amplification of seismic waves: tsunami (seismic sea waves), T&L, Fig waves are: long wave length low amplitude waves are: short wave length high amplitude

Examples of tsunami travel times to Honolulu, T&L, Fig. 11.D

Tsunami (December, 2004) - before

Tsunami (December, 2004) - after

Earthquake Location Magnitude 6.9 SAMOA ISLANDS REGION Thursday, September 28, 2006 at 06:22:09 UTC               

Seismicity in Samoa region Note: Pago Pago is the capitol city of American Samoa Epicenter of earthquake

Tonga - Kermadec trench and island arc The Tonga Trench is located in the Pacific Ocean and is 10,882 meters (35,702 ft) deep at its deepest point. The trench lies at the northern end of the Kermadec-Tonga Subduction Zone, an active subduction zone where the Pacific Plate is being subducted below the Tonga Plate and the Indo-Australian Plate. The Tonga Trench extends north-northeast from the Kermadec Islands north of the North Island of New Zealand. The trench turns west north of the Tonga Plate and becomes a transform fault zone.The convergence is taking place at a rate estimated at approximately 15 cm (6 in) per year (by Lonsdale, 1986); however, recent measurements indicate in places a convergence of 24 cm (10 in) per year across the northern Tonga Trench, which is the fastest plate velocity recorded on the planet (Bevis et al., 1995).

Seismicity Cross Section, Samoa Quake, Sept 29 Epicenter of earthquake

actual tsunami approaches shore in Samoa

Samoa quake 'triggered tsunami‘ Sea level readings following the quake, which had a magnitude of up to 7.0, indicated a tsunami was generated, the Pacific Tsunami Warning Centre said. The quake struck some 300km (185 miles) south-west of Samoa. Waves of 8cm (3.1 inches) high were reported in the American Samoan town of Pago Pago. The Hawaii-based warning centre said the tsunami "may have been destructive along coasts near the earthquake epicentre". Samoa is a small chain of islands that lies half way between New Zealand and Hawaii. Countries around the Indian and Pacific Oceans have been testing systems to warn of approaching tsunamis since the 26 December 2004 earthquake unleashed a tsunami that killed more than 200,000 people. The 9.3 magnitude quake, off the coast of Indonesia, sent waves thousands of kilometres across the Indian Ocean, hitting countries as far apart as the Maldives, Sri Lanka and Somalia. A strong earthquake near the South Pacific nation of Samoa has triggered a small tsunami, a warning centre says.

Flooding after tsunami, Samoa Sept 29, 09