2. Tide gauge measurements and analysis of the Indian Ocean tsunami on the Pacific coast of South America A.B. Rabinovich 1,2 and R.E. Thomson 1 1 Institute of Ocean Sciences, Sidney, B.C. Canada 2 P.P. Shirshov Institute of Oceanology, Moscow, Russia

3. Maximum tsunami amplitudes computed by V.V. Titov (PMEL/NOAA) Tsunami of the December 26, 2004 recorded in the World Ocean [Titov et al., Science, 2005]

4. MOST model of the December 26, 2005 tsunami Numerical model by V.V. Titov (PMEL/NOAA)

5. Location of tide gauge stations on the coast of South America

6. Station Name Sampling Interval Train Wave Height (cm) Wave period (min) Tsunami arrival time (27/12) Tsunami travel time Baltra I., Galapagos Is., Equador 2 1 st 2 nd 14 36 34 41 06:26 11:04 29h 27min 34h 05min Callao, Peru2 1 st 2 nd 20 68 38 36 05:49 08:23 28h 50min 31h 24min Arica, Chile2 1 st 2 nd 25.5 72 46 39 04:02 08:28 27h 03min 31h 29min Iquique, Chile2 1 st 2 nd 13 24.5 50 14;37 03:35 09:45 26h 36min 32h 46min Antofagasta, Chile2 1 st 2 nd 7.5 27.5 46 44 03:25 10:25 26h 26min 33h 26min Caldera, Chile2 1 st 2 nd 13 22 31 16.5 03:16 06:46 26h 17min 29h 47min Coquimbo, Chile2 1 st 2 nd 20.5 36 33 34.5 01:53 07:39 24h 54min 30h 40min Valpraiso, Chile2 1 st 2 nd 8.5 18 32 36.5 01:04 05:10 24h 05min 28h 11min San Antonio, Chile2 1 st 2 nd 8.5 15 50 54 ~00:12 ~11:12 ~23h 13min ~34h 13min Talcahuano, Chile2 1 st 2 nd 24 43 33 irregular 01:35 09:49 24h 36min 32h 50min Corral, Chile2 1 st 2 nd 19 29 34 36 01:49 06:11 24h 50min 29h 12min Punta Corona, Chile21 st <5~2001:4524h 45min 2004 Sumatra tsunami: Observed wave parameters

7. The 2004 Indian Ocean tsunami records on the Pacific coast of South America (1)Long ringing (>2 days) (2) Slow energy decay (3) Unclear first arrival (4) “Train” structure (5) Maximum waves in 8-30 hrs after the first arrival (in the second or third train)

8. The 2004 tsunami as recorded in the Indian Ocean West Indian OceanCentral and East Indian Ocean (1)Relatively short ringing (1-1.5 days) (3) Maximum waves are in the very beginning (4) Fast amplitude decay(2) First arrival is abrupt and clear

9. North Pacific Ocean Aleutian and Kuril Islands Pacific coast of Canada

10. Recorded tsunami wave heights along the coast of South America Indian Ocean (Sumatra) tsunami of December 26, 2004

11. Tsunami and background spectra “…The spectra of tsunamis from different earthquakes are similar at the same location but are quite different for the same event for nearby locations…” [Omori, 1902, and many others…]

12. Northern group of stations Reconstructed source functions

13. Southern group of stations Reconstructed source functions

14. Averaged source function While individual tsunami spectra are significantly different for different stations, the reconstructed “source function” is supposed to be independent of local topographic effects and be related to the actual spectral characteristics of the source. Good agreement of this function calculated for various sites and different regions supports this assumption.

15. Reconstructed source functions based on Canadian records (BC coast)

16. Wavelet plots of the 2004 Indian Ocean tsunami (1) Time: 25/12 18h – 28/12 18h Periods: 2.5h – 0.20h

17. Wavelet plots of the 2004 Indian Ocean tsunami (2) Time: 25/12 18h – 28/12 18h Periods: 2.5h – 0.20h

18. Wavelet analysis of the Indian Ocean records Time: 25/12 12 h – 28/12 12 h Periods: 2.5 h – 0.20 h (Cocos1: 1.67 h – 0.13 h )

19. Conclusions: 1. The 2004 Sumatra tsunami was the first global- scale tsunami in the “instrumental era” and it was observed throughout the World Ocean, including the North Pacific, North Atlantic and Antarctic Oceans. 2. This tsunami was clearly measured by tide gauges along the entire Pacific coast of South America with wave heights ranging from a few cm (Punta Corona) to 72 cm (Arica).

20. 3. The resonant characteristics of the shelf and coastline strongly determine the observed features of tsunami waves, in particular wave heights and periods; maximum waves were observed at sites having eigen (natural) periods from 30 to 60 minutes. 4. The recorded tsunami waves are characterized by long ringing (>2days), slow energy decay, and clear train wave structure with maximum waves related mainly to the second or third train (8-30 hours after the first arrival); from this point of view these records are quite different from those observed in the Indian Ocean but similar to those observed in the North Pacific and North Atlantic.

21. 5. The observed spectra of tsunami waves had peaks significantly different for different stations; in contrast, these peaks were in good agreement with background peaks at the same sites. Significant tsunami oscillations were observed at stations with local resonant periods of 30-50 min, apparently corresponding to the periods of arriving tsunami waves. 6. In contrast to individual tsunami spectra, the reconstructed “source function” is found to be very consistent and almost independent of local topographic effects and is apparently related to the spectral characteristics of the source.