Today We Learn About: 2009 Samoan Earthquake

According to the United States Geological Survey, a massive earthquake struck near the Samoa Islands in the South Pacific on Tuesday, September 29, 2009 at 01:48:10 PM (EDT).1 This earthquake measured at 8.0 on the Richter Scale, and caused massive damage on nearby islands as well as several tsunami that devastated the area. The 2009 Samoa Earthquake occurred where the Pacific Plate subducts underneath the Australia Plate in the Southern Pacific Ocean. There was a tremendous amount of damage on many of the small islands nearby from the earthquake alone. This damage was heightened by the ensuing tsunami that rose from the epicenter of the quake. In response to this earthquake, many countries around the world have sent aid to the region and President Barack Obama has declared the event a major disaster.2

The subduction zone where this quake took place is very active, and has a long history of earthquakes. According to the United States Geological Survey, “The broad-scale tectonics of the Tonga region are 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. At the latitude of the earthquake of September 29, 2009, the Pacific plate moves westward with respect to the interior of the Australia plate at a velocity of about 86 mm/year. The earthquake occurred near the northern end of a 3,000 km long segment of the Pacific/Australia plate boundary that trends north-northeast.; farther north of the earthquake’s source region, the plate boundary trends northwest and then west. The eastern edge of the broad Australia plate may be viewed as a collection of small plates or microplates that move with respect to each other and with respect to the Pacific plate and the Australia plate interior.” This complex region of quakes is fairly desolate, however there are many small islands nearby including French Polynesia, Tonga, Samoa, and American Samoa.

After the earthquake and subsequent aftershocks, the region was hit with a tsunami that caused further devastatation. This tsunami was measured at the following locales and depths (trough to peak); 314 cm at Pago Pago, American Samoa; 140 cm at Apia, Samoa; 47 cm at Rarotonga and 8 cm at Penrhyn, Cook Islands; 41 cm in the Chatham Islands, 37 cm at Raoul, 22 cm at East Cape, 21 cm at North Cape, 21 cm at Tauranga, 16 cm at Napier, 15 cm at Gisborne, 11 cm at Wellington and 3 cm at Waitemata Harbour, New Zealand; 14 cm at Nuku`alofa, Tonga; 11 cm at Papeete, French Polynesia. The island hardest hit by this tsunami was Samoa, where at least 189 people are reported as dead and entire coastal villages have been demolished.3 A tsunami advisory was even issued for California after the quake.4

The devastation of this earthquake caused the United States, New Zealand, and Australian governments to lend aid in the form of paramedics, medicine, doctors, nurses, and other relief supplies. In addition, various aid agencies have taken part in the recovery process including the European Commission through the International Red Cross, Oxfam, The Rotary Club of New Zealand, ANZ Bank of New Zealand, The Federal Emergency Management Agency of The United States, The Church of Jesus Christ of Latter-day Saints, UNICEF, and the Adventist Development and Relief Agency.

This earthquake took a tremendous toll on the infrastructure of the islands involved, and claimed quite a few lives. Unfortunately, this is the price that must be paid for living in such a geologically active part of the world. In the future, perhaps there will be better warnings in place for the tsunami but only time will tell. The more people become educated about the behavior of tsunami, the better, and with time perhaps we will see an improvement in the response of individuals in effected areas.

1Magnitude 8.0 – Samoa Islands Region http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2009mdbi.php#details – Retrieved on November 3rd

2 President Declares Major Disaster For Territory Of American Samoa – http://www.fema.gov/news/newsrelease.fema?id=49596 – Retrieved on November 3rd

4Tsunami Advisory Issued for California After American Samoa Earthquake – http://latimesblogs.latimes.com/lanow/2009/09/tsunami-advisory-for-california-after-american-samoa-earthquake.html

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