Microsoft Word - 29 Sep 2009 Samoa Tsunami_Rev

The mission of the JRC-IPSC is to provide research results and to support EU policy-makers in
their effort towards global security and towards protection of European citizens from accidents,
deliberate attacks, fraud and illegal actions against EU policies.

European Commission
Joint Research Centre
Institute for the Protection and Security of the Citizen

Contact information: Alessandro Annunziato
Address: JRC, Ispra
E-mail:

alessandro.annunziato@jrc.it

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EUR XXXXX LL
ISBN X-XXXX-XXXX-X
ISSN 1018-5593
DOI XXXXX

Luxembourg: Office for Official Publications of the European Communities

© European Communities, 2009

Reproduction is authorised provided the source is acknowledged

Table of Contents

Introduction ................................................................................................................................................. 7

Description of the tsunami event ................................................................................................................. 9

2.1

Tectonic Summary ................................................................................................................................. 9

2.2

Available INͲSITU measurements ......................................................................................................... 11

2.3

Impact of the tsunami .......................................................................................................................... 14

2.4

GDACS Response ................................................................................................................................. 15

2.5

Automatic reports for this earthquake................................................................................................. 15

2.6

GDACS Virtual OSOCC .......................................................................................................................... 16

Analysis and methodology ......................................................................................................................... 17

3.1

Fault mechanism ................................................................................................................................. 18

3.1.1

NearͲreal time calculations ......................................................................................................... 18

3.1.2

Post event calculations ............................................................................................................... 18

3.2

Hydraulic initial conditions ................................................................................................................... 20

3.3

travel time ........................................................................................................................................... 21

RESULTS OF NearͲreal time CALCULATIONS ............................................................................................... 23

Post Event Simulations ............................................................................................................................... 25

5.1

Comparison with DART measurementS ............................................................................................... 27

5.2

COMPARISON WITH TIDAL MEASUREMENTS ....................................................................................... 33

5.2.1

Western Samoa .......................................................................................................................... 33

5.3

Pago Pago ............................................................................................................................................ 36

5.4

Niuatoputu, Tonga ............................................................................................................................... 41

5.5

OfuͲTau, American Samoa ................................................................................................................... 44

Inundation calculations for selected areas ................................................................................................. 46

Conclusions ................................................................................................................................................ 49

References ................................................................................................................................................. 50

Appendix A – PTWS Bulletins ..................................................................................................................... 51

9.1

TSUNAMI BULLETIN NUMBER 001 ....................................................................................................... 51

9.2

TSUNAMI BULLETIN NUMBER 002 ....................................................................................................... 54

9.3

TSUNAMI BULLETIN NUMBER 003 ....................................................................................................... 57

9.4

TSUNAMI BULLETIN NUMBER 004 ....................................................................................................... 60

Executive Summary

On 29 September 2009 at 17:48:11 UTC a large earthquake of magnitude 8 struck offͲshore of the Samoa Islands and
generated a large tsunami that destroyed several villages and caused more than 160 fatalities.

This report first presents the characteristics of the earthquake and discusses the best estimations for the fault
parameters. These are necessary input data for the hydrodynamic tsunami calculations. Then, a comparison between the
nearͲreal time systems and the postͲevent calculations is performed, with an analysis of the observed differences
compared with observed tidal measurements. Coarse, detailed and very detailed calculations are presented in order to
identify areas of maximum damage.

Over time, seismological institutions published more accurate data, which triggered new impact evaluations. The first
data was received from the Pacific Tsunami Warning Centre (through the USGS/NEIC information feeds (see Appendix A).
This was 16 minutes after the event, but had an underestimated magnitude, causing a green alert. The first Orange alert
was generated based on information from NOAA, received 20 minutes after the event (again through the NEIC feeds).
Later, magnitude was revised upwards and depth downwards, increasing the alert level to Red (with a gridͲbased tsunami
wave height of 4.01m).

Several inͲsitu sensors are located in the area, but not all were functional during the event. The main ones against which
we will compare the calculations are 2 bottom pressure measurements (DART) and 2 tidal measurements located in Apia
(maximum height 0.7m) and Pago Pago (maximum measured height 1.6m).

The nearͲreal time calculations were automatically initialized with an initial maximum height of 3.16m. The maximum
height indicated in the calculations is 3.8m in Fagamalo and Poloa and 3.1m in Fagasa all in American Samoa, in the island
of PagoͲPago. The nearͲreal time calculation correctly identified the severity of the event and indicated which islands
were mostly affected.

Post event calculations were performed in order to better represent the event and identify more in detail the affected
locations. It was found that the most damaged locations are the Southern section of Western Samoa islands, Pago Pago
and Niuatoputu islands. This is in agreement with the locations indicated by the Red Cross as most affected.

It was also attempted to evaluate the inundation using a more detailed model and the results are encouraging. The
flooded areas for which we had confirmation from satellite images were in effect modelled as flooded.

INTRODUCTION

On 29 September 2009 at 17:48:11 UTC a large earthquake of magnitude 8 struck offͲshore of the Samoa Islands and

generated a large tsunami that destroyed several villages and caused more than 160 fatalities.

The Joint Research Centre of the European Commission has developed an automatic tsunami calculation system that is

invoked by the Global Disasters Alert and Coordination System (GDACS) when needed. During the Samoa event the

system was repeatedly activated when increasingly accurate information on the earthquake became available.

Calculations are triggered when new parametric solutions (magnitude, depth and location) are published by seismological

organizations (e.g. USGS, EMSC, GEOFON or others). The automatic system successfully identified a risk of a large event

for the Samoa islands and its calculations were available online in less than 20 minutes after the earthquake event.

The day after the event, USGS published

the Global CMT Project Moment Tensor Solution for the earthquake and a day

later the Finite Fault Model solution. The latter represents the best solution for the reconstruction of the initial fault form.

This report shows the initial calculations, automatically performed by the JRC Tsunami Calculation System and the

calculations performed in the days after the event, when the Finite Fault Model solution became available. Calculation

accuracy is evaluated by quantifying the discrepancy between sea level measurements and the initial (nearͲreal time)

calculations, and subsequent more detailed calculations.

It is important, however, to underline that there are several types of calculations and each of them has its own merit and

needs.

x NearͲreal time calculations

o These are performed very quickly after an event and can only use the information available 15Ͳ20 min

after the event. The fault mechanism is not very well known (conservative assumptions must be done)

and the position or the depth is not precise at the beginning.

o The nodalisation is rather coarse (cell size between 2 and 8 km) to shorten the calculation time.
o The objective of these calculation is the identification of the affected locations without pretending to

exactly predict the height in all the locations.

x Grid scenario calculations

o These are performed before an event for all likely tsunami scenarios. General assumptions on the fault

mechanism must be done (conservative).

o The nodalisation is rather coarse (cell size between 2 and 8 km) to shorten the calculation time a limit

the data volume.

o The objective of these calculation is the same as the near realͲtime calculations, but with even faster

response times: calculations are not performed but alert systems can look up the scenario results in a

database.

x Post event calculations

o They are performed one or two days after an event when more information is available on the fault

mechanism.

o The nodalisation becomes more detailed (cell size between 200 and 900m) in order to accurately

estimate the results.

o The objective is to identify more precisely the locations and try to estimate the runͲup height and the

potential damage in the various coastal areas. In case an impact assessment is requested, inundation

calculations are performed. In this case it is necessary to increase the detail level by reducing the cell

size, i.e. down to 10Ͳ20m. The results are affected by the precision of the available topography and

bathymetry, buildings, infrastructures, etc.

x Risk assessment and risk management calculations

o These are performed before an event and are based on historical events.

http://earthquake.usgs.gov/eqcenter/eqinthenews/2009/us2009mdbi/#scitech

o These calculations are aimed at preparing evacuation plans in case of tsunami. They are very much site

specific and in general it is necessary to perform very detailed calculations reducing the cell size down

to 5Ͳ20m. Correspondingly also the bathymetry has to be specified with extreme detail which is not

available worldwide.

The GDACS system is triggering

nearͲreal time calculations, which provide the appropriate information for its alerting

functions. However, for this tsunami in Samoa we also performed

post event calculations in order to better understand

the phenomena, identify the locations affected and obtain feedback to improve the nearͲreal time calculations, if

possible.

The analysis is conducted using 3 numerical codes: the SWANͲJRC code, which is the basis for the overall tsunami grid

scenario calculations in support of GDACS; the HyFlux2 code which solves the equations with a different numerical

method which is particularly relevant for inundation calculations; the TUNAMI2 code, by Prof. Imamura, to have another

reference. The calculations are also compared with the results of the NOAA unit source results as far as regards nearͲreal

time calculations.

DESCRIPTION OF THE TSUNAMI EVENT

On 29/09/2009 17:48:15 UTC an earthquake of magnitude 8 and depth 18km triggered a tsunami with calculated
maximum wave height of 2.2m near the coast of Samoa Islands Region. Media report local waves of up to 7m, and
casualty tolls reaching 160 deaths

Widespread damage was reported to infrastructure at Pago Pago, American Samoa, and in many parts of Samoa and on
Niuatoputapu, Tonga. The following peakͲtoͲthrough wave heights were recorded: 3.14m at Pago Pago (American
Samoa); 1.40m at Apia (Samoa); 0.47m at Rarotonga and 8 cm at Penrhyn (Cook Islands); 14 cm at Nuku`alofa (Tonga) and
11 cm at Papeete (French Polynesia).

According to the UNͲOCHA Situation report #6 (6 Oct 2009) the major relief effort is focused in two locations: (1) the
southern coast of Upolu (Western Samoa), where the most significant damage was sustained, and (2) the small island of
Manono, where infrastructure and water supply were damaged.

Assessments by the Samoan Red Cross indicate that 40

villages have been affected along the southͲeastern coast, with 20 villages completely destroyed by tsunami waves.
Approximately 3,200 people (640 families) have been left homeless. People are living in makeshift shelters in their
gardens on higher grounds and with host families. The Government of Samoa estimated the cost of damage to
infrastructure, public and private properties at around Samoan Tala 380 million (approximately €100 million).

2.1

TECTONIC SUMMARY

In order to perform correct tsunami simulation of the 29 September 2009 Samoa earthquake, it is necessary to take into

account the tectonic setting and seismicity of Samoa and surrounded area. It is important to analyse the entire scenario

of effects by carrying out earthquake parameters in the form of epicentre, depth, fault length, fault width, slip

distribution and fault mechanism.

The earthquake occurred as part of a clustering of a major seismic activity in the north of Tonga Trench (TT) which may

have reflected a reactivation of all major plate boundaries in the region (Error! Reference source not found.). The Tonga

Trench is located in the Pacific Ocean and is 10.882 meters (35.702 ft) deep at its deepest point, known as the Horizon

Deep. It is a deep canyon on the edge of the Pacific Plate. The region has a complex tectonic regime and very high level of

seismic activity related to the compressional motion between Pacific and Australian Plate (Error! Reference source not

found.). The Pacific tectonic plate dives beneath the Australian plate at a rate of almost a centimetre a year, making the

area one of the most active earthquake regions in the world. The earthquakes occur within the Pacific plate on both sides

of the trench. The trench and associated faults are forming as the Pacific Plate moves westward, sinking beneath a

complex series of smaller plates on the edge of the Australian Plate. There have been around 30 quakes of magnitude 7.0

or more along this trench since 1900 (

http://earthquake.usgs.gov/regional/neic

). Figure 1 shows the location of the

earthquake in relation to the Samoa islands. The Samoa earthquake occurred on a subtle ridge on the seafloor, called

“outer rise”, near the Tango Trench. Outer rise earthquakes occur when normal faults oceanͲward of the subduction

zone are activated by flexture of the plate as it bends into the subduction. On the basis of currently available fault

mechanism information after the earthquake, it could be inferred the earthquake occurred as a

normal fault rupture on

the outer rise of the Tonga Trench.

Figure 1 ͲDistribution of the historical earthquakes (dots) and epicentre of the 29 September 2009 Samoa earthquake (star).

Figure 2 Ͳ Proposed plate tectonic map for the Tonga region (Pelletier et al., 1998). NHT :New Hebrides Trench; TT: Tonga Trench; NBAT and SBAT :

resp. North and South New Hebrides BackͲArc Troughs; CBAC :Central New Hebrides BackͲArc Compressional zone; ESR, CSR, WSR, NSR and N160R D

resp. East, Central, West, North and N160ºE spreading ridges of the North Fiji basin; ELSC, CLSC, NWLSC and NELSC: resp. East, Central, NorthͲWest

and NorthͲEast Lau Spreading Centres; PR : Peggy ridge; FFZ : Fiji fracture zone; FP : Fiji platform; NC, SC, S, M, E, Ta, Mt, V, T, Nt, Ni and F: resp.New

Caledonia, Santa Cruz, Santo, Malekula, Efate, Tanna, Matthew, Vava’u, Tongatapu, Niuatoputapu, Niuafo’ou and Futuna Islands; VTL: Vitiaz trench

lineament; CKL: Conway–Kandavu lineament; shaded areas indicate subducting ridges and plateaus; DER, LyR, LR and SR : resp. d’Entrecateaux,

Loyalty, Louisville and Samoan Ridges; WTP: West Torres plateau

2.2

AVAILABLE INͲSITU MEASUREMENTS

Several inͲsitu sensors are located in

the area, but not all were functional

during the event. The main ones

against which we will compare the

calculations are:

DART measurements:

x 51425
x 51426

Tidal level measurements:

x Apia
x Pago Pago

These were the closest inͲsitu

measurement points.

According to the tsunami travel time

both DART buoys should have been

reached in about 1h and the tidal

measurements between 15 and 25

minutes from the event.

A negative initial wave is recorded by

3 sensors (51425, Apia and Pago

Pago), which is consistent with the

proposed fault mechanism (see

chapter 3.1.2). The sensor on the

North – NorthͲEast side shows a

negative section, while 51426 shows

an initial positive section which could indicate that a higher positive section should be present in the Southern part of the

fault.

There are several other measurement points available in the Pacific Ocean that can be useful to estimate the arrival time,

but the ones indicated are the most relevant to analyse in greater detail the tsunami phenomenon.

51425

51426

Pago-Pago

Apia

2.3

IMPACT OF THE TSUNAMI

The table below has been compiled by NOAA and included in the NGDC database. Many more points will be available in

the future. For the moment most of the measures are based on tidal measurements. The last 4 columns are related to

calculations described in the following sections.

Country Location

Lat.

Lon.

Distance

(km)

Height

(m)

Deaths

Estim.

Time

Calcul.

Time

Calc.

Height (m)

Cell size

(min)

Tonga

Niuatoputapu

Ͳ15.95

Ͳ173.75

183

0:22

8.8

0.1

Usa Territory

Pago Pago

Ͳ14.283

Ͳ170.68

208

0:11

2.16

20’

0:22

3.0

0.1

Samoa

Upolu

Ͳ13.817

Ͳ171.75

197

0:21

0.78

27’

0:27

0.76

0.1

Samoa

Apia

Ͳ13.817 Ͳ171.75 197

0:44

0.70

110

0:27

0.76 0.1

Tonga

Nukualofa
(Nuku'alofa)

Ͳ21.133

Ͳ175.17

700

0:59

0.15

0:49

0.2

1.0

Cook Islands

Rarotonga Ͳ21.18

Ͳ159.77

1442

1:48

0.62

1:41

0.1

4.0

Cook Islands

Penryhn

Ͳ8.59

Ͳ158.07

1710

2:30

0.09

2:12

0.03

4.0

Fiji

Lautoka Ͳ17.6

177.433

1139

3:09

0.09

3:09

<0.01

4.0

French Pol.

Papeete,
Tahiti

Ͳ17.533

Ͳ149.57

2410

3:12

0.15

3:22

0.06

4.0

Kiribati

Christmas Island

1.983

Ͳ157.47

2529

3:24

0.17

3:31

4.0

Vanuatu

Luganville

Ͳ15.515

167.188

2219

4:08

0.17

3h 56’

3:55

4.0

New Zealand

North Cape

4:24

0.23

4:49

4.0

New Zealand

Owenga

Ͳ44.017

138.633

5598

4:26

0.32

4:45

4.0

Table 1Ͳ List of runͲup locations from NGDC Database (http://www.ngdc.noaa.gov/nndc/struts/)

The figure above reports the preͲ and postͲtsunami image of Fagasa Bay, on the Pago Pago Island. While the tide is low in

the postͲimage, some damage among the houses can be seen where the tsunami ran up the land.

2.4

GDACS RESPONSE

The Global Disaster Alert and Coordination System aims at alerting the international humanitarian response community

for disaster that will require international response. GDACS consists of an automatic alerting system (sending SMS, email

and fax alerts to around 10000 users) and a restricted website for professional responders (the Virtual OSOCC).

2.5

AUTOMATIC REPORTS FOR THIS EARTHQUAKE

Over time, seismological institutions published more accurate data, which triggered new impact evaluations. The first

data was received from the Pacific Tsunami Warning Centre (through the USGS/NEIC information feeds (see Appendix A).

This was 16 minutes after the event, but had an underestimated magnitude, causing a green alert. The first Orange alert

was generated based on information from NOAA, received 20 minutes after the event (again through the NEIC feeds).

Later, magnitude was revised upwards and depth downwards, increasing the alert level to Red (with a gridͲbased tsunami

wave height of 4.01m).

Alert
level

Estimated

tsunami wave

height (m)

Lat/Lon Magn

itude

(M)

Depth

(km)

Source

Publication Date/Time (UTC)

Delay

0.06

-15.27,

-171.5

7.1

PTWC

9/29/2009 06:04:30 PM

16 min

2.27

-15.4,

-171.6

7.9

NOAA

9/29/2009 06:09:11 PM

20 min

2.27

-15.5538,

-172.1409

7.9

NEIC

9/29/2009 06:14:51 PM

26 min

2.27

-15.42,

-172.21

7.9

EMSC

9/29/2009 06:14:59 PM

26 min

2.27

-15.43,

-172.2

8.1

EMSC

9/29/2009 06:30:02 PM

42 min

4.01

-15.3,

-171.0

8.3

NOAA

9/29/2009 07:05:59 PM

1h17min

2.27

-15.5577,

-172.0726

8.0

NEIC

9/29/2009 07:37:36 PM

1h49min

2.27

-15.3,

-171.0

8.0

NOAA

9/29/2009 10:11:46 PM

3h23min

3.3

-15.559,

-172.0926

8.0

NEIC

9/30/2009 03:15:21 PM

>21h

Table 2 – List of epicentres identified by the GDACS system as they were collected

While these response times are effective for the international community, the systems would have been too slow to alert

some of the most affected areas. The first tsunami waves arrived

in Western Samoa 17 minutes after the earthquake.

Most cities in Western and American Samoa were reached within 20 minutes. The highest waves higher than 7 meters

and generated by local geographic conditions, arrived 30 minutes after the event.

Note that the uncertainty on the earthquake parameters caused an underestimation of wave heights: the maximum wave

height reported by the GDACS system increased from 0.06m to 4.01m (1h17 minutes after the event), while the true

maximum wave heights were up to 7m.

Table 3. Arrival times according to best simulation.

Time Location

Country

Height

(m)

00:17 Poutasi

Samoa

2.7

00:18 Lotofago

Samoa

1.9

00:18 Salailua

Samoa

1.9

00:19 Taputimu American Samoa

3.2

00:19

Leone

American Samoa

3.2

00:19 Vaitogi

American Samoa

3.2

00:19 Vailoatai

American Samoa

3.2

00:19 Iliili

American Samoa

3.2

00:19 Faleniu

American Samoa

3.2

00:19 Falelima

Samoa

1.5

00:19 Amaluia

American Samoa

3.2

00:19 Pavaiai

American Samoa

3.2

In this paragraph, arrival times refer to the time of arrival of the maximum wave height. If the negative part of the wave

arrives first (i.e. retreating water), this is not taken into account.

00:19 Mesepa

American Samoa

3.2

00:19 Futiga

American Samoa

3.2

00:19 Satupaitea Samoa

1.8

00:19 Gautavai

Samoa

1.6

00:19 Faleaseela Samoa

3.5

00:19 Matautu

Samoa

2.9

00:20 Fagasa

American Samoa

3.1

00:20 Aasu

American Samoa

3.1

00:20 Falealupo Samoa

1.2

00:21 Hihifo

Tonga

3.9

00:22 Falehau

Tonga

5.4

00:23 Fagamalo American Samoa

4.7

… …

…

00:30 Alaufau

American Samoa

7.4

00:31 Olosega

American Samoa

5.8

00:31 Lalomoana American

Samoa

5.8

00:32 Tau

American Samoa

7.1

00:32 Faleasau

American Samoa

7.1

2.6

GDACS VIRTUAL OSOCC

The second trigger in the GDACS system is the creation of a new disaster page for an event. For the Samoan tsunami, this

happened on 29 September 2009 at 21:00 UTC (5h after the event). Although the first message in the Virtual OSOCC was

the PTWC Tsunami Bulletin (posted at 18:12 UTC), response information became available only after the creation of the

Samoan disaster page. At that time, the international response community was actively providing information on this

event in the GDACS system, including information on declaration of state of emergency, contact information of local Red

Cross societies, the first OCHA situation report, etc.

ANALYSIS AND METHODOLOGY

The tsunami analysis depends strongly on: a) the initial fault mechanism; b) the hydraulic conditions (e.g. bathymetry cell

size). It is also important to point out that the information available immediately after the event are only epicentre,

magnitude and depth. All these quantities may change significantly due to progressive improvement of the seismological

parameters. The day after the event the fault mechanism was identified and twoͲthree days later USGS published the

finite fault model solution, which is the best characterization of the fault.

The choice of the tsunami source is usually a complicated problem because it requires good knowledge of the earthquake

parameters such as epicentre, depth, fault length, fault width, slip distribution and rupture mechanism. It is assumed that

the tsunami is generated by coseismic displacement of the sea floor. Thus, the initial condition for the expected tsunami

in the region is assumed to coincide with the vertical coseismic displacement of the sea bottom induced by the

earthquake. The initial conditions are one of the major factors that affect the wave propagation and the resulting run up

amplitudes along the shoreline. Different approaches can be used to calculate the initial conditions from the motion of

the fault.

JRC uses three approaches for this purpose. One of them is to evaluate the earth deformation caused by the earthquake

and impose an initial water height proposed by Ward (2001). This approach gives the initial water level increase by using

the empirical relationships between the magnitude of the earthquake and fault length and width. The second one was

developed by Okada (1985). This algorithm calculates the distribution of coseismic uplift and subsidence by using the

epicentre of the earthquake, fault strike, fault dip, fault rake and amount of average displacement on the fault. The third

approach is to use the fault and the direction of slips by separating the fault plane into the subfaults. In order to reveal

the rupture process of the fault with this approach, USGS uses GSN broadband waveforms downloaded from the National

Earthquake Information Center (NEIC) waveform server. They analyses teleseismic broadband P waveforms, broadband

SH wave forms and long period surface waves selected based upon data quality and azimuthal distribution. Waveforms

are first converted to displacement by removing the instrument response and then used to constrain the slip history

based on a finite fault inverse algorithm (Ji et al, 2002). These approaches have been used for the tsunami simulation of

Samoa earthquake in subsequent sections.

The earthquake parameters, fault mechanism solutions and crossͲsection of slip distribution of the fault model – which

are available after the earthquake from the different organizations – are given respectively in Table 4Error! Reference

source not found., Table 5 and Figure 3. The mechanism solutions show an almost normal fault, on a plane striking

roughly parallel to the Tonga Trench axis, with seismic moment of 1.82 × 1028 dyn cm.

Table 4. Earthquake parameters (USGS/NEIC)

Magnitude (Mw)

8.0

Date and Time

29, September 2009 at 17:48:10 UTC

Location

15.509°S, 172.034°W

Depth (km)

Region

Samoa Island Region

In the following we will show the fault mechanisms adopted for the various phases and will compare them.

3.1

FAULT MECHANISM

3.1.1

NEARͲREAL TIME CALCULATIONS

The nearͲreal time calculations were performed using the original JRC fault model which should be considered as an

upper bound or worst case. Several calculations were requested (10) as the epicentre was better identified (see previous

chapter). The final case has been performed with the following parameters:

x L=158 km, W=44 km, Strike=318.4, Form Cosinusoidal, all positive, Hmax=3.16m

The JRC fault model assumes a cosinusoidal shape all positive, in order to maximize the impact. The model assumes a

standards earthquake depth, and applies a scaling factor for the real depth. For a depth of 18km, the depth factor is 0.8.

This, the calculated wave height of 3.16m is reduced to 2.5m. This however was not done for the nearͲreal time

calculations.

Other nearͲreal time calculations during the event were the ones performed by NOAA, with the MOST code; they found

that the best solution for the current fault (as compared with the buoys measurements), was obtained using the unit

sources ntsza34 plus the ntszb34 solution, both multiplied by the factor 3.96. It should be reminded that every NOAA unit

fault source correspond to a 100 km x 50 km fault of elevation 1m (e.g. corresponding to a magnitude of 7.5); thus it is

necessary to multiply for a factor to take into account the different magnitude.

NearͲreal time Calculation GDACS

L=158 km, W=44 km

Strike=318.4

Form Cosinusoidal, all positive, Hmax=3.16 m

MOST calculations

Fault 1 (ntsza34) :L=100 km, W=50 km, Strike=182, Dip=15,

rake=90, depth=13.41 km, slip=3.96 m,

Fault 2 (ntszb34): L=100 km, W=50 km, Strike=182, Dip=9.68,

rake=90, depth=5 km, slip=3.96 m

3.1.2

POST EVENT CALCULATIONS

According to the fault mechanisms published by USGS the day after

the event two possible solutions can be analyzed, the USGS one and

the Harvard one. They differ for the location and mostly for the strike

angle (more vertical in the Harvard one).

The parameters below have been included in the Okada (1985) model

in order to setup the initial deformation.

Table 5. Fault mechanism solutions

Time 17:48:10.57

Lat/Lon

Mag

(Mw) Strike Dip Rake Depth

(km)

USGS Centroid Moment Tensor Solution

Ͳ15.418/Ͳ172.005

8.0

345

Ͳ61

Harvard Global CMT Project Moment Tensor Solution

Ͳ15.195/Ͳ171.9 8.1

Ͳ64 12

Two days after the event the Finite Fault Model solution has been published by USGS

. This solution has been obtained

using GSN broadband waveforms downloaded from the NEIC data server. They analyzed 18 teleseismic broadband P

waveforms, 13 broadband SH waveforms, and 36 long period surface waves selected based upon data quality and

azimuthal distribution. Waveforms were first converted to displacement by removing the instrument response and then

used to constrain the slip history based on a finite fault inverse algorithm (Ji et al, 2002). The hypocenter adopted was the

USGS (Lon.=Ͳ15.60 deg.; Lat.=Ͳ172.30 deg.). The fault planes are defined using the quick moment tensor solution from

Jascha Polet at Cal Poly Ponoma.

The result of this procedure is a series of 432 individual sources of 5 km by 4 km, all at strike 342.45 and dip 57.06. All

fault planes have their own rake and slip. Combined, the sources produce an initial deformation as shown in the previous

figure, which indicates that the best “simple” solution is the one proposed by CMT USGS.

In order to evaluate the effect of each solution on the wave height results it is necessary to run simulations for the various

source solutions. It may be anticipated however that, differently from the nearͲreal time calculation initial condition, all

the solutions show a negative section on the NorthͲEast side.

In the following, most of the calculations have been performed using as initial conditions the Finite Fault model because it

is considered to be the best one, as confirmed by sea level measurements.

Table 6. Different sources for postͲevent calculations. The best “simple” solution is the one proposed by CMT USGS.

USGS CMT

L=158 km, W=44 km

Strike=345, Dip=46, Rake=Ͳ61,

Depth=Ͳ10 km, Slip=3.5 m

Harvard CMT

L=158 km, W=44 km

Strike=7, Dip=71, Rake=Ͳ64,

Depth=Ͳ12 km, Slip=3.5 m

FINITE FAULT MODEL

USGS Finite Fault model

Strike=342.45, Dip=57.06

Rake=variable

Height, see figure on the right

FINITE FAULT MODEL, detail

http://earthquake.usgs.gov/eqcenter/eqinthenews/2009/us2009mdbi/finite_fault.php

RESULTS OF NEARͲREAL TIME CALCULATIONS

In this section only the last performed simulation (the last row in Table 2) is compared. However, all the results of the

other simulations are available online in the GDACS report page.

Figure 10 Ͳ NearͲreal time calculation of the Samoa event: on the left the maximum calculated

height, on the right the list of identified locations and their height

The system was initialized with an initial maximum height of 3.16m. The maximum height indicated in the calculations is

3.8m in Fagamalo and Poloa and 3.1m in Fagasa, all in the island of PagoͲPago (American Samoa Islands). This calculation,

performed with 2.64 min grid size bathymetry was not able to identify the small island where Niuatoputapu Village is

located but a very high energy above that island is shown.

The comparison with the DART shows that the calculation anticipates the

signal on the DART by 5 min and the height is overestimated, while it is very

close in height for the signal in Pago Pago. Nevertheless, the initial negative

wave is not predicted. The reason is in the oversimplified initial condition

which does not allow for an initial negative wave. As explained before, the

JRC fault model assumes an all positive cosinusoidal shape in order to

calculate a worst case scenario for early warning.

While the nearͲreal time calculations are performed, the users could access

the grid preͲcalculations, which should be seen as a preview of the nearͲreal

time calculations. The grid points corresponding to the preͲcalculated

scenarios are represented in the figure on the right. The white points

represent the available scenario epicentres, the blue points are the ones that were invoked by the JRC tsunami system as

being the ones closest to the epicentres identified by the seismological organizations.

POST EVENT SIMULATIONS

The following calculations were performed in the days after the event.

Calc.

Latitude Limits

Longitude Limits

Cell size
(min / km)

Cells
(ncols x nrows)

Time

Input from
calc.

Pacific wide calculation
1

Pacific

Ͳ60

+60

Ͳ240

Ͳ66

4 / 7.4

2614x1804

14 h

Regional calculations

NearͲreal time calculation

Ͳ29.8

Ͳ2.4

Ͳ185.2 Ͳ158.8

2.64

/ 4.8

600x600

Tonga/Samoa

Ͳ23

Ͳ9

Ͳ178

Ͳ167

1 / 1.8

660x840

2 h

Samoa

Ͳ17.5

Ͳ12

Ͳ174

Ͳ169

0.5 / 0.9

542x392

2 h

Detailed local calculations

Western Samoa

Ͳ14.3

Ͳ13.3

Ͳ173

Ͳ171

0.1 / 0.18

1200x600

1 h

Pago Pago

Ͳ14.65

Ͳ14

Ͳ171.1

Ͳ170.2

0.1 / 0.18

540x390

1 h

Niuatoputu, Tonga

Ͳ16.45

Ͳ15.45

Ͳ173.99

Ͳ173.23

0.1 / 0.18

456x600

1 h

Ofu Tau

Ͳ13.9

Ͳ13.3

Ͳ170.1

Ͳ169.1

0.1 / 0.18

604x380

Inundation calculations

Pago Pago

Ͳ14.412

Ͳ14.972

Ͳ170.972

Ͳ170.4515

1 / 30

1874x864

Pago Pago and Fagasa Bay

Ͳ14.3092 Ͳ14.2749

Ͳ170.7317 Ͳ170.6516

0.166 / 5

1728x740

Regional calculations are performed in order to have a quick estimate of the impact of the tsunami. Detailed and more

local calculations are needed in order to correctly analyze the local behaviour and estimate the height in specified

locations, previously identified by regional calculations as most affected. The detailed calculations are performed with

initial and boundary conditions obtained by coarser simulations, as indicated in the last column of the table above.

It should be noted that the nearͲreal time system only performs calculations of the type 2. The reason for performing the

more and more detailed calculations in subsequent steps, with smaller window and cell size, is that the CPU time

necessary for a calculation increases as a cubic function of the cell size reduction, i.e., if the cell size is halved and the

window remains the same, the CPU time becomes 8 times higher. It is not foreseen for the moment to perform very

detailed calculations in nearͲreal time or with the preͲcalculated grid. The detailed calculations are performed on a caseͲ

byͲcase basis after specific important events, such as this one.

The calculations have been performed with the JRC calculation system powered by different hydraulic models: SWAN,

HyFlux2 and TUNAMI (only 1 min grid size calculation, calc. 3 in above table).

Figure 13. Calculations domain for the Pacific basin

4 min

5.1

COMPARISON WITH DART MEASUREMENTS

Three DART sensors are available: 51426, 51426, 54401. For the comparison of the DART measurements we used the 1

min calculations (calc. 3 in above table).

Figure 15. Location of DART measurement 51425

Figure 16. Location of DART measurement 51426

DART sensor 55425, located at latitude Ͳ9.49 and longitude Ͳ176.24, is located North of the fault. The comparison with the

measurements (Figure 17 for SWAN and Figure 18 for HyFlux2) shows that the initial sea level drop is correctly

reproduced at 1h.

Also the maximum height is well reproduced. In the case of SWANͲJRC the trend is more oscillatory rather than with

HyFlux2 but the peak height of 2.5 cm is well identified.

In the case of NOAA (Figure 19) the initial peak is not negative because the initial NOAA fault shows a positive side on

north east. However the maximum peak is well reproduced despite the fact that this is a 4 min simulation.

The TUNAMI simulation (Figure 20) shows results very similar to the SWAN code.

The comparison with DART sensor 51426 (Figure 21 to Figure 24) shows that the initial peak is better reproduced in the

NOAA simulation while in the SWAN, Hyflux2 and Tunami simulations, all initialized with the finite fault model the initial

peak is negative.

However it should be noted that both SWANͲJRC, Hyflux2 and TUNAMI reproduce well the oscillations at 1.6 h, which are

caused by reflection waves coming from the lower bathymetry section and from the islands of PagoͲPago.

These oscillations are not present in the NOAA calculation, which had a lower resolution bathymetry (4 min instead of the

1 min grid size bathymetry).

51425

51426

54401

5.2

COMPARISON WITH TIDAL MEASUREMENTS

Tidal measurements are generally located very close to the coast or even within ports. Therefore it is necessary to adopt

very detailed cells to be able to specify the bathymetry, the shoreline and the possible runͲup topography. The precision

of such information’s’ will strongly influence the simulation accuracy, and the capability of the code to reproduce the real

phenomena.

If we use a rather coarse simulation (such as the one available with nearͲreal time calculations) the prediction cannot be

accurate, but it can still give qualitative correct information.

We decided to analyze in detail 4 areas which showed the highest sea level in the coarser results:

x Western Samoa

x Pago Pago, American Samoa

x Niuatoputu, Tonga

x OfuͲTau, American Samoa

The simulations are performed adopting a 0.1 min grid size bathymetry.

5.2.1

WESTERN SAMOA

Western Samoa Island has been one of the most

affected islands in the archipelago with more than

100 fatalities in the area of Apia.

According to the calculations the greatest wave

occurred in the Southern part of the two islands.

There is only one measurement point on the

island, in the location Apia. Here a maximum of

0.7m or 1.4 from crest to trough was measured.

The calculation correctly predicts a maximum

level between 0.6 and 0.7 on the Northern part of

the island but about 3.1m in Matautu, on the

Southern part of the island.

The figure below represents the behaviour of the sea level during the event. It is possible to note that the northern part

of the islands is reached at a later time with the lower height. The lower part of the islands show heights between 1.3 and

3.8m. The small island of Manono shows a maximum height of 1m but according to Red Cross this is one of the most

affected locations. Probably even a more detailed simulation would be necessary there.

5.3

PAGO PAGO

Waterfront in Pago Pago,

(John Newton / AFP / Getty Images)

Pago Pago was reached by the negative wave about 15 minutes after the event. Local witnesses indicated a water

recession

and then a subsequent increase. According to our calculations the negative section lasted about 7Ͳ8 minutes

before the positive wave arrived.

The comparison with the available measurement is extremely good. The water level initially decreases by 3m and then

rises of almost the same value. However, it should be noted that the best bathymetry available is 30” (i.e. 1 km) , which

was interpolated to 200m to perform these calculations. One can note a slight anticipation of the negative wave, but the

real measurement point is within a bay that is not represented by the 30” grid size bathymetry.

The HyFlux2 calculation shows a behaviour similar to SWANͲJRC, with a slightly higher maximum value for the height. In

the figures we also included the NOAA simulation in order to show that – contrary to the tidal measurement – the initial

simulated disturbance is positive due to the type of fault adopted. This is only a qualitative comparison, knowing that for

any numerical models the simulation accuracy is very poor near the coast when the grid size bathymetry is coarse.

… He told me the water receded and then started to rise. It rose to the top of the seawall where the mgmt parks their

cars….

INUNDATION CALCULATIONS FOR SELECTED AREAS

In order to exploit the capabilities of the HyFlux2 in simulating inundation processes, an attempt was made to analyse a

location for which we found a postͲdisaster satellite image which can give an idea of the Tsunami wave runͲup.

For this type of calculation, extremely detailed maps on bathymetry and topography are required. We found a 5m grid

size bathymetry that was used for the calculations. Eventually a nautical map such the one below, for the Pago Pago bay,

could be digitized in order to produce even a more detailed bathymetry and topography close to the shoreline bay.

The relevant information to simulate the runͲup processes are a) the bathymetry b) the shoreline and c) the topography.

In the Pago Pago bay a bathymetry of 5m grid size resolution has been found in the web (see

http://dusk.geo.orst.edu/djl/samoa/#gmt

). Outside the bay the SRTM 30” grid size (~ 900m) bathymetry is used: such

information is very poor for distance to the coast lower than half pixel size, i.e. 450m. For topography, the most accurate

data are the SRTM 1” data, available for Pago Pago Island (because part of the US territory; for the rest of the world the

SRTM 3” data are available). A 200m buffer containing the bathymetry, extrapolated from the shoreline identified by the

SRTM 1” data is included. For the inundation simulation a raster map with combined bathymetry and topography is

required (see Figure 42). Missing information between these sources (black pixels in the figure) are covered by an inverse

distance interpolation.

Figure 42. Combination of the available and extrapolated DEM data

Figure 44 – Comparison of the calculated inundation with the extent deduced from satellite images from Digital Globe

The comparison of the calculated inundation extent with the one roughly identified from two satellite images by Digital

Globe found on the internet, indicates that the real inundation was wider than calculated one. However it should be

noted that: a) these are very preliminary results that needs to be better analysed; b) the bathymetry/topography adopted

is obtained from different sources with different accuracy and is strongly affected by the interpolation/extrapolation

models adopted; c) some difficulties on georeferencing the images and the calculation results with the Google earth map

are evident in the figure

Nevertheless, the Hyflux2 code was able to simulate the inundation in these two inundated areas. In this particular

simulation, it is evident that other areas appear flooded, for which we do not have images which can confirm the

simulation.

CONCLUSIONS

The report highlights the characteristics and the impact of the tsunami occurred in Samoa on 29 September 2009. The
report describes the event, the available measurements and the seismological situation of the area.

It was shown that the nearͲreal time calculations in the GDACS system were able to give a correct preliminary estimate of
the dimension of the event, even if the incoming new evaluations of the epicentre location and magnitude from the
seismological organizations generated different expected impact from 6 cm to 4m with the last evaluations, performed 1h
after the event.

In order to assess the impact and draw a more detailed situation map finer calculations were performed after the event
and it was possible to identify the most affected areas. The comparison of the calculations with the few available
measurements indicated an accurate estimate. These are the Southern sections of Western Samoa islands, Pago Pago
and Niuatoputu islands.

It was also attempted to evaluate the inundation using a detailed model and the results are encouraging. The flooded
areas for which we had satellite images were in effect flooded. The extent of the flood was slightly underestimated but
the detail and accuracy of the used DEM is probably not sufficient for this level of comparison.

REFERENCES

Annunziato, A. 2007 . The Tsunami Assessment Modelling System by the Joint Research Centre, Science of Tsunami
Hazards, Volume 26, N. 2 (2007)

Franchello, G., 2008. Modelling shallow water flows by a High Resolution Riemann Solver, EUR 23307 EN Ͳ 2008, ISSN
1018Ͳ5593.
http://bookshop.europa.eu/eubookshop/download.action?fileName=LBNA23307ENC_002.pdf&eubphfUid=627660&cata
logNbr=LBͲNAͲ23307ͲENͲC

Franchello, G., 2009, Shoreline tracking and implicit source terms for a well balanced inundation model. Int. Journal for
Numerical Methods in Fluids, in press
http://www3.interscience.wiley.com/journal/122528271/abstract

Okada, Y. 1985. Surface deformation due to shear and tensile faults in a halfͲspace. Bulletin of the Seismological Society
of America. 75. 1135–1154.

Ward, S .N., 2002. Tsunamis, Encyclopedia of Physical Science and Technology, Vol. 17, pp. 175–191, ed. Meyers, R.A.,
Academic Press.

Pelletier, B., Calmant, S., and Pillet, R., 1998. Current tectonics of the Tonga–New Hebrides region, Earth and Planetary
Science Letters 164, 263–276

APPENDIX A – PTWS BULLETINS

9.1

TSUNAMI BULLETIN NUMBER 001

PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS

ISSUED AT 1804Z 29 SEP 2009

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC

OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...

WASHINGTON...OREGON AND CALIFORNIA.

... A TSUNAMI WARNING AND WATCH ARE IN EFFECT ...

A TSUNAMI WARNING IS IN EFFECT FOR

AMERICAN SAMOA / SAMOA / NIUE / WALLIS-FUTUNA / TOKELAU /

COOK ISLANDS / TONGA / TUVALU / KIRIBATI / KERMADEC IS / FIJI /

HOWLAND-BAKER / JARVIS IS. / NEW ZEALAND / FR. POLYNESIA /

PALMYRA IS.

A TSUNAMI WATCH IS IN EFFECT FOR

VANUATU / NAURU / MARSHALL IS. / SOLOMON IS. / JOHNSTON IS. /

NEW CALEDONIA / KOSRAE / PAPUA NEW GUINEA / HAWAII / POHNPEI /

WAKE IS. / PITCAIRN / MIDWAY IS.

FOR ALL OTHER AREAS COVERED BY THIS BULLETIN... IT IS FOR

INFORMATION ONLY AT THIS TIME.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY

NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE

DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND

ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 1748Z 29 SEP 2009

COORDINATES - 15.3 SOUTH 171.0 WEST

DEPTH - SHALLOWER THAN 100 KM

LOCATION - SAMOA ISLANDS REGION

MAGNITUDE - 7.9

EVALUATION

IT IS NOT KNOWN THAT A TSUNAMI WAS GENERATED. THIS WARNING IS

BASED ONLY ON THE EARTHQUAKE EVALUATION. AN EARTHQUAKE OF THIS

SIZE HAS THE POTENTIAL TO GENERATE A DESTRUCTIVE TSUNAMI THAT CAN

STRIKE COASTLINES NEAR THE EPICENTER WITHIN MINUTES AND MORE

DISTANT COASTLINES WITHIN HOURS. AUTHORITIES SHOULD TAKE

APPROPRIATE ACTION IN RESPONSE TO THIS POSSIBILITY. THIS CENTER

WILL MONITOR SEA LEVEL DATA FROM GAUGES NEAR THE EARTHQUAKE TO

DETERMINE IF A TSUNAMI WAS GENERATED AND ESTIMATE THE SEVERITY OF

THE THREAT.

ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES AT FORECAST POINTS

WITHIN THE WARNING AND WATCH AREAS ARE GIVEN BELOW. ACTUAL

ARRIVAL TIMES MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE

LARGEST. A TSUNAMI IS A SERIES OF WAVES AND THE TIME BETWEEN

SUCCESSIVE WAVES CAN BE FIVE MINUTES TO ONE HOUR.

LOCATION FORECAST POINT COORDINATES ARRIVAL TIME

-------------------------------- ------------ ------------

AMERICAN SAMOA PAGO PAGO 14.3S 170.7W 1759Z 29 SEP

SAMOA APIA 13.8S 171.8W 1810Z 29 SEP

NIUE NIUE IS. 19.0S 170.0W 1822Z 29 SEP

WALLIS-FUTUNA WALLIS IS. 13.2S 176.2W 1835Z 29 SEP

TOKELAU NUKUNONU IS. 9.2S 171.8W 1844Z 29 SEP

COOK ISLANDS PUKAPUKA IS. 10.8S 165.9W 1846Z 29 SEP

RAROTONGA 21.2S 159.8W 1929Z 29 SEP

PENRYN IS. 8.9S 157.8W 1954Z 29 SEP

TONGA NUKUALOFA 21.0S 175.2W 1851Z 29 SEP

TUVALU FUNAFUTI IS. 7.9S 178.5E 1932Z 29 SEP

KIRIBATI KANTON IS. 2.8S 171.7W 1935Z 29 SEP

FLINT IS. 11.4S 151.8W 2025Z 29 SEP

MALDEN IS. 3.9S 154.9W 2037Z 29 SEP

CHRISTMAS IS. 2.0N 157.5W 2100Z 29 SEP

TARAWA IS. 1.5N 173.0E 2104Z 29 SEP

KERMADEC IS RAOUL IS. 29.2S 177.9W 1938Z 29 SEP

FIJI SUVA 18.1S 178.4E 2003Z 29 SEP

HOWLAND-BAKER HOWLAND IS. 0.6N 176.6W 2008Z 29 SEP

JARVIS IS. JARVIS IS. 0.4S 160.1W 2028Z 29 SEP

NEW ZEALAND EAST CAPE 37.7S 178.5E 2044Z 29 SEP

GISBORNE 38.7S 178.0E 2100Z 29 SEP

NORTH CAPE 34.4S 173.3E 2112Z 29 SEP

NAPIER 39.5S 176.9E 2140Z 29 SEP

WELLINGTON 41.3S 174.8E 2150Z 29 SEP

AUCKLAND(E) 36.7S 175.0E 2212Z 29 SEP

AUCKLAND(W) 37.1S 174.2E 2239Z 29 SEP

LYTTELTON 43.6S 172.7E 2255Z 29 SEP

NEW PLYMOUTH 39.1S 174.1E 2317Z 29 SEP

NELSON 41.3S 173.3E 2323Z 29 SEP

DUNEDIN 45.9S 170.5E 2331Z 29 SEP

MILFORD SOUND 44.6S 167.9E 2358Z 29 SEP

WESTPORT 41.8S 171.6E 2359Z 29 SEP

FR. POLYNESIA PAPEETE 17.5S 149.6W 2045Z 29 SEP

HIVA OA 10.0S 139.0W 2214Z 29 SEP

RIKITEA 23.1S 135.0W 2247Z 29 SEP

PALMYRA IS. PALMYRA IS. 6.3N 162.4W 2102Z 29 SEP

VANUATU ANATOM IS. 20.2S 169.9E 2117Z 29 SEP

ESPERITU SANTO 15.1S 167.3E 2123Z 29 SEP

NAURU NAURU 0.5S 166.9E 2138Z 29 SEP

MARSHALL IS. MAJURO 7.1N 171.4E 2147Z 29 SEP

KWAJALEIN 8.7N 167.7E 2220Z 29 SEP

ENIWETOK 11.4N 162.3E 2309Z 29 SEP

SOLOMON IS. KIRAKIRA 10.4S 161.9E 2155Z 29 SEP

GHATERE 7.8S 159.2E 2227Z 29 SEP

AUKI 8.8S 160.6E 2244Z 29 SEP

HONIARA 9.3S 160.0E 2244Z 29 SEP

PANGGOE 6.9S 157.2E 2245Z 29 SEP

MUNDA 8.4S 157.2E 2248Z 29 SEP

FALAMAE 7.4S 155.6E 2304Z 29 SEP

JOHNSTON IS. JOHNSTON IS. 16.7N 169.5W 2212Z 29 SEP

NEW CALEDONIA NOUMEA 22.3S 166.5E 2216Z 29 SEP

KOSRAE KOSRAE IS. 5.5N 163.0E 2233Z 29 SEP

PAPUA NEW GUINE KIETA 6.1S 155.6E 2303Z 29 SEP

AMUN 6.0S 154.7E 2323Z 29 SEP

RABAUL 4.2S 152.3E 2349Z 29 SEP

HAWAII NAWILIWILI 22.0N 159.4W 2311Z 29 SEP

HILO 19.7N 155.1W 2314Z 29 SEP

HONOLULU 21.3N 157.9W 2315Z 29 SEP

POHNPEI POHNPEI IS. 7.0N 158.2E 2318Z 29 SEP

WAKE IS. WAKE IS. 19.3N 166.6E 2322Z 29 SEP

9.2

TSUNAMI BULLETIN NUMBER 002

PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS

ISSUED AT 1856Z 29 SEP 2009

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC

OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...

WASHINGTON...OREGON AND CALIFORNIA.

... A TSUNAMI WARNING AND WATCH ARE IN EFFECT ...

A TSUNAMI WARNING IS IN EFFECT FOR

AMERICAN SAMOA / SAMOA / NIUE / WALLIS-FUTUNA / TOKELAU /

COOK ISLANDS / TONGA / TUVALU / KIRIBATI / KERMADEC IS / FIJI /

HOWLAND-BAKER / JARVIS IS. / NEW ZEALAND / FR. POLYNESIA /

PALMYRA IS. / VANUATU / NAURU / MARSHALL IS. / SOLOMON IS.

A TSUNAMI WATCH IS IN EFFECT FOR

JOHNSTON IS. / NEW CALEDONIA / KOSRAE / PAPUA NEW GUINEA /

HAWAII / POHNPEI / WAKE IS. / PITCAIRN / MIDWAY IS. / CHUUK /

AUSTRALIA

FOR ALL OTHER AREAS COVERED BY THIS BULLETIN... IT IS FOR

INFORMATION ONLY AT THIS TIME.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY

NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE

DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND

ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

NOTE THE MAGNITUDE UPGRADE TO 8.3

ORIGIN TIME - 1748Z 29 SEP 2009

COORDINATES - 15.3 SOUTH 171.0 WEST

DEPTH - 33 KM

LOCATION - SAMOA ISLANDS REGION

MAGNITUDE - 8.3

MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY

GAUGE LOCATION LAT LON TIME AMPL PER

------------------- ----- ------ ----- --------------- -----

APIA UPOLU WS 13.8S 171.8W 1832Z 0.70M / 2.3FT 08MIN

PAGO PAGO AS 14.3S 170.7W 1812Z 1.57M / 5.1FT 04MIN

LAT - LATITUDE (N-NORTH, S-SOUTH)

LON - LONGITUDE (E-EAST, W-WEST)

TIME - TIME OF THE MEASUREMENT (Z IS UTC IS GREENWICH TIME)

AMPL - TSUNAMI AMPLITUDE MEASURED RELATIVE TO NORMAL SEA LEVEL.

IT IS ...NOT... CREST-TO-TROUGH WAVE HEIGHT.

VALUES ARE GIVEN IN BOTH METERS(M) AND FEET(FT).

PER - PERIOD OF TIME IN MINUTES(MIN) FROM ONE WAVE TO THE NEXT.

EVALUATION

SEA LEVEL READINGS INDICATE A TSUNAMI WAS GENERATED. IT MAY HAVE

BEEN DESTRUCTIVE ALONG COASTS NEAR THE EARTHQUAKE EPICENTER AND

COULD ALSO BE A THREAT TO MORE DISTANT COASTS. AUTHORITIES SHOULD

TAKE APPROPRIATE ACTION IN RESPONSE TO THIS POSSIBILITY. THIS

CENTER WILL CONTINUE TO MONITOR SEA LEVEL DATA TO DETERMINE THE

EXTENT AND SEVERITY OF THE THREAT.

FOR ALL AREAS - WHEN NO MAJOR WAVES ARE OBSERVED FOR TWO HOURS

AFTER THE ESTIMATED TIME OF ARRIVAL OR DAMAGING WAVES HAVE NOT

OCCURRED FOR AT LEAST TWO HOURS THEN LOCAL AUTHORITIES CAN ASSUME

THE THREAT IS PASSED. DANGER TO BOATS AND COASTAL STRUCTURES CAN

CONTINUE FOR SEVERAL HOURS DUE TO RAPID CURRENTS. AS LOCAL

CONDITIONS CAN CAUSE A WIDE VARIATION IN TSUNAMI WAVE ACTION THE

ALL CLEAR DETERMINATION MUST BE MADE BY LOCAL AUTHORITIES.

ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES AT FORECAST POINTS

WITHIN THE WARNING AND WATCH AREAS ARE GIVEN BELOW. ACTUAL

ARRIVAL TIMES MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE

LARGEST. A TSUNAMI IS A SERIES OF WAVES AND THE TIME BETWEEN

SUCCESSIVE WAVES CAN BE FIVE MINUTES TO ONE HOUR.

LOCATION FORECAST POINT COORDINATES ARRIVAL TIME

-------------------------------- ------------ ------------

AMERICAN SAMOA PAGO PAGO 14.3S 170.7W 1759Z 29 SEP

SAMOA APIA 13.8S 171.8W 1810Z 29 SEP

NIUE NIUE IS. 19.0S 170.0W 1822Z 29 SEP

WALLIS-FUTUNA WALLIS IS. 13.2S 176.2W 1835Z 29 SEP

TOKELAU NUKUNONU IS. 9.2S 171.8W 1844Z 29 SEP

COOK ISLANDS PUKAPUKA IS. 10.8S 165.9W 1846Z 29 SEP

RAROTONGA 21.2S 159.8W 1929Z 29 SEP

PENRYN IS. 8.9S 157.8W 1954Z 29 SEP

TONGA NUKUALOFA 21.0S 175.2W 1851Z 29 SEP

TUVALU FUNAFUTI IS. 7.9S 178.5E 1932Z 29 SEP

KIRIBATI KANTON IS. 2.8S 171.7W 1935Z 29 SEP

FLINT IS. 11.4S 151.8W 2025Z 29 SEP

MALDEN IS. 3.9S 154.9W 2037Z 29 SEP

CHRISTMAS IS. 2.0N 157.5W 2100Z 29 SEP

TARAWA IS. 1.5N 173.0E 2104Z 29 SEP

KERMADEC IS RAOUL IS. 29.2S 177.9W 1938Z 29 SEP

FIJI SUVA 18.1S 178.4E 2003Z 29 SEP

HOWLAND-BAKER HOWLAND IS. 0.6N 176.6W 2008Z 29 SEP

JARVIS IS. JARVIS IS. 0.4S 160.1W 2028Z 29 SEP

NEW ZEALAND EAST CAPE 37.7S 178.5E 2044Z 29 SEP

GISBORNE 38.7S 178.0E 2100Z 29 SEP

NORTH CAPE 34.4S 173.3E 2112Z 29 SEP

NAPIER 39.5S 176.9E 2140Z 29 SEP

WELLINGTON 41.3S 174.8E 2150Z 29 SEP

AUCKLAND(E) 36.7S 175.0E 2212Z 29 SEP

AUCKLAND(W) 37.1S 174.2E 2239Z 29 SEP

LYTTELTON 43.6S 172.7E 2255Z 29 SEP

NEW PLYMOUTH 39.1S 174.1E 2317Z 29 SEP

NELSON 41.3S 173.3E 2323Z 29 SEP

DUNEDIN 45.9S 170.5E 2331Z 29 SEP

MILFORD SOUND 44.6S 167.9E 2358Z 29 SEP

WESTPORT 41.8S 171.6E 2359Z 29 SEP

BLUFF 46.6S 168.3E 0044Z 30 SEP

FR. POLYNESIA PAPEETE 17.5S 149.6W 2045Z 29 SEP

HIVA OA 10.0S 139.0W 2214Z 29 SEP

RIKITEA 23.1S 135.0W 2247Z 29 SEP

PALMYRA IS. PALMYRA IS. 6.3N 162.4W 2102Z 29 SEP

VANUATU ANATOM IS. 20.2S 169.9E 2117Z 29 SEP

ESPERITU SANTO 15.1S 167.3E 2123Z 29 SEP

NAURU NAURU 0.5S 166.9E 2138Z 29 SEP

MARSHALL IS. MAJURO 7.1N 171.4E 2147Z 29 SEP

KWAJALEIN 8.7N 167.7E 2220Z 29 SEP

ENIWETOK 11.4N 162.3E 2309Z 29 SEP

SOLOMON IS. KIRAKIRA 10.4S 161.9E 2155Z 29 SEP

GHATERE 7.8S 159.2E 2227Z 29 SEP

AUKI 8.8S 160.6E 2244Z 29 SEP

HONIARA 9.3S 160.0E 2244Z 29 SEP

PANGGOE 6.9S 157.2E 2245Z 29 SEP

MUNDA 8.4S 157.2E 2248Z 29 SEP

FALAMAE 7.4S 155.6E 2304Z 29 SEP

JOHNSTON IS. JOHNSTON IS. 16.7N 169.5W 2212Z 29 SEP

NEW CALEDONIA NOUMEA 22.3S 166.5E 2216Z 29 SEP

KOSRAE KOSRAE IS. 5.5N 163.0E 2233Z 29 SEP

PAPUA NEW GUINE KIETA 6.1S 155.6E 2303Z 29 SEP

AMUN 6.0S 154.7E 2323Z 29 SEP

RABAUL 4.2S 152.3E 2349Z 29 SEP

LAE 6.8S 147.0E 0015Z 30 SEP

KAVIENG 2.5S 150.7E 0016Z 30 SEP

PORT MORESBY 9.3S 146.9E 0039Z 30 SEP

MADANG 5.2S 145.8E 0041Z 30 SEP

MANUS IS. 2.0S 147.5E 0050Z 30 SEP

HAWAII NAWILIWILI 22.0N 159.4W 2311Z 29 SEP

HILO 19.7N 155.1W 2314Z 29 SEP

HONOLULU 21.3N 157.9W 2315Z 29 SEP

POHNPEI POHNPEI IS. 7.0N 158.2E 2318Z 29 SEP

WAKE IS. WAKE IS. 19.3N 166.6E 2322Z 29 SEP

PITCAIRN PITCAIRN IS. 25.1S 130.1W 2329Z 29 SEP

MIDWAY IS. MIDWAY IS. 28.2N 177.4W 2349Z 29 SEP

CHUUK CHUUK IS. 7.4N 151.8E 0020Z 30 SEP

AUSTRALIA BRISBANE 27.2S 153.3E 0036Z 30 SEP

SYDNEY 33.9S 151.4E 0038Z 30 SEP

BULLETINS WILL BE ISSUED HOURLY OR SOONER IF CONDITIONS WARRANT.

THE TSUNAMI WARNING AND WATCH WILL REMAIN IN EFFECT UNTIL

FURTHER NOTICE.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS

FOR ALASKA...BRITISH COLUMBIA...WASHINGTON...OREGON...CALIFORNIA.

9.3

TSUNAMI BULLETIN NUMBER 003

PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS

ISSUED AT 2022Z 29 SEP 2009

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC

OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...

WASHINGTON...OREGON AND CALIFORNIA.

... A TSUNAMI WARNING AND WATCH ARE IN EFFECT ...

A TSUNAMI WARNING IS IN EFFECT FOR

AMERICAN SAMOA / SAMOA / NIUE / WALLIS-FUTUNA / TOKELAU /

COOK ISLANDS / TONGA / TUVALU / KIRIBATI / KERMADEC IS / FIJI /

HOWLAND-BAKER / JARVIS IS. / NEW ZEALAND / FR. POLYNESIA /

PALMYRA IS. / VANUATU / NAURU / MARSHALL IS. / SOLOMON IS. /

JOHNSTON IS. / NEW CALEDONIA / KOSRAE / PAPUA NEW GUINEA /

POHNPEI / WAKE IS.

A TSUNAMI WATCH IS IN EFFECT FOR

PITCAIRN / MIDWAY IS. / CHUUK / AUSTRALIA / MARCUS IS. /

N. MARIANAS / GUAM / INDONESIA / ANTARCTICA / YAP

FOR ALL OTHER AREAS COVERED BY THIS BULLETIN... IT IS FOR

INFORMATION ONLY AT THIS TIME.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY

NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE

DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND

ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 1748Z 29 SEP 2009

COORDINATES - 15.3 SOUTH 171.0 WEST

DEPTH - 33 KM

LOCATION - SAMOA ISLANDS REGION

MAGNITUDE - 8.3

MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY

GAUGE LOCATION LAT LON TIME AMPL PER

------------------- ----- ------ ----- --------------- -----

RAROTONGA CK 21.2S 159.8W 1951Z 0.47M / 1.5FT 08MIN

APIA UPOLU WS 13.8S 171.8W 1832Z 0.70M / 2.3FT 08MIN

PAGO PAGO AS 14.3S 170.7W 1812Z 1.57M / 5.1FT 04MIN

LAT - LATITUDE (N-NORTH, S-SOUTH)

LON - LONGITUDE (E-EAST, W-WEST)

TIME - TIME OF THE MEASUREMENT (Z IS UTC IS GREENWICH TIME)

AMPL - TSUNAMI AMPLITUDE MEASURED RELATIVE TO NORMAL SEA LEVEL.

IT IS ...NOT... CREST-TO-TROUGH WAVE HEIGHT.

VALUES ARE GIVEN IN BOTH METERS(M) AND FEET(FT).

PER - PERIOD OF TIME IN MINUTES(MIN) FROM ONE WAVE TO THE NEXT.

EVALUATION

SEA LEVEL READINGS INDICATE A TSUNAMI WAS GENERATED. IT MAY HAVE

BEEN DESTRUCTIVE ALONG COASTS NEAR THE EARTHQUAKE EPICENTER AND

COULD ALSO BE A THREAT TO MORE DISTANT COASTS. AUTHORITIES SHOULD

TAKE APPROPRIATE ACTION IN RESPONSE TO THIS POSSIBILITY. THIS

CENTER WILL CONTINUE TO MONITOR SEA LEVEL DATA TO DETERMINE THE

EXTENT AND SEVERITY OF THE THREAT.

FOR ALL AREAS - WHEN NO MAJOR WAVES ARE OBSERVED FOR TWO HOURS

AFTER THE ESTIMATED TIME OF ARRIVAL OR DAMAGING WAVES HAVE NOT

OCCURRED FOR AT LEAST TWO HOURS THEN LOCAL AUTHORITIES CAN ASSUME

THE THREAT IS PASSED. DANGER TO BOATS AND COASTAL STRUCTURES CAN

CONTINUE FOR SEVERAL HOURS DUE TO RAPID CURRENTS. AS LOCAL

CONDITIONS CAN CAUSE A WIDE VARIATION IN TSUNAMI WAVE ACTION THE

ALL CLEAR DETERMINATION MUST BE MADE BY LOCAL AUTHORITIES.

ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES AT FORECAST POINTS

WITHIN THE WARNING AND WATCH AREAS ARE GIVEN BELOW. ACTUAL

ARRIVAL TIMES MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE

LARGEST. A TSUNAMI IS A SERIES OF WAVES AND THE TIME BETWEEN

SUCCESSIVE WAVES CAN BE FIVE MINUTES TO ONE HOUR.

LOCATION FORECAST POINT COORDINATES ARRIVAL TIME

-------------------------------- ------------ ------------

AMERICAN SAMOA PAGO PAGO 14.3S 170.7W 1759Z 29 SEP

SAMOA APIA 13.8S 171.8W 1810Z 29 SEP

NIUE NIUE IS. 19.0S 170.0W 1822Z 29 SEP

WALLIS-FUTUNA WALLIS IS. 13.2S 176.2W 1835Z 29 SEP

TOKELAU NUKUNONU IS. 9.2S 171.8W 1844Z 29 SEP

COOK ISLANDS PUKAPUKA IS. 10.8S 165.9W 1846Z 29 SEP

RAROTONGA 21.2S 159.8W 1929Z 29 SEP

PENRYN IS. 8.9S 157.8W 1954Z 29 SEP

TONGA NUKUALOFA 21.0S 175.2W 1851Z 29 SEP

TUVALU FUNAFUTI IS. 7.9S 178.5E 1932Z 29 SEP

KIRIBATI KANTON IS. 2.8S 171.7W 1935Z 29 SEP

FLINT IS. 11.4S 151.8W 2025Z 29 SEP

MALDEN IS. 3.9S 154.9W 2037Z 29 SEP

CHRISTMAS IS. 2.0N 157.5W 2100Z 29 SEP

TARAWA IS. 1.5N 173.0E 2104Z 29 SEP

KERMADEC IS RAOUL IS. 29.2S 177.9W 1938Z 29 SEP

FIJI SUVA 18.1S 178.4E 2003Z 29 SEP

HOWLAND-BAKER HOWLAND IS. 0.6N 176.6W 2008Z 29 SEP

JARVIS IS. JARVIS IS. 0.4S 160.1W 2028Z 29 SEP

NEW ZEALAND EAST CAPE 37.7S 178.5E 2044Z 29 SEP

GISBORNE 38.7S 178.0E 2100Z 29 SEP

NORTH CAPE 34.4S 173.3E 2112Z 29 SEP

NAPIER 39.5S 176.9E 2140Z 29 SEP

WELLINGTON 41.3S 174.8E 2150Z 29 SEP

AUCKLAND(E) 36.7S 175.0E 2212Z 29 SEP

AUCKLAND(W) 37.1S 174.2E 2239Z 29 SEP

LYTTELTON 43.6S 172.7E 2255Z 29 SEP

NEW PLYMOUTH 39.1S 174.1E 2317Z 29 SEP

NELSON 41.3S 173.3E 2323Z 29 SEP

DUNEDIN 45.9S 170.5E 2331Z 29 SEP

MILFORD SOUND 44.6S 167.9E 2358Z 29 SEP

WESTPORT 41.8S 171.6E 2359Z 29 SEP

BLUFF 46.6S 168.3E 0044Z 30 SEP

FR. POLYNESIA PAPEETE 17.5S 149.6W 2045Z 29 SEP

HIVA OA 10.0S 139.0W 2214Z 29 SEP

RIKITEA 23.1S 135.0W 2247Z 29 SEP

PALMYRA IS. PALMYRA IS. 6.3N 162.4W 2102Z 29 SEP

VANUATU ANATOM IS. 20.2S 169.9E 2117Z 29 SEP

ESPERITU SANTO 15.1S 167.3E 2123Z 29 SEP

NAURU NAURU 0.5S 166.9E 2138Z 29 SEP

MARSHALL IS. MAJURO 7.1N 171.4E 2147Z 29 SEP

KWAJALEIN 8.7N 167.7E 2220Z 29 SEP

ENIWETOK 11.4N 162.3E 2309Z 29 SEP

SOLOMON IS. KIRAKIRA 10.4S 161.9E 2155Z 29 SEP

GHATERE 7.8S 159.2E 2227Z 29 SEP

AUKI 8.8S 160.6E 2244Z 29 SEP

HONIARA 9.3S 160.0E 2244Z 29 SEP

PANGGOE 6.9S 157.2E 2245Z 29 SEP

MUNDA 8.4S 157.2E 2248Z 29 SEP

FALAMAE 7.4S 155.6E 2304Z 29 SEP

JOHNSTON IS. JOHNSTON IS. 16.7N 169.5W 2212Z 29 SEP

NEW CALEDONIA NOUMEA 22.3S 166.5E 2216Z 29 SEP

KOSRAE KOSRAE IS. 5.5N 163.0E 2233Z 29 SEP

PAPUA NEW GUINE KIETA 6.1S 155.6E 2303Z 29 SEP

AMUN 6.0S 154.7E 2323Z 29 SEP

RABAUL 4.2S 152.3E 2349Z 29 SEP

LAE 6.8S 147.0E 0015Z 30 SEP

KAVIENG 2.5S 150.7E 0016Z 30 SEP

PORT MORESBY 9.3S 146.9E 0039Z 30 SEP

MADANG 5.2S 145.8E 0041Z 30 SEP

MANUS IS. 2.0S 147.5E 0050Z 30 SEP

WEWAK 3.5S 143.6E 0124Z 30 SEP

VANIMO 2.6S 141.3E 0134Z 30 SEP

POHNPEI POHNPEI IS. 7.0N 158.2E 2318Z 29 SEP

WAKE IS. WAKE IS. 19.3N 166.6E 2322Z 29 SEP

PITCAIRN PITCAIRN IS. 25.1S 130.1W 2329Z 29 SEP

MIDWAY IS. MIDWAY IS. 28.2N 177.4W 2349Z 29 SEP

CHUUK CHUUK IS. 7.4N 151.8E 0020Z 30 SEP

AUSTRALIA BRISBANE 27.2S 153.3E 0036Z 30 SEP

SYDNEY 33.9S 151.4E 0038Z 30 SEP

HOBART 43.3S 147.6E 0120Z 30 SEP

CAIRNS 16.7S 145.8E 0123Z 30 SEP

GLADSTONE 23.8S 151.4E 0212Z 30 SEP

MARCUS IS. MARCUS IS. 24.3N 154.0E 0058Z 30 SEP

N. MARIANAS SAIPAN 15.3N 145.8E 0110Z 30 SEP

GUAM GUAM 13.4N 144.7E 0118Z 30 SEP

INDONESIA JAYAPURA 2.4S 140.8E 0138Z 30 SEP

WARSA 0.6S 135.8E 0221Z 30 SEP

ANTARCTICA CAPE ADARE 71.0S 170.0E 0149Z 30 SEP

YAP YAP IS. 9.5N 138.1E 0159Z 30 SEP

BULLETINS WILL BE ISSUED HOURLY OR SOONER IF CONDITIONS WARRANT.

THE TSUNAMI WARNING AND WATCH WILL REMAIN IN EFFECT UNTIL

FURTHER NOTICE.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS

FOR ALASKA...BRITISH COLUMBIA...WASHINGTON...OREGON...CALIFORNIA.

9.4

TSUNAMI BULLETIN NUMBER 004

PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS

ISSUED AT 2136Z 29 SEP 2009

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC

OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...

WASHINGTON...OREGON AND CALIFORNIA.

... TSUNAMI WARNING AND WATCH CANCELLATION ...

THE TSUNAMI WARNING AND/OR WATCH ISSUED BY THE PACIFIC TSUNAMI

WARNING CENTER IS NOW CANCELLED FOR

AMERICAN SAMOA / SAMOA / NIUE / WALLIS-FUTUNA / TOKELAU /

COOK ISLANDS / TONGA / TUVALU / KIRIBATI / KERMADEC IS / FIJI /

HOWLAND-BAKER / JARVIS IS. / NEW ZEALAND / FR. POLYNESIA /

PALMYRA IS. / VANUATU / NAURU / MARSHALL IS. / SOLOMON IS. /

JOHNSTON IS. / NEW CALEDONIA / KOSRAE / PAPUA NEW GUINEA /

HAWAII / POHNPEI / WAKE IS. / PITCAIRN / MIDWAY IS. / CHUUK /

AUSTRALIA / MARCUS IS. / N. MARIANAS / GUAM / INDONESIA /

ANTARCTICA / YAP

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY

NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE

DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND

ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 1748Z 29 SEP 2009

COORDINATES - 15.3 SOUTH 171.0 WEST

DEPTH - 33 KM

LOCATION - SAMOA ISLANDS REGION

MAGNITUDE - 8.3

MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY

GAUGE LOCATION LAT LON TIME AMPL PER

------------------- ----- ------ ----- --------------- -----

PAPEETE TAHITI 17.5S 149.6W 2123Z 0.11M / 0.4FT 10MIN

NUKUALOFA TO 21.1S 175.2W 2007Z 0.14M / 0.5FT 14MIN

PENRHYN CK 9.0S 158.1W 2102Z 0.08M / 0.3FT 04MIN

RAROTONGA CK 21.2S 159.8W 1951Z 0.47M / 1.5FT 08MIN

APIA UPOLU WS 13.8S 171.8W 1832Z 0.70M / 2.3FT 08MIN

PAGO PAGO AS 14.3S 170.7W 1812Z 1.57M / 5.1FT 04MIN

LAT - LATITUDE (N-NORTH, S-SOUTH)

LON - LONGITUDE (E-EAST, W-WEST)

TIME - TIME OF THE MEASUREMENT (Z IS UTC IS GREENWICH TIME)

AMPL - TSUNAMI AMPLITUDE MEASURED RELATIVE TO NORMAL SEA LEVEL.

IT IS ...NOT... CREST-TO-TROUGH WAVE HEIGHT.

VALUES ARE GIVEN IN BOTH METERS(M) AND FEET(FT).

PER - PERIOD OF TIME IN MINUTES(MIN) FROM ONE WAVE TO THE NEXT.

EVALUATION

SEA LEVEL READINGS INDICATE A TSUNAMI WAS GENERATED. IT MAY HAVE

BEEN DESTRUCTIVE ALONG COASTS NEAR THE EARTHQUAKE EPICENTER. FOR

THOSE AREAS - WHEN NO MAJOR WAVES ARE OBSERVED FOR TWO HOURS

AFTER THE ESTIMATED TIME OF ARRIVAL OR DAMAGING WAVES HAVE NOT

PTWC BULLETIN,

Expanding Regional Warning – Cancellation

ISSUED AT 2136Z 29 SEP 2009

ORIGIN TIME - 1748Z 29 SEP 2009

COORDINATES - 15.3 SOUTH 171.0 WEST

DEPTH - 33 KM (fixed)

LOCATION - SAMOA ISLANDS REGION

MAGNITUDE - 8.3

MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY

GAUGE LOCATION LAT LON TIME AMPL PER

------------------- ----- ------ ----- --------------- -----

PAPEETE TAHITI 17.5S 149.6W 2123Z 0.11M / 0.4FT 10MIN

NUKUALOFA TO 21.1S 175.2W 2007Z 0.14M / 0.5FT 14MIN

PENRHYN CK 9.0S 158.1W 2102Z 0.08M / 0.3FT 04MIN

RAROTONGA CK 21.2S 159.8W 1951Z 0.47M / 1.5FT 08MIN

APIA UPOLU WS 13.8S 171.8W 1832Z 0.70M / 2.3FT 08MIN

PAGO PAGO AS 14.3S 170.7W 1812Z 1.57M / 5.1FT 04MIN

LAT - LATITUDE (N-NORTH, S-SOUTH)

LON - LONGITUDE (E-EAST, W-WEST)

TIME - TIME OF THE MEASUREMENT (Z IS UTC IS GREENWICH TIME)

AMPL - TSUNAMI AMPLITUDE MEASURED RELATIVE TO NORMAL SEA LEVEL.

IT IS ...NOT... CREST-TO-TROUGH WAVE HEIGHT.

VALUES ARE GIVEN IN BOTH METERS(M) AND FEET(FT).

PER - PERIOD OF TIME IN MINUTES(MIN) FROM ONE WAVE TO THE NEXT.

European Commission

EUR XXXXX LL – Joint Research Centre – Institute for the Protection and Security of the Citizen

Title: 29 September 2009 Samoa Tsunami

Author(s): A. Annunziato, G. Franchello, E. Ulutas, T. De Groeve

Luxembourg: Office for Official Publications of the European Communities

2009 – 70 pp.

EUR – Scientific and Technical Research series – ISSN 1018-5593

ISBN X-XXXX-XXXX-X

DOI XXXXX

Abstract

On 29 September 2009 at 17:48:11 UTC a large earthquake of magnitude 8 struck offͲshore of the Samoa Islands and

generated a large tsunami that destroyed several villages and caused more than 160 fatalities.

This report first presents the characteristics of the earthquake and discusses the best estimations for the fault

parameters. These are necessary input data for the hydrodynamic tsunami calculations. Then, a comparison between the

nearͲreal time systems and the postͲevent calculations is performed, with an analysis of the observed differences

compared with observed tidal measurements. Coarse, detailed and very detailed calculations are presented in order to

identify areas of maximum damage.

Conclusions are drawn for improvements in the nearͲreal time system