29 September 2009, Mw 8.0, Samoa Islands

2009-09-30T17:57:27+00:00

The 29 September 2009 M7.9 earthquake generated a tsunami that caused deaths and casualties in Samoa, American Samoa, and Tonga, and damage in Wallis and Futuna. Strong shaking was felt for a period of at least 60 s with some eyewitnesses reporting more than two minutes. The tsunami arrived 10-20 min after earthquake shaking stopped in Samoa, American Samoa, and Tonga, and caused deaths in Samoa (149), Am Samoa (34), and Tonga (9). Maximum run-up’s of 16-17+ m were measured in all three countries. Extensive coastal damage to structures and marine / coral reef, and lagoon ecosystems occurred. The international alert system (PTWC) provided its first messages (preliminary earthquake observatory message) 11 minutes after the earthquake and an official warning 16 min after the earthquake. In order to improve on the timeliness of alerting, improvements in seismic networks are required, and these have been progressing actively for the Southwest Pacific since 2007.

However, through numerous Pacific Tsunami Warning and Mitigation System (PTWS) working groups over the last decade and other workshops and trainings by ITIC and PTWS countries, it is well-known that for local tsunamis, education, awareness, preparedness before the event and heeding of natural warnings when it does occur are the most important activities for saving lives. In other words, no one should be wait for an official alert to evacuate. Rather, if they are living near the coast and a strong earthquake occurs and/or unusual/abnormal sea level activities are seen or load roars are heard, everyone should go to higher ground and inland immediately!

This was clearly demonstrated in American Samoa and Samoa, where both countries had actively engaged in pre-event awareness and education. For last decade, this has been carried out continuously in American Samoa and September 2009 was American Samoa Disaster Preparedness month. Additionally, the Pacific Wave 2006 and 2008 helped to prepare countries, their agencies, and their peoples for the next tsunami.

Factors which helped to reduce vulnerability for this event were the time of day (many were already awake, but not on the road and the work day had not started), generally limited earthquake damage which reduced injuries and damage to transportation infrastructure, relative closeness and availability of high ground, pre-event plans (such as school evacuation plans in American Samoa) and school and community drills (National Drill in 2007 and 2008 in Samoa). The 2004 Indian Ocean tsunami, and more recently, the 19 March earthquake off Tonga, also served as reminders of what tsunamis can do, and how warning and response agencies need to coordinate and respond.

Today, the countries are working on recovery issues, and improving their early warning and alert systems, especially in hardening the communications infrastructures critical for providing information on warning and evacuation. Both traditional methods of alerting (bells), and modern media (sirens, mobile phone alerting, radio/TV broadcast), are being strengthened. In addition, at the community and village levels, education and preparedness continues such as the development and/or clarification of evacuation maps and routes to safe areas. As the countries build back, they are doing so in ways which acknowledge and recognize that traditional building practices (open fales) survived well.

1) Alert Information	International PTWC Official Messages - (DOC 99.5 KB) US NOAA Pacific Tsunami Warning Center WC/ATWC Official Messages - (DOC 123 KB) US NOAA West Coast & Alaska Tsunami Warning Center ITIC Timeline - (DOC 105 KB) UNESCO/IOC - NOAA International Tsunami Information Center
2) Sea Level	Sea Level Observations - (DOC 27.0 KB) US NOAA Pacific Tsunami Warning Center Sea Level Observations - (DOC 24.0 KB) National Institute of Water & Atmospheric Research Sea Level Observations - (DOC 30.5 KB) US NOAA Pacific Tsunami Warning Center Dart Observations - (DOC 24.0 KB) US NOAA Pacific Tsunami Warning Center Sea Level Records SW Pacific summary, as of 2239Z, 29 Sept - (DOC 311 KB) UNESCO/IOC - NOAA ITIC SW Pacific, as of 0000Z, 30 Sept - (DOC 909 KB) Apia, Pago Pago (PAGO, PAGX), Papeete, Penryn, Rarotonga (RARO, RARB), Tonga, Upolu, Kiribati (XMAS) UNESCO/IOC - NOAA ITIC Around Hawaii, as of 0138X, 30 Sept - (DOC 558 KB) Nawiliwili, Honolulu, Kahalui, Hilo, Kawaihae, Kaumalapau, Moku, Johnston Island UNESCO/IOC - NOAA ITIC Coastal Sea Level Data and Graphs - (Website) US NOAA West Coast & Alaska Tsunami Warning Center Pacific basin, WC/ATWC - (ZIP 5.36 MB) 69 sea level stations Russia - (JPG 115 KB) Severo-Kurilsk Tide Gauge Sakhlin Tsunami Warning Center, Russia Russia - (JPG 66.0 KB) Malokurilsk Station Institute of Marine Geology and Geophysics New Zealand - (PDF 539 KB) NIWA, Rob Bell
3) Seismic	U.S. Geological Survey PTWC Historical Earthquake Plot - (JPG 175 KB) US NOAA Pacific Tsunami Warning Center Historical Seismicity - (JPG 175 KB) Earthquake Plot - (JPG 57.2 KB) Seismicity Cross Section - (JPG 137 KB) Global CMT Project Moment Tensor Solution - (PDF 8.27 KB) Earthquake Summary Poster - (PDF 5.01 MB)
4) Model Simulations	NOAA PMEL Center for Tsunami Research - (Website) Tsunami Propagation Animation - (MOV 31 MB) Maximum Wave Amplitude Distribution - (PNG 1.04 MB) Disaster Control Research Center, Tohoku University (Website) European Commision Joint Research Center Global Disaster Alert and Coordination System SWAN-JRC Tsunami Model Tsunami Wave Model Heights - Tutuila, Upolu, Savai'i - (PDF 3.52 MB) URS Corporation, Oct 7, 2009
5) Media	Quake Near Samoa Sets Off Tsunami The New York Times Major earthquake hits Samoa, tsunami warning enforced Samoalivenewsline Deadly tsunami strikes in Pacific BBC At least seven dead after quake, tsunami hit Samoa The New Zealand Herald Homes reported swept away in Samoa Honolulu Star-Bulletin Tsunami watch canceled but officials say stay out of the water today Honolulu Star-Bulletin Tsunami death toll climbs to 119 Honolulu Star-Bulletin Destruction and death left in wake Honolulu Star-Bulletin Pacific tsunami: Aid efforts begin in Samoa The Christian Science Monitor Updates on the Tsunami in Samoa The New York Times Aid Flows to Tsunami-Hit Samoas; Death Toll at 119 The New York Times The Day of the Tsunami The New York Times NZ aid arrives in Samoa The New Zealand Herald They have just minutes to issue tsunami warning CNN How Prepared Are Countries for a Tsunami? Time
6) Photos	Tsunami warning system passes its first test Bureau of Meteorology (BOM), Australia In pictures: Pacific tsunami BBC Strong quake triggers tsunami in Samoa Yahoo News Samoa Tsunami Gordon Y. (NOAA) Tsunami brings terror to Samoa, Tonga The New Zealand Herald Tsunami Wipes Out Villages in South Pacific The Wall Street Journal
7) Post-Tsunami Surveys	American Samoa Inspection of the tsunami impacted area in American Samoa by the Integration of Tsunami Model and High-resolution satellite images Disaster Control Research Center, Tohoku University Digital Globe Quickbird images 4 hrs after earthquake - (PDF 1.38 MB) The Limit of Inundation of the September 29, 2009, Tsunami on Tutuila, American Samoa USGS Report - PDF (13.2 MB) Inundation Line Data - ZIP (1.6 MB) Metadata - ZIP (13.3 KB) 29 September 2009 Tsunami and Earthquake (2009 Fall AGU Meeting) Titles and Abstracts Samoa Inspection of the tsunami impacted area in American Samoa by the Integration of Tsunami Model and High-resolution satellite images - (Website) Disaster Control Research Center, Tohoku University Tonga 29 September 2009, Mw 8.0, Samoa Islands - Post-tsunami survey of Niuatoputapu Island, Tonga, following the 30th September 2009 South Pacific tsunami GNS Science Report 2009/71 Inspection of the tsunami impacted area in American Samoa by the Integration of Tsunami Model and High-resolution satellite images - (Website) Disaster Control Research Center, Tohoku University

2009 Tsunamis - International Tsunami Information Center

29 September 2009, Mw 8.0, Samoa Islands