Earthquake in the Samoan Islands in 2009

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The hypocenter of the earthquake was south-southwest of Apia
NOAA simulation of the tsunami spread of September 29, 2009
Workers remove damage from the tsunami in Samoa

The earthquake in the Samoan Islands was a major earthquake on September 29, 2009 at 17:48:10 UTC (6:48:10 local time). According to the United States Geological Survey, the intensity of the earthquake reached a moment magnitude of 8.0 M w . The hypocenter of the submarine quake was at a depth of 18 km, around 190 kilometers south-southwest of the island of Upolu (Samoa) and around 180 km southwest of the island of Tutuila (American Samoa). The tremor triggered a tsunami that caused severe damage in the Samoan region .

In the southeastern region of the island state of Samoa , some particularly low-lying villages were destroyed. The four tsunami waves, which also reached the islands of American Samoa around 80 kilometers to the east , were between 4 and 6 meters high and reached about 1.5 kilometers inland. US President Barack Obama declared the affected islands in American Samoa a disaster area. The main island of Tutuila and its capital Pago Pago were particularly hard hit .

Tsunami

At 18:04 UTC the Pacific Tsunami Warning Center had already issued a tsunami warning for American Samoa, Samoa, Niue , Wallis and Futuna , Tokelau , the Cook Islands , Tonga , Tuvalu , Kiribati , Kermadec Islands , Fiji , Howland Island , Baker Island , Jarvis Island , New Zealand , French Polynesia and the Palmyra Atoll . Readiness has been declared for a number of other areas. For many Samoan and American Samoan residents, the SMS-relayed warning came too late. They hardly had time to go to higher areas.

The tsunami reached Pago Pago in American Samoa at 6:25 pm with an amplitude of 1.57 m and Apia in Samoa at 18:29 UTC with an amplitude of 0.70 m.

Amplitude of the tsunami
place Coordinates Time (UTC) amplitude
Apia, Samoa 13.8 ° S; 171.8 ° W 18:29 0.70 m
Pago Pago, American Samoa 14.3 ° S; 170.7 ° W 18:25 1.57 m
Rarotonga , Cook Islands 21.2 ° S; 159.8 ° E 19:50 0.54 m
Port Vila , Vanuatu 17.8 ° S; 168.3 ° E 22:39 0.18 m
Nawiliwili ( Kauai ), Hawaii 22.0 ° N; 159.4 ° W 00:15 0.20 m
Honolulu ( Oahu ), Hawaii 21.3 ° N; 157.9 ° W 00:31 0.16 m
Kahului ( Maui ), Hawaii 20.9 ° N; 156.5 ° W 01:13 0.36 m
Easter Island , Chile 27.1 ° S; 109.3 ° W 03:42 0.25 m
Shemya , Alaska 52.7 ° N; 174.1 ° E 04:56 0.10 m
Arena Cove , California 38.9 ° N; 123.7 ° W 04:59 0.33 m
Port Orford , Oregon 42.7 ° N; 124.5 ° W 05:09 0.17 m
Monterey Harbor , California 36.6 ° N; 121.9 ° W 05:25 0.15 m
Charleston , Oregon 43.3 ° N; 124.3 ° W 05:28 0.13 m
San Francisco , California 37.8 ° N; 122.5 ° W 05:29 0.08 m
Port San Luis, California 35.2 ° N; 120.8 ° W 05:31 0.30 m
South Beach , Oregon 44.6 ° N; 124.0 ° W 05:45 0.09 m
Crescent City , California 41.7 ° N; 124.2W 06:13 0.21 m
Source: West Coast and Alaska Tsunami Warning Center

Tectonic overview

Based on the information available, the USGS concludes that the September 29 earthquake was a normal fracture at or near the outer ridge of the descending Pacific plate.

The large-scale tectonics of the region around Tonga is determined by the relative convergence of the Pacific and Australian plates , with the Pacific plate dipping to the west at the Tonga Trench below the Australian plate. Near the September 29, 2009 earthquake, the Pacific Plate is moving westward relative to the center of the Australian Plate at a rate of about 86 mm annually. The earthquake occurred near the northern end of a 3000 km long section of the boundary between the two plates, which here runs in a north-northwest direction, but then bends to the northwest and finally to the west. The eastern edge of the Australian plate can thus be viewed as a collection of small plates or microplates that move relative to each other and also with respect to the Pacific plate and the center of the Australian plate. The plate boundary between Australia and the Pacific is one of the most active earthquake regions in the world.

Damage

The Guardian reported 189 earthquake and tsunami fatalities, including 31 in American Samoa, 149 in Samoa and 9 in Tonga.

Individual evidence

  1. ↑ Magnitude 8.0 - SAMOA ISLANDS REGION ( English ) United States Geological Survey. September 29, 2009. Retrieved October 1, 2009.
  2. ^ FEMA: President Declares Major Disaster For Territory Of American Samoa. Date: September 29, 2009, English ( Memento of October 8, 2009 in the Internet Archive )
  3. ↑ Quake in Samoa and Sumatra: Dead and Devastation
  4. ↑ TSUNAMI BULLETIN NUMBER 001 ( English , TXT) Pacific Tsunami Warning Center. September 29, 2009. Archived from the original on October 2, 2009. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 2, 2009. @1@ 2Template: Webachiv / IABot / www.prh.noaa.gov
  5. ↑ Tsunami Advisory # 7 issued 09/29/2009 at 9:28 PM PDT ( English , TXT) West Coast and Alaska Tsunami Warning Center. September 29, 2009. Archived from the original on October 3, 2009. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 2, 2009. @1@ 2Template: Webachiv / IABot / wcatwc.arh.noaa.gov
  6. ↑ Tsunami Advisory Cancellation # 9 issued 09/30/2009 at 1:28 AM PDT ( English , TXT) West Coast and Alaska Tsunami Warning Center. September 29, 2009. Archived from the original on October 3, 2009. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 2, 2009. @1@ 2Template: Webachiv / IABot / wcatwc.arh.noaa.gov
  7. ↑ Magnitude 8.0 - SAMOA ISLANDS REGION - Earthquake summary ( English ) United States Geological Survey. Retrieved October 1, 2009.
  8. ↑ Surfer survived Samoa tsunami by riding out the waves. In: The Guardian . October 2, 2009, accessed August 21, 2015 .

Web links

 Wikinews: Severe earthquake in Samoa leads to tsunami  - news
Commons : Earthquake in the Samoan Islands 2009  - Collection of pictures, videos and audio files

Coordinates: 15 ° 31 ′  S , 172 ° 2 ′  W