Acehtsunami

The PacificTsunami Warning Center is one of two tsunami warning centers that are operated by NOAA in the United States of America.

Headquartered in Ewa Beach, Hawaii, the PTWC is branch of an international tsunami warning system (TWS) program and serves as the operational center for TWS of the Pacific issuing bulletins and warnings to participating members and other nations in the Pacific Ocean area of responsibility.

It is also the regional (local) warning center in the State of Hawaii.The various other tsunami warning centers is the West Coast and Alaska Tsunami Warning Center (WCATWC) in Palmer, Alaska, serving all coastal regions of Canada and the United States except Hawaii.

Earthquake with a preliminary magnitude of 5.7 strike the Caribbean island of Puerto Rico early Sunday, the U.S. Geological Survey said.

The quake hit at 1:16 a.m. (0516 GMT) four miles (six kilometers) from the small community of Espino on the western part of the island and 63 miles (101 kilometers) from the capital, San Juan. It was recorded at a depth of 68 miles (110 kilometers).

There were no immediate reports of damage and injuries.

The West Coast and Alaska Tsunami Warning Center said it did not guess a tsunami, but local tsunamis triggered by underwater landslides were possible in coastal areas close to the epicenter.

Tsunamis are different from wind-generated waves, which many of us may have observed on a local lake or at a coastal beach, in that they are characterized as shallow-water waves, with long periods and wave lengths.The wind-generated swell one sees at a California beach, for example, seeded by a storm out in the Pacific and rhythmically rolling in, one wave after another, might have a period of about 10 seconds and a wave length of 150 m.

A tsunami, on the other hand, can comprise a wavelength in excess of 100 km and period on the order of one hour.

As a result of their long wave lengths, tsunamis usually behave as shallow-water waves.A wave becomes a shallow-water wave when the ratio between the water depth and its wave length gets very less.Shallow-water waves travel at a speed that is equal to the square root of the product of the acceleration of gravity (9.8 m/s/s) and the water depth.

If the first part of a tsunami to reach land is a trough known as drawback, rather than a wave crest. The water along the shoreline recedes dramatically, exposing usually submerged areas.

A drawback generally occurs because the tectonic plate on one side of the fault sinks suddenly during the earthquake, causing the overlaying water to propagate outwards with the trough of the wave at its front. This is why there would not be any drawback when the tsunami traveling on the other side arrives ashore, as the tectonic plate is “raised” on that side of the fault line.

Drawback starts to begin before the wave arrives at an interval equal to half of the wave’s period. If the slope of the coastal seabed is small, drawback can exceed about hundreds of meters. People who are unaware of the danger sometimes remain near the shore to satisfy their curiosity or to collect fish from the exposed seabed. During the Indian Ocean tsunami, the sea withdrew and a number of people went onto the exposed sea bed to investigate. Photos show people walking on the normally submerged areas with the advancing wave in their background.

It has been planned and designed as a symbolic reminder of the disaster, as well as an educational centre. In addition it will also serve as an Emergency disaster shelter in case the area is ever hit by a tsunami again.

Aceh served as home for more than half the 240,000 people who died in the disaster. The outburst of aid which followed was the largest in history. Almost all that aid money has now been spent - gone to pay for more than 130,000 houses and thousands of kilometers of road, bridges, as well as schools, and other infrastructure.

Yet this new museum building, paid for by Ache’s Reconstruction Fund, breaks with the tradition of post-disaster construction.

Tsunamis can be generated when the sea floor hurriedly deforms and vertically displaces the overlying water. Tectonic earthquakes are a certain kind of earthquake that are associated with the earth’s crustal deformation; when these earthquakes occur beneath the sea, the water above the deformed area is relocated from its equilibrium position.

Waves are formed as the displaced water mass, which acts under the pressure of gravity, attempts to regain its equilibrium. When large areas of the ocean floor elevate or subside, a tsunami can be created. Huge vertical movements of the earth’s crust can occur at plate boundaries.

Plates act together along these boundaries called faults. Around the margins of the Pacific Ocean, for instance, denser oceanic plates slip under continental plates in a process known as subduction. Subduction earthquakes are mainly effective in generating tsunamis.

In general, if you think tsunami is going to hit or the ground shakes under your feet or you hear there is a warning, you should move immediately to higher ground.

If you are at home and hear there is a tsunami warning, you should make sure people around you are also aware of the warning. You should quickly move to a safer place if you live in an evacuation zone. Follow the guidance of local emergency and law enforcement.

If you are at the beach or anywhere near the ocean and you feel the ground shake, move immediately to higher ground; DO NOT wait for a warning to be announced. Stay away from rivers and streams that lead to the ocean so that you would stay away from the beach and ocean. A regional tsunami from a local earthquake could smack some areas before a tsunami warning could be announced.

Tsunamis generated in distant locations will generally give a time lapse so that people can move to higher ground. For locally-generated tsunamis, where you might feel the ground shake, you may only have a few minutes so you should react sooner and move to higher ground.

A huge glacier has broken off and forcedly submerged into a lake at , sparking a 23-meter high tsunami wave which completely destroyed a nearby town.

The massive chunk of ice –termed as Hualcan glacier, it was around the size of four soccer fields — tumbled into the ‘513 lake’ in the Andes near Carhuaz, around 200 miles north of Lima.

According to the Indeci civil defense institute, 50 homes were destroyed. A water processing plant serving 60,000 local residents was also destroyed when the wave struck on Sunday.
At first, six people were reported missing, feared dead under the debris — but local governor Cesar Alvarez has said five of those have been found alive. Authorities discharged mountain valleys, fearing more ice breakage after the tsunami, which are most commonly caused by earthquakes.

A 6.0-magnitude earthquake occurred Friday afternoon under the Bering Sea, but officials say it posed no tsunami risk and was too far away to be felt on land.

David Hale at the West Coast and Alaska Tsunami Warning Center in Palmer, Alaska, says the quake at 3:12 p.m. Alaska Daylight Time was followed 4 minutes later by a 6.0 magnitude aftershock. The quakes were centered about 480 miles southwest of Nome and about 9.8 miles deep.

Hale says people at a National Weather Service station on St. Paul Island, about 400 miles southeast of the epicenter, report they didn’t feel anything.