Observations of the trans-Pacific tsunami on 11 March 2011 by the French Polynesia and New Caledonia tide gauges.

Following the Mw 8.9 magnitude earthquake that occurred on 11 March 2011 at 5h46 UT close to the Honshu coast in Japan, the tsunami that crossed the Pacific was observed in real time by tide gauges installed in New Caledonia and French Polynesia.

 

Modelling of the tsunami: passage time and height of waves:

Map showing passage time (in hours) Source : NOAA
Map showing passage time (in hours) Source : NOAA
 
 
 
 
Height of waves at high water (not reflecting the complexity and height of waves locally at the coasts) Source : CEA/DASE
Height of waves at high water (not reflecting the complexity and height of waves locally at the coasts) Source : CEA/DASE

network of tide gauge in French Polynesia and New Caledonia:

Network of tide gauges in French Polynesia and New Caledonia (March 2011)
Network of tide gauges in French Polynesia and New Caledonia (March 2011)
Network of tide gauges in New Caledonia (March 2011)
Network of tide gauges in New Caledonia (March 2011)
 

Observations from tide gauges in French Polynesia (Hours UT):

Station Tide gauge (prs, pr2 : pressure sensor ; rad, rad2 : radar sensor) Arrival time (passage time) Maximum amplitude (Hour) Wave Period
Nuku Hiva (Marquises)
Marigram Nuku Hiva
17h49 TU (12h03) 1,48m (18h24 TU) 14 min
Hiva Oa (Marquises)
Marigram Hiva Oa
18h18 TU (12h32) 1,55m (18h56 TU) 14 min
Huahine
Marigram Huahine
17h03 TU (11h17) 0,32m (17h53 TU) 4min, 10min
Rangiroa (Tuamotu)
Marigram Rangiroa
17h18 TU (11h32) 0,41m (18h28 TU) 6 min
Papeete (Tahiti)
Marigram Papeete
17h18 TU (11h32) 0,40m (18h21 TU) 10 min
Vairao (Tahiti)
Marigram Vairao
17h25 TU (11h39) 0,33m (18h29 TU) 20 min
Tubuai (Iles Australes)
Marigram Tubuai
17h57 TU (12h11) 0,27m (19h41 TU) 8 min, 13 min
Rikitea (Gambier)
Marigram Rikitea
19h57 TU (14h11) 0,38m (21h08 TU) 17 min

Observations from tide gauges in New Caledonia (Hours UT):

Station Marigram (prs : capteur à pression ; rad : capteur radar)
Nouméa
Marigram Nouméa
Hienghène
Marigram Hienghène
Ouinné
Marigram Ouinné

Analysis of tide gauge records from the Marquesas Islands :

Nuku Hiva Hiva Oa
Plot of time signal of height of water (at top) and of filtered signal of tide height (at bottom)

Plot of time signal of height of water (at top) and of filtered signal of tide height (at bottom)

Plot of time signal of height of water (at top) and of filtered signal of tide height (at bottom)

Plot of time signal of height of water (at top) and of filtered signal of tide height (at bottom)

Arrived at 17h49 (TU)

Amplitude of first wave: 0.5 m

Maximum amplitude observed = 1.5 m(3rd wave)

Max crest to trough height observed = 2.5 m

Arrived at 18h18 (TU)

Amplitude of first wave: 0.48 m

Maximum amplitude observed = 1.2 -1.3 m(2nd, 3rd, 4th wave)

Max crest to trough height observed = 3 m(2nd wave)
Representation of spectrum

Representation of spectrum

Representation of spectrum

Representation of spectrum

Wave periods between 13.5 and 15 minutes.

Two main frequency intervals (↔ periods):

- [0.95 -1.3] mHz ↔ [13-17.7] min: corresponding to first waves (max)

- 2.3 mHz ↔ 7 min
Time frequency representation

Time frequency representation

Time frequency representation

Time frequency representation

 

References:

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