Acehtsunami

Aid from New Zealand to Pacific tsunami victims was delayed for more than a week by a tender process, leaving Foreign Affairs Minister Murray McCully “stunned” and “disappointed”.
As a result, the Government is setting up two new multimillion-dollar funds to speed up disaster assistance.

Mr McCully told the foreign affairs and trade select committee this week that he was disappointed a time-consuming tender process was needed before money could be allocated to aid agencies after the Pacific earthquake and tsunami last September.

“I was stunned after the Pacific tsunami that we had to go through a short-form tender process to issue funds that needed to be allocated within hours,” Mr McCully conveyed.

Newly discovered tsunami deposits imply that the Japanese coastline was hammered by a series of massive waves thousands of years ago. The finding adds to growing proof that the region is regularly pounded by killer waves, and could help in planning for future inundations. The northern Japanese island of Hokkaido is huddled up against the Kuril-Kamchatka trench, a place where the Pacific tectonic plate dives beneath the Eurasian plate and home to terrible earthquakes in excess of magnitude 8.0.
Now Wesley Nutter and a team of researchers say nine waves, each at least 33 feet high, thrashed the coastline before the dawn of civilization on the island. “In recorded history, tsunamis have hit the Hokkaido coast over and over again,” Wesley Nutter of Earlham College in Indiana said. “But something of that size has never been recorded here.”
Nutter and a team of researchers dug down into the sediments of a saltwater marsh on the island looking for signs of past tsunamis. Team member Kazuomi Hirakawa of Hokkaido University had first detected a series of sand deposits several years ago there that had no business in a marsh mostly made of peat. Tracing the sand deposits away from the coast, the team found they extend up to more than a mile inland and get thinner further from the sea.

A NASA-led research team has successfully displayed for the first time elements of a prototype tsunami prediction system that quickly and accurately assesses large earthquakes and estimates the size of resulting tsunamis. After the magnitude 8.8 Chilean earthquake on Feb. 27, a team led by Y. Tony Song of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., used real-time data from the agency’s Global Differential GPS (GDGPS) network to successfully foresee the size of the resulting tsunami. The network, managed by JPL, unites global and regional real-time data from hundreds of GPS sites and estimates their positions every second. It can detect ground motions as small as a few centimeters.

When the Feb. 27, 2010, earthquake struck, its ground movement was captured by the NASA GDGPS network’s station in Santiago, Chile, about 235 kilometers (146 miles) from the earthquake’s epicenter. These data were made accessible to Song within minutes of the earthquake, enabling him to derive the seafloor motions. Based on these GPS data, Song determined the tsunami’s source energy, ranking it as moderate: a 4.8 on the system’s 10-point scale (10 being most destructive). His conclusion was based on the fact that the ground motion identified by GPS indicated the slip of the fault transferred fairly minimal kinetic energy to the ocean.

“We were fortunate to have a station sufficiently close to the epicenter,” delivered Yoaz Bar-Sever, JPL manager of the GDGPS system. “Broad international collaboration is required to densify the GPS tracking network so that it adequately covers all the fault zones that can give rise to large earthquakes around the world.”

Coastal areas in the Cascadia Region are at risk for tsunamis - like the tsunami that ravaged communities around the Indian Ocean after a great earthquake on Dec. 26, 2004. Tsunamis on Cascadia are not recurrent but could arise either from a large earthquake on the Cascadia Subduction Zone, or from a distant earthquake strong enough to send a tsunami across the ocean. Tsunami Escape Route signs have been mounted on the coasts of Alaska, Hawaii, Washington, Oregon, Alaska and California.

Although tsunamis do not occur frequently, they can cause a tremendous amount of damage in coastal areas when they do occur. The National Tsunami Mitigation Program offers a coordinated national effort to assess tsunami threat, prepare community response, issue timely and effective warnings, and mitigate damage. Tsunami Warnings for the Cascadia coast are spawned by the Alaska Tsunami Warning Center.

Every state in the Cascadia Region has issued a brochure warning people of the danger of tsunamis and what they can do to avoid being killed by one. These brochures are connected in the mitigation section of this site. Some useful information about tsunamis is available from the Oregon State brochure about tsunamis and is reproduced below. This information applies to all coastal areas in the Cascadia Region. Surviving a Tsunami—Lessons from Chile, Hawaii, and Japan is a USGS pamphlet about well-documented tsunami events in numerous countries.

A tsunami is not just one giant wave, but a set of waves with an extremely long wavelength and period. These waves commence by dispersing energy from displaced water outwards.

Near the source of energy, a tsunami can have wavelengths larger than 300 miles long with periods as long as an hour. Typically, the wavelength and period amplify proportionally to the depth of the water. One period is the time between two waves. Due to the great length of the waves, tsunamis behave as shallow water waves, in the sense the ratio between the water depth and wavelength is very small. In deep water, tsunamis are able of traveling at very high speed. The acceleration of a tsunami is the product of the acceleration of gravity multiplied and the water depth. A tsunami in the Pacific Ocean can travel at speeds up to 450 mph, over half the speed of sound.

As the waves move toward the shore, the depth gradually decreases, decelerating the tsunami. However, due to the conservation of energy, the waves are enforced to grow taller until reaching heights between 30 and 100 feet. Some of the energy is lost to friction and turbulence, but the waves still have a large amount of energy and can reach many feet inland.

On the night of July 9, 1958 an earthquake all along the Fair-weather Fault in the Alaska Panhandle loosened about
40 million cubic yards (30.6 million cubic meters) of rock high above the northeastern shore of Lituya Bay.

This mass of rock thrust from an altitude of approximately 3000 feet (914 meters) down into the
waters of Gilbert Inlet (see map below). The impact produced a local tsunami that crashed against the southwest shoreline of Gilbert Inlet. The wave strike with such power that it swept completely over the spur of land that separates Gilbert Inlet from the main body of Lituya Bay.

The wave then persisted down the entire length of Lituya Bay, over La Chaussee Spit and into the Gulf of Alaska. The force of the wave eliminated all
trees and vegetation from elevations as high as 1720 feet (524 meters) above sea level. Millions of trees were deracinated and swept away by the wave. This is the highest wave that has ever been known.

Most people think that there is no difference between a tidal wave and a tsunami, and often use the words interchangeably. This is inaccurate, and while both of the waves carry the power of devastation, the greatest difference is how each is born.

A tidal wave is directly forced by the atmosphere. The correlating factors between the sun, moon, and Earth cause a annoyance in the sea, and a ’shallow water wave’ is formed. Shallow water waves imply that the development of a tidal wave is much closer to the shoreline of a land mass that will ultimately be in its path. However, because of the depth relating to it origins, it is possible that a tidal wave can ‘burn itself out’ before it reaches the land.

The origin of the tsunami is much deeper. It is caused by a deep disturbance along the ocean floor. This disturbance usually comes from an underwater earthquake, or even an underwater landslide. The deeper origin of the tsunami creates a more emphatic wave. It will often carry itself across hundreds, or even thousands, of miles of ocean before making landfall.

The data, collected using a commercial ship, reveals the structure of Earth’s crust below the Nankai Trough, which is known to generate destructive tsunamis.The Nankai Trough is in a subduction zone, where two tectonic plates are colliding and pushing one plate down below the other. The grinding of one plate over the other in subduction zones leads to several world’s largest earthquakes.Using the 3D seismic images, researchers restructured how layers of rock and sediment have cracked and shifted over time.

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This research helped them to find two things that contribute to large tsunamis.First, they validated the existence of a major fault that runs from a region known to unleash earthquakes about 10 kilometers (6 miles) deep right up to the seafloor. When an earthquake happens, the fault allows it to reach up and move the seafloor up or down, bearing a column of water with it and setting up a series of tsunami waves that extend outward.

Secondly, the team discovered that the recent fault activity, maybe including the slip that caused the 1944 event (which killed 1200 people), has shifted to landward branches of the fault, becoming shallower and steeper than it was in the past.“That leads to more direct dislocation of the seafloor and a larger vertical component of seafloor displacement that is more effective in generating tsunamis,” said Nathan Bangs, superior research scientist at the Institute for Geophysics at The University of Texas.

A strong earthquake with a magnitude of 7.5 struck in the ocean near India’s Nicobar Islands recently, sparking some tsunami warnings, the U.S. Geological Survey and local officials said.There were no initial reports of fatalities or damage, although people ran from their homes in fear on Nicobar, witnesses said.

the USGS said in a statement.

The quake was originally recorded with a magnitude of 7.7 but that figure was later revised down slightly to 7.5,

The Pacific Tsunami Warning Center in Hawaii in the beginning issued a regional tsunami watch that was put in effect for all areas of the Indian Ocean, including India, Indonesia, Sri Lanka, Myanmar, Thailand and Malaysia. The warning was shortly revised down to cover India only and was then cancelled for all areas.

It may be several months or years before the Chilean tsunami is accurately understood.

But there are various other reasons why so many fewer people lost their lives this weekend.One is preparedness. Having suffered a destructive tsunami following a magnitude 9.5 earthquake in 1960 — the largest earthquake ever recorded — Chileans knew what was coming. Reports specify that alarms were sounded in the town of San Juan Bautista on Robinson Crusoe Islands, for example, possibly saving hundreds of lives.

That preparedness is also returned in Chile’s building codes, another lesson of the 1960 quake. Strong buildings likely conserved thousands of lives and prevented this disaster from approaching the magnitude of the continuing horrors in Haiti.

The size and depth of the Pacific Ocean may also have been a feature.Tsunami experts spot out that if a fault ruptures in relatively shallow water, the energy pulse may weaken as it emanates out into the deep ocean.This may have been the case with the Chile quake. It’s also possible that the fault moved somewhat horizontally, reducing the amount of vertical displacement in the water.