Kumar Simant

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Tide gauge measurements and analysis of Tide gauge measurements and analysis of the Indian Ocean tsunami on the Pacificthe Indian Ocean tsunami on the Pacific

coast of South Americacoast of South AmericaA.B. RabinovichA.B. Rabinovich1,21,

2 and R.E. Thomsonand R.E. Thomson11

1 Institute of Ocean Sciences, Sidney, B.C. Canada2

P.P. Shirshov Institute of Oceanology, Moscow, Russia



>

-2 m

G a u g e c o a s t a l

h e i g h t s

M o d e

la m p l i t u d e

7 0c m

6 05 04 03 02 01 00

0 . 0 5 m

Maximum tsunami amplitudes computed by V.V. Titov (PMEL/NOAA)

Tsunami of the December 26, 2004Tsunami of the December 26, 2004

recorded in the World Oceanrecorded in the World Ocean

[Titov et al., Science, 2005]



MOST model of the December 26, 2005 tsunami

Numerical model by V.V. Titov (PMEL/NOAA)



Location of tide gauge stations on the coast of South America



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 1st

2nd

14

36

34

41

06:26

11:04

29h 27min

34h 05min

Callao, Peru 2 1st

2nd

20

68

38

36

05:49

08:23

28h 50min

31h 24min

Arica, Chile 2 1st

2nd

25.5

72

46

39

04:02

08:28

27h 03min

31h 29min

Iquique, Chile 2 1st

2nd

13

24.5

50

14;37

03:35

09:45

26h 36min

32h 46min

Antofagasta, Chile 2 1st

2nd

7.5

27.5

46

44

03:25

10:25

26h 26min

33h 26min

Caldera, Chile 2 1st

2nd

13

22

31

16.5

03:16

06:46

26h 17min

29h 47min

Coquimbo, Chile 2 1st

2nd

20.5

36

33

34.5

01:53

07:39

24h 54min

30h 40min

Valpraiso, Chile 2 1st

2nd

8.5

18

32

36.5

01:04

05:10

24h 05min

28h 11min

San Antonio, Chile 2 1st

2nd

8.5

15

50

54

~00:12

~11:12

~23h 13min

~34h 13min

Talcahuano, Chile 2 1st

2nd

24

43

33

irregular

01:35

09:49

24h 36min

32h 50min

Corral, Chile 2 1st

2nd

19

29

34

36

01:49

06:11

24h 50min

29h 12min

Punta Corona, Chile 2 1st <5 ~20 01:45 24h 45min

2004 Sumatra tsunami: Observed wave parameters



The 2004 Indian Ocean tsunami recordson 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)



The 2004 tsunami as recorded in theIndian Ocean

2 0 0 c m

December 2004

S e a l e v e l

E

Port Louis (2 m in)

Lamu (4 min)

Pointe LaRue (4 min)

Salalah (4 min)

Zanzibar (4 min)

06 12 18

West Indian Ocean

2 0 0 c m

Hanimaadhoo (2 min)

Male (4 min)

Gan (4 min)

Colombo (2 min)

Cocos (1 min)

Diego Garcia (6 min)

December 2004

S e a l e v e l

E

06 12 18

Central 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



S e v e r o K u r i l s k

2

0

c

m

T A T

D e c e m b e r 2 0 0 4

E

A d a k I . ( A K )

T s u n a m i

S

e

a

le

v

e

l

( R u s s i a )

S a n d P o i n t ( A K )

D u t c h H a r b o r ( A K )

K o d i a k I . ( A K )

1 2

1 2

1 2

1 2

A t m o s p h e r i c a l l y -i n d u c e d s e i c h e s

North Pacific Ocean

Aleutian and Kuril Islands

Pacific coast of Canada



Recorded tsunami wave

heights along the coast

of South America

Indian Ocean

(Sumatra) tsunami of

December 26, 2004



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…]



Northern group

of stations

Reconstructedsource functions

0.1)(

)(ˆ

)()(

)(S

)()( 21

0

0

0

background

observed+≈

+==

−

ω ω

ω

ω ω

ω

ω ω E A

S

S E S R



Southern group

of stations

Reconstructedsource functions



Averaged source function

While individual tsunami

spectra are significantlydifferent for different

stations, the

reconstructed “source

function” is supposed to

be independent of localtopographic 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.



Reconstructed source functions

based on Canadian records (BC coast)



Wavelet plots of the 2004 Indian Ocean tsunami (1)

Time:

25/12 18h

– 28/12 18h

Periods:

2.5h – 0.20h



Wavelet plots of the 2004 Indian Ocean tsunami (2)

Time:

25/12 18h

– 28/12 18h

Periods:

2.5h – 0.20h



Wavelet analysis of the

Indian Ocean records

Time:

25/12 12h – 28/12 12h

Periods: 2.5h – 0.20h

(Cocos1: 1.67h – 0.13h)



Conclusions:Conclusions:

1.1. The 2004 Sumatra tsunami was the first global-The 2004 Sumatra tsunami was the first global-scale tsunami in the “instrumental era” and it wasscale tsunami in the “instrumental era” and it was

observed throughout the World Ocean, includingobserved throughout the World Ocean, including

the North Pacific, North Atlantic and Antarcticthe North Pacific, North Atlantic and Antarctic

Oceans.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).



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 bylong 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.



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 veryconsistent and almost independent of local

topographic effects and is apparently related to the

spectral characteristics of the source.

Kumar Simant

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