Samoa Samoa 2009 (CAR)

back to event list
Event ID
200909291748
Event name
Samoa
Country
Samoa
World region
Oceania
Epicentral coordinates (long/lat)
POINT(-172.03 -15.51)
WKT GIS format
GEMECD contributing partner
CAR
Event narrative

On Tuesday September 29, 2009 at 6:48 am local time an unprecedented earthquake doublet[1] occurred in the South Pacific triggering a large tsunami that affected the islands of Samoa (180000 inhabitants), American Samoa (65000 inhabitants) and Tonga’s Niua group (~1000 inhabitants).

The first earthquake of the doublet with moment magnitude (Mw) 8.0 and depth of 18 km occurred 190 km south of Apia, Samoa and 75 km east of Tonga’s Niua Group (15.51 S,172.03 W); it was generated by an intraplate normal fault rupture in the outer rise of the subducting Pacific plate.

The second earthquake, occurred within two minutes and was composed by two major interplate underthrusting subevents (each of which of Mw 7.8) with a combined Mw 8.0[1].

The broad-scale tectonic setting of the region is dominated by the relative convergence of the Pacific and Australia plates, with the Pacific plate subducting westward beneath the Australia plate at the Tonga trench (USGS, 2009).

The earthquake induced ground motion was consciously felt (MM V-VI[2]) from the people in the affected areas so that educated people immediately appreciated the possible threat of a subsequent tsunami and moved to higher ground. According to EERI evacuation exercises had been conducted in Samoa in the preceding year, and many schools in American Samoa practiced monthly evacuation drills[3]. The awareness of tsunami hazard among the population saved many lives.

In fact, the ensuing tsunami, due the proximity of the earthquake to the coast, reached some of the hardest hit villages before that the Pacifc Tsunami Warning Center issued the tsunami warning (16 minutes after the earthquake[3]).

1 Goff, J., Dominey-Howes, D., 2011. The 2009 South Pacific Tsunami, Earth-Science Reviews, Volume 107, Issues 1–2, July 2011, Pages 5-7, ISSN 0012-8252, http://dx.doi.org/10.1016/j.earscirev.2011.03.006.
2 http://earthquake.usgs.gov/earthquakes/pager/events/us/2009mdbi/
3 EERI, 2010. Samoa Earthquake and Tsunami of September 29, 2009. Special Earthquake Report — January 2010.

Date of occurrence (UTC)
2009-09-29
date
Time of occurrence (UTC)
17:48:10
time
Date of occurrence (local)
2009-09-29
date
Time of occurrence (local)
06:48:10
time
Day of the week (local)
Tuesday
Magnitude
8
Magnitude units
Moment (Mw)
Focal depth
18
km
Seismological data: source
USGS
Seismological data: comment

ShakeMap Atlas

Overall impact

The tsunami seriously impacted the islands of Upolu (maximum runup reached 14m[4]), and Savai'i (maximum runup exceeded 8m[4]) in Samoa; Tutuila (maximum runup reached 14m[4]), the main island of American Samoa, and Niuatoputapu Island in Tonga (flow depth of 15 m[4]). Inundation distance in the villages were typically 100-500 m from the coast with a maximum of 1 km observed in Niuatoputapu.

Widespread damage was seen throughout Samoa and American Samoa. While most of the reinforced concrete buildings withstood the tsunami (suffering mainly non-structural damage), timber structures were in many cases torn off from their foundations. According to the housing program final assessment, 502 housing units were destroyed and another 360 were damaged but repairable in Samoa [5] (566 housing units damaged or destroyed according to the Disaster Management Office[6]) leaving around 3200 people homeless; in Niuatoputapu 89 houses were destroyed and 56 partially damaged out of the 225 houses on the island with around 300 people made homeless[7]; in American Samoa 241 homes and one school were destroyed, 308 homes and four schools had major damage and another 2,750 dwellings reported some damage[8] causing around 3000 displaced people.

Infrastructures (road and bridges) and lifeline systems (water and power systems) were seriously affected across large areas.

The human toll counted 143 deaths, 5 missing and 310 treated patients in Samoa, 32 deaths and at least 50 injuries in American Samoa and 9 deaths and 7 serious injuries in Niuatoputapu (mostly children, women and elderly).

The overall economic loss for Samoa was estimated at 124 million USD (24.7% of Samoa’s GDP) out of which 84.8 million USD direct loss and 39.2 million USD indirect loss[6]. The overall economic loss in Niuatoputapu were stated by OCHA at 9.5 million USD (about 3% of Tonga’s GDP). According to U.S. Department of Homeland Security federal assistance to American Samoa, including FEMA’s operational expenses exceeded 125.5 million USD, and an additional 4.3 million USD were planned for future distribution[8].

4 Fritz, H. M., Borrero, J. C., Synolakis, C. E., Okal, E. A., Weiss, R., Titov, V. V., Jaffe, B. E., Foteinis, S., Lynett, P. J., Chan, I.C., Liu, P. L. F., 2011. Insights on the 2009 South Pacific tsunami in Samoa and Tonga from field surveys and numerical simulations, Earth-Science Reviews, 107, Issues 1–2, pp. 66-75, ISSN 0012-8252. http://dx.doi.org/10.1016/j.earscirev.2011.03.004.
5 New Zealand Aid Programme
http://www.aid.govt.nz/media-and-publications/stories-and-features/octob...
6 SAMOA. Post-Disaster Needs Assessment. Following the Earthquake and Tsunami of 29th September 2009. Government of Samoa. December 2009.
http://www.gfdrr.org/sites/gfdrr.org/files/documents/PDNA_Samoa_2009.pdf
7 OCHA, 2009. Samoa/Tonga - Tsunami Situation Report #6 Date: 6 October 2009
8 U.S. Department of Homeland Security (2010), American Samoa 2009 Earthquake and Tsunami: After-Action Report. Available at URL: http://www.oig.dhs.gov/assets/Mgmt/OIG_11-03_Oct10.pdf

Overview data
Loss: Human Casualty
show
hide
People injured
700
number
People injured: source
CAR estimate based on: OCHA Samoa/Tonga: Tsunami Situation Report No. 11 (Oct 22, 2009); FEMA: American Samoa Tsunami recovery (Oct 15, 2009) from: http://reliefweb.int Samoa Medical Journal, Vol. 2, Issue 1, 2010 from http://www.oceaniamed.org
People injured: comment

310 treated in Samoa (data available only from Oct 5-16) incl. people with chronic treatments that had lost their medicine supplies in the tsunami. Many injured did not visit hospitals for treatment. 7 seriously injured in Tonga (many more with minor injuries) . Initially 50 injuries in American Samoa (http://pacificeye.wordpress.com/2009/10/28/update-on-niuatoputapu-tonga-...) but hundreds in total.

People injured: status
Greater than

People seriously injured
100
number
People seriously injured: source
CAR estimate based on: Samoa Medical Journal, Vol. 2, Issue 1, 2010 & OCHA Situation Report No. 11.
People seriously injured: comment

64 treated for wounds and (or) infections after Oct 5 in Samoa. 7 seriously injured in Tonga (OCHA).

People seriously injured: status
Greater than

People missing
5
number
People missing: source
OCHA: Samoa/Tonga: Tsunami Situation Report No. 11 (Oct 22, 2009); FEMA: American Samoa Tsunami recovery (Oct 15, 2009) from: http://reliefweb.int/disaster/ts-2009-000209-asm?search=&page=8
People missing: comment

5 people missing in Samoa, no missing in American Samoa and Tonga.


People killed
184
number
People killed: source
OCHA: Samoa/Tonga: Tsunami Situation Report No. 11 (Oct 22, 2009); FEMA: American Samoa Tsunami recovery (Oct 15, 2009) from: http://reliefweb.int/disaster/ts-2009-000209-asm?search=&page=8
People killed: comment

143 died in Samoa, 32 in American Samoa and 9 on Niuatoputapu Island, Tonga.


People killed due to ground shaking
0
number

People dying post catastrophe due to shaking
1
number
People dying post catastrophe due to shaking: source
Samoa Medical Journal, Vol. 2, Issue 1, 2010.
People dying post catastrophe due to shaking: comment

1 old lady that died in Samoa hospital after her rescue


People missing due to tsunami
5
number
People missing due to tsunami: source
OCHA: Samoa/Tonga: Tsunami Situation Report No. 11 (Oct 22, 2009); FEMA: American Samoa Tsunami recovery (Oct 15, 2009) from: http://reliefweb.int/disaster/ts-2009-000209-asm?search=&page=8
People killed due to tsunami
184
number
People killed due to tsunami: source
OCHA: Samoa/Tonga: Tsunami Situation Report No. 11 (Oct 22, 2009); FEMA: American Samoa Tsunami recovery (Oct 15, 2009) from: http://reliefweb.int/disaster/ts-2009-000209-asm?search=&page=8
People missing due to fire following
0
number
People killed due to fire following
0
number
People missing due to slope failures
0
number
People killed due to slope failures
0
number
Loss: Building damage
show
hide
Total number of buildings destroyed
833
number
Total number of buildings destroyed: source
http://www.aid.govt.nz/media-and-publications/stories-and-features/october-december-2010/new-zealands-role-pacific-tsunami-; OCHA, Report #6 6/10/2009; U.S. DHS (2010) American Samoa 2009 Earthquake and Tsunami: After-Action Report; PDNA, 2009.
Total number of buildings destroyed: comment

502 in Samoa (it refers to 502 houses replaced in Samoa as reported by the New Zealand Aid Programme, there were also non-residential buildings destroyed in Samoa but their number has not been reported); 242 in American Samoa (it refers to 241 houses and 1 school as reported by the U.S. department of homeland security, no information about non-residential buildings); and 89 in Niuatoputapu, Tonga (it refers to 89 destroyed houses as reported by OCHA 6/10/2009, no information about non-residential buildings).

Total number of buildings destroyed: status
Approximate

Number of buildings damaged
3642
number
Number of buildings damaged: source
http://www.aid.govt.nz/media-and-publications/stories-and-features/october-december-2010/new-zealands-role-pacific-tsunami-; OCHA, Report #6 6/10/2009; U.S. DHS (2010) American Samoa 2009 Earthquake and Tsunami: After-Action Report; PDNA, 2009.
Number of buildings damaged: comment

524 in Samoa (incl. 360 repaired houses as reported by New Zealand Aid Programme and 164 non-residential buildings damaged or destroyed as reported by PDNA, 2009); 3062 in America Samoa (it refers to 308 houses and 4 schools with major damage and 2750 houses with minor damage as reported by the U.S. department of homeland security, no information on non-residential buildings); and 56 in Tonga (it refers to 56 damaged houses as reported by OCHA 6/10/2009, no information on non-residential buildings).

Number of buildings damaged: status
Approximate

Number of dwellings destroyed
832
number
Number of dwellings destroyed: source
http://www.aid.govt.nz/media-and-publications/stories-and-features/october-december-2010/new-zealands-role-pacific-tsunami-; OCHA, Report #6 6/10/2009; U.S. DHS (2010) American Samoa 2009 Earthquake and Tsunami: After-Action Report.
Number of dwellings destroyed: comment

502 in Samoa (this number is based on the final assessment of the housing program “tsunami shelter recovery poject” which provided funds to 502 families to rebuilt their homes as reported by New Zealand Aid Programme); 241 in American Samoa (it refers to 241 houses destroyed as reported by U.S. Department of Homeland security); and 89 in Niuatoputapu, Tonga (it refers to 89 destroyed houses as reported by OCHA 6/10/2009).

Number of dwellings destroyed: status
Approximate

Number of dwellings damaged
3474
number
Number of dwellings damaged: source
http://www.aid.govt.nz/media-and-publications/stories-and-features/october-december-2010/new-zealands-role-pacific-tsunami-; OCHA, Report #6 6/10/2009; U.S. DHS (2010) American Samoa 2009 Earthquake and Tsunami: After-Action Report.
Number of dwellings damaged: comment

360 in Samoa (it is based on the final assessment of the housing program “tsunami shelter recovery poject” which provided funds to 360 families to repair their homes as reported by New Zealand Aid Programme); 3058 in American Samoa (it refers to 308 houses with major damage and 2750 dwellings with minor damage as reported by U.S. Department of Homeland Security); 56 in Niuatoputapu, Tonga (it refers to 56 damaged houses as reported by OCHA 6/10/2009).

Number of dwellings damaged: status
Approximate

Total number of buildings destroyed by shaking
0
number
Total number of buildings destroyed by shaking: source
EERI, 2010. Samoa Earthquake and Tsunami of September 29, 2009. Special Earthquake Report — January 2010
Total number of buildings destroyed by shaking: comment

Little earthquake damage: Shaking damage was minimal and did not disrupt roads or structures (EERI, 2010)


Number of buildings damaged by shaking: status
N/A

Number of dwellings destroyed by shaking
0
number
Number of dwellings destroyed by shaking: source
EERI, 2010. Samoa Earthquake and Tsunami of September 29, 2009. Special Earthquake Report - January 2010
Number of dwellings destroyed by shaking: comment

Little earthquake damage: Shaking damage was minimal and did not disrupt roads or structures (EERI, 2010)


Number of dwellings damaged by shaking: status
N/A

Loss: Socioeconomic
show
hide
People homeless
8600
number
People homeless: source
CAR estimate from miscellaneous sources
People homeless: comment

4500 people directly affected by the tsunami in Samoa, 300 in Tonga, 3000 in American Samoa. Swiss Re reports 15000 homeless. Samoa PDNA report says: 5274 people affected.

People homeless: status
Approximate

Direct economic loss
244
million US$
Direct economic loss: source
GFDRR Samoa PDNA report; OCHA Samoa/Tonga: Tsunami Situation Report No. 11 (Oct 22, 2009); US Departm. of Homeland Security After-Action Report.
Direct economic loss: comment

The direct economic loss in Samoa was estimated by GFDRR at 84.8 million USD (16.9% of Samoa’s GDP). OCHA reports 9.5 million USD loss in Tonga (3% of GDP). In American Samoa, 149.9 million USD was spent for debris removal, protective measures, reconstruction/repair of public buildings & infrastructure, assistance grants to 321 affected heads of family and the cost for recovery in the housing sector and other disaster needs. More funds (unspecified) were used to reconstruct 45 homes and to provide temporary housing and sheltering to the homeless.

Direct economic loss: status
Greater than

Indirect economic loss
100
million US$
Indirect economic loss: source
GFDRR Samoa PDNA report; U.S. Department of Homeland Security After-Action Report.
Indirect economic loss: comment

The indirect losses in Samoa were estimated at 39.2 million USD (GFDRR). In American Samoa, the costs for FEMA’s operational expenses were around 56.5 million USD (45% of the Federal assistance of 125.5 million USD provided).

Indirect economic loss: status
Approximate

Demographics
show
hide
Total number of buildings: status
N/A