2009 Samoa earthquake
The earthquake in the Samoan islands was a major earthquake on 29 September 2009 at 17:48:10 UTC clock ( Clock 6:48:10 local time). The intensity of the earthquake reached as specified by the United States Geological Survey, a moment magnitude of 8.0 Mw. The hypocenter of the undersea quake was 18 km depth, about 190 kilometers south- southwest of the island of Upolu (Samoa) and about 180 km south-west of the island of Tutuila (American Samoa). The shock triggered a tsunami that caused severe damage in the region of the Samoan islands.
In the southeastern area of the island nation of Samoa some particularly low-lying villages were destroyed. The four tsunami waves that reached the 80 kilometers further east islands of American Samoa were 4-6 meters high and reached about 1.5 miles inland. U.S. President Barack Obama declared the affected, located in American Samoa, Islands a disaster area. Particularly affected were the main island of Tutuila and its capital Pago Pago.
Tsunami
Already at 18:04 clock UTC the Pacific Tsunami Warning Center had issued a tsunami warning for American Samoa, Samoa, Niue, Wallis and Futuna, Tokelau, Cook Islands, Tonga, Tuvalu, Kiribati, Kermadecinseln, Fiji, Howland Island, Baker Island, Jarvis Iceland, New Zealand, French Polynesia and the Palmyra Atoll output. A number of other areas a willingness was proclaimed. For many residents of Samoa and American Samoa came the warning that was forwarded by SMS to late. You barely had time to seek higher ground.
The tsunami reached Pago Pago in American Samoa at 18:25 clock with an amplitude of 1.57 m and Apia in Samoa at 18:29 UTC clock with an amplitude of 0.70 m.
Tectonic overview
The USGS includes the available information, that it is in the earthquake of September 29, is a normal fracture at or near the outer elevation of the subducting Pacific plate.
The large-scale tectonics of the region around Tonga is determined by the relative convergence of the Pacific and Australian plate, the Pacific plate plunges towards the west on the Tonga Trench under the Australian plate. In the vicinity of the earthquake of 29 September 2009, the Pacific plate moves westward with respect to the center of the Australian plate at a speed of about 86 mm per year. The earthquake occurred near the northern end of a 3000 km long section of the border between the two plates, which here runs in a north - northwesterly direction, but then bends to the northwest and finally west. The eastern edge of the Australian plate can thus be considered 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.