Tsunami Warning Centers , which work in conjunction with USGS seismic networks to help determine when and where to issue tsunami warnings. If an earthquake meets certain criteria for potentially generating a tsunami, the pop-up window and the event page for that earthquake Could a large tsunami happen in the United States? Large tsunamis have occurred in the United States and will undoubtedly occur again.
Significant earthquakes around the Pacific rim have generated tsunamis that struck Hawaii, Alaska, and the U. One of the largest and most devastating tsunamis that Hawaii has experienced was in from an earthquake along the Aleutian subduction Filter Total Items: 8. Year Published: Reducing risk where tectonic plates collide—U. Geological Survey subduction zone science plan The U.
Gomberg, Joan S. View Citation. Gomberg, J. Geological Survey subduction zone science plan: U. Geological Survey Circular , 45 p. Jones, Jamie L. Attribution: Western Geographic Science Center. Jones, J. Geological Survey Scientific Investigation Report —, 32 p. Year Published: The Great Alaska Earthquake and tsunamis: a modern perspective and enduring legacies The magnitude 9. Brocher, Thomas M. Ostbo, Bruce I. Year Published: Community exposure to tsunami hazards in California Evidence of past events and modeling of potential events suggest that tsunamis are significant threats to low-lying communities on the California coast.
Wood, Nathan J. Year Published: Tsunami hazards— A national threat In December , when a tsunami killed more than , people in 11 countries around the Indian Ocean, the United States was reminded of its own tsunami risks.
Year Published: Tsunamis — Scourge of the Pacific Although tsunamis occur most often in the Pacific Ocean, they can be generated by major earthquakes in other areas. Lockridge, Patricia. Filter Total Items: 6.
Date published: March 5, Date published: February 1, Date published: September 18, Attribution: Science Application for Risk Reduction. Date published: September 17, California Prepares for Someday's Bigger Tsunami. Date published: August 20, Date published: September 5, Filter Total Items: List Grid. February 1, January 26, As a result, they can traverse the entire Pacific Ocean in less than 24 hours. A tsunami is forced to slow down only when it approaches the coast.
Unfortunately, this is when it becomes dangerous! Near to shore, the deep-ocean floor rises to meet the beach. When the front of the tsunami reaches this shallow area, the friction created by the water climbing over the rising ocean floor slows the water in the leading edge of the wave. Meanwhile, the back of the wave may be many miles behind in deep water—still traveling at great speed, as are the waves to come. This slowing of the leading edge of the first wave triggers a "pileup"—not unlike that seen when a car suddenly slows on a crowded highway.
The rest of the wave, and perhaps the wave behind it, bunch up. The water has nowhere to go but up. Some of the most massive tsunamis rear 30 feet 9 meters or more above the surface of the water. There have even been historical reports of tsunamis more than feet 30 meters high—as tall as a story building!
By the time it hits shore, a tsunami may have slowed to as little as 30 miles 48 kilometers per hour. What it lacks in speed, it makes up for in power. A typical tsunami may dump more than , tons of water per 5 feet 1. It can spread its water arms 1 mile 1. This vulnerable coastal area is called the inundation zone.
Tsunamis typically do the most damage in the coastal zones that lie closest to their place of origin—within 30 to 60 minutes of tsunami-travel time. If the epicenter of the earthquake is close enough to shore that shaking is actually felt, any resulting tsunamis will hit within seconds or minutes. The moments just before a tsunami hits can be a time of eerie calm. In some places, the water begins to slowly but surely rise.
In others, the water actually pulls back from the coast. In some instances, harbors and bays are entirely emptied of their water. This happens if the trough of the wave is traveling ahead of the crest. The temptation to explore such a bared ocean floor can be deadly. Such was the case when crowds of curious onlookers walked into the emptied harbor of Lisbon, Portugal, before a tsunami hit in ; and again off the shore of Hilo, Hawaii, in A much wiser move would have been to run to high ground as far inland as possible.
But escape is not always possible. In , tsunami waves crashed into the front of an Indonesian island, split in two to wrap around the island, and then recombined to destroy two villages on the supposedly safe leeward side. Tsunami Safety The power of a tsunami is the stuff of legend. Some people believe that a tsunami wiped out the mythical city of Atlantis. Another theory holds that it was the initial harbor-emptying phase of a tsunami that was the real force behind Moses' parting of the Red Sea.
It has even been suggested that giant tsunamis—spawned from a gigantic asteroid impact—helped to kill off the world's dinosaurs. Despite modern technology, humans are not much better off than the dinosaurs when it comes to avoiding tsunamis.
The only thing people can do is get out of their way, and fast! Many coastal communities—especially those along the Ring of Fire—have developed tsunami evacuation plans. Their aim is to shepherd people off beaches and low-lying coastal areas and onto higher ground. Crucial to any such plan is an early-warning system. The Pacific Tsunami Warning Center was built in It collects seismic data from 26 member countries and a number of other nonmember participants via satellite, and keeps watch 24 hours a day for any suspicious shaking that might trigger tsunamis.
A second warning center, in Palmer, Alaska, studies local seismic activity that could trigger tsunamis heading toward the coasts of British Columbia, Washington, Oregon, and California. When seismometers detect a quake of magnitude 7. Tsunami waves in the deep ocean can travel at high speeds for long periods of time for distances of thousands of kilometers and lose very little energy in the process.
The deeper the water, the greater the speed of tsunami waves will be. At such high speeds, a tsunami generated in Aleutian Islands may reach Hawaii in less than four and a half hours.
In , great tsunami waves generated in Chile reached Japan, more than 16, km away in less than 24 hours, killing hundreds of people. Current Warnings Most Recent Tsunami. Also Tsunami Sources Icosohedron Globe. What to Do?
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