami: Observed at Japan 37

38. ARTS Seminar June 2, 2011 Theoretical Model Results Ocean Surface Displacement (m) Vertical TEC Spectral full-wave model (SFWM), Hickey et al., 2009, using input wave form from Peltier and Hines, 1976, and period/velocity from DART buoy.

39. ARTS Seminar June 2, 2011 Hickey Model Compared with Data Filtered VTEC (TECU) Universal Time (2/28/2010)

40. ARTS Seminar June 2, 2011 Tohoku Tsunami 3/11/2011 MOST model of Tsunami Propagation Movie available at: http://nctr.pmel.noaa.gov, Courtesy NOAA CTR http://nctr.pmel.noaa.gov

41. ARTS Seminar June 2, 2011 Tohoku Earthquake and Tsunami 3/11/2011 Ionosphere Observations Bi-directional filter

42. ARTS Seminar June 2, 2011 Tohoku Earthquake and Tsunami 3/11/2011 With Tony Song’s Model

43. ARTS Seminar June 2, 2011 TEC Observations over Japn 3/11/2011 30-second data Earthquake: 05:46:23 UT

44. ARTS Seminar June 2, 2011 Pre-quake ramp-up is a dual-pass filter artifact Earthquake: 05:46:23 UT

45. ARTS Seminar June 2, 2011 Pre-quake ramp-up is a dual-pass filter artifact Earthquake: 05:46:23 UT

46. ARTS Seminar June 2, 2011 Tohoku Earthquake and Tsunami 3/11/2011 with model Single Direction Filter

47. ARTS Seminar June 2, 2011 Tohoku Earthquake and Tsunami 3/11/2011 with model Single Direction Filter (trimmed)

48. ARTS Seminar June 2, 2011 Japan Tsunami 3/11/2011 Distance vs. Time plot UT Mar 11, 2011 Distance from Epicenter

49. ARTS Seminar June 2, 2011 Japan Tsunami 3/11/2011 Distance vs. Time plot UT Mar 11, 2011 Distance from Epicenter

50. ARTS Seminar June 2, 2011

51. ARTS Seminar June 2, 2011

52. ARTS Seminar June 2, 2011 Song ModelIonosphere Observations

53. ARTS Seminar June 2, 2011 Song Model overlaid on TEC observations Note main model tsunami wavefront parallel to strongest ionosphere wavefront. At a given distance from epicenter, Ionosphere signature appears about 24 minutes after ocean wave.

54. ARTS Seminar June 2, 2011 Period dependence of ionospheric arrival From Hines, 1967

55. ARTS Seminar June 2, 2011 Observations Summary American Samoa Tsunami (2009) Observed at: Hawaii Not Observed : near epicenter, California Chile Tsunami (2010) Observed at: Hawaii, Japan Not Observed: near epicenter, California Japan Tsunami (2011) Observed at Japan, but EQ signature complicates Elsewhere in process. 55

56. ARTS Seminar June 2, 2011 5. Conclusions Tsunami-driven variations in ionospheric TEC have been observed after the American Samoa Tsunami of 9/29/2009, the Chilean tsunami of 2/27/2010, and the Japan tsunami of 3/11/2011. Theoretical models predict tsunami-driven TID’s. (Occhipinti et al., 2008; Hickey et al., 2009; Mai and Kiang, 2009) Amplitudes tend to be ~1-2% of background TEC. Observations: range from ~ +/- 0.1 – 3 TECU, ~1 – 10% background. Tsunami-driven ionospheric disturbances ARE DETECTABLE. BUT there are challenges to overcome if this is to become a real time early warning asset. 56

57. ARTS Seminar June 2, 2011 Future Work Compare observations with model predictions for additional regions. Study more events to determine consistency of detection. (Why we see it under some conditions and not others.) Automated algorithm to monitor for tsunami-driven TID’s. Additional avenues of observation: COSMIC, Galileo, GLONASS, new signal structure Real-time observations of tsunami-driven TID’s using NASA Global Differential GPS System http://www.gdgps.net 57

58. ARTS Seminar June 2, 2011 Acknowledgements Dr. Attila Komjathy NASA ROSES Grant # NNH07ZDA001N- ESI(Tsunami Imaging Using GPS Measurements) Dr. John LaBrecque (NASA HQ) Dr. Vasily Titov and Dr. Yong Wei (NOAA Center for Tsunami Research) Dr. James Foster (University of Hawaii) Dr. Giovanni Occhipinti 58