A tsunami triggered by an earthquake in the South Pacific slammed into the U.S. territory of American Samoa shortly before 7 a.m. Wednesday, local time, killing nearly three dozen islanders and reportedly demolishing the headquarters and visitor center of the National Park of American Samoa.
Cellphone messages relayed to officials in the National Park Service's Pacific West regional office in California said a series of five waves battered the park's two-story building, which stands about 50 feet from the harbor waters in the capital of Pago Pago on the island of Tutuila.
"Our park superintendent (Mike Reynolds) was in the building when the first wave hit. That was early in the morning. He and this other staffer, (Ranger) Sarah Bone, ran out of the building and up hill, and made a call to our Honolulu office," Holly Bundock, assistant regional director for communications in the Park Service's Pacific West office, said Tuesday afternoon. “The last report was five waves and one as high as 30 feet.”
The Associated Press reported that at least 34 islanders were killed by the waves. Ms. Bundock said there weren't any reports of injuries or deaths among the park's staff, which she said counts 13-15 full-time employees and 30-50 volunteers.
"Every report we get, more and more employees are showing up, which is a great relief to us," she said. "It was so early in the morning people hadn’t actually arrived for work yet. Now we’re kind of focused on assisting the Coast Guard and any kind of emergency service operation.”
The U.S. Geological Survey measured the earthquake at a magnitude of 8.0 and said its epicenter was centered 11.2 miles below the ocean about 125 miles south of Apia on the independent state of Samoa.
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.
On the basis of currently available location and fault mechanism information, we infer that the September 29 earthquake occurred as a normal fault rupture on or near the outer rise of the subducting Pacific plate.
The broad-scale Australia/Pacific plate boundary is one of the most active earthquake regions in the world. Earthquakes occur on the thrust-fault boundary between the Australia and Pacific plates, within the Pacific plate on both sides of the trench, and within and on the boundaries of the small plates that compose the eastern edge of the overall Australia plate.