The information presented here is focused on geologic aspects of the disaster. Starting in 2007, Samoa ran National Tsunami Drills in Apia to prepare for tsunamis, raising public awareness that during a worst-case scenario, villages would have only 15 minutes before the tsunami arrived. Widespread damage was reported to the infrastructure at Pago Pago, American Samoa, in many parts of Samoa and on Niuatoputapu, Tonga.
Image caption The 2009 tsunami devastated the South Pacific islands of Tonga and Samoa . These are external links and will open in a new window
The small South Pacific island of Niuatoputapu and its nearby volcanic cone Tafahi, along with a distant neighbor Niuafo‘ou, form a remote region known as the “Niuas,” located in the far north of the Tonga islands.
Prior to the tsunami in 2009, Samoa also hosted two international meetings that brought attention to the local hazardous conditions that is common to many Southwest Pacific island nations.
According to the June 18 U.S. Drought Monitor, moderate to extreme drought covers 4.0% of the United States. Samoa was hit by a tsunami and earthquake on 29 September 2009.
Scientists say the tsunami that devastated the islands of Samoa, American Samoa and Tonga was the result of a shallow rupture in the earth's crust. Samoa is very low lying with its highest point being 2000m above sea level and it’s average height at 2.3 meters above sea level. In this region, the Pacific plate subducts westward beneath the Australia plate at the Tonga Trench. "Gibson says residents of the nearby islands would have felt the earthquake last for at least a minute, which is a sure sign of an impending tsunami.
Preliminary field survey data of American Samoa indicates that the tsunami runups (height above ambient sea level) reached as much as 12 m, which is larger than most tsunamis generated by magnitude 8.0 earthquakes on the inter-plate thrust. September 29, 2009 Samoa Tsunami, Southwest Pacific OceanThe tsunami that was triggered by a magnitude 8.1 earthquake on September 29, 2009, caused significant damage and loss of life on Samoa, American Samoa, and Tonga.
The 1933 Sanriku tsunami generated from a Outer-rise earthquakes are caused by stresses in the subducting, oceanic plate induced by bending as the plate enters the trench.Flexure of the plate elevates the sea floor, creating an oceanic feature known as an "outer rise" that parallels the oceanic trench. Widespread damage was reported to the infrastructure at Pago Pago, American Samoa, in many parts of Samoa and on Niuatoputapu, Tonga. Crustal stresses caused by earthquakes on the inter-plate thrust fault in subduction zones can also be transferred to the outer rise, triggering earthquakes on At the Tonga trench, the Pacific plate entering the subduction zone is particularly old and dense, resulting in a steep angle of descent and many normal faults near the trench. Click on a pin on the map to see more information.
However, the events of September 29 involved a magnitude 8.1 earthquake on a normal fault within the outer rise; and the other magnitude 8.0 earthquake occurred on the subduction zone as a thrust event.The earthquake was felt in American Samoa for up to 3 minutes, giving emergency responders, local government officials, and the public time to respond to natural warning signs because they understood the threat.Thanks to education and outreach efforts held over the summer and fall of 2009, many organizations and individuals knew the signs of an impending tsunami and had developed tsunami evacuation plans.Similar to American Samoa, knowledge of the threat and recognition of a tsunami’s natural warning signs saved many lives in Samoa.
This process is sometimes referred to as “shoaling amplification”. In the hopes that disasters such as this can be minimized in the future, we attempt to understand the mechanism and impact of this tsunami. The deadly 2009 tsunami was triggered by at least two separate earthquakes occurring within 2–3 minutes of each other near the Tonga Trench The tsunami waves measuring 4.5m at peak first arrived at Pago Pago, American Samoa approximately 250 km from earthquake epicenter.