Gordon Gumpertz asked:
Can a tsunami strike the coast of New Jersey, North Carolina, or Florida? The question crossed my mind as I was doing research for my action/adventure novel TSUNAMI, even though the book is set in the Pacific.
The answer is yes, a tsunami hitting the Atlantic Coast is possible, but much less likely than one striking Alaska, Hawaii, or the Pacific Northwest. When it comes to the kinds of natural events that start tsunamis — undersea earthquakes, submarine landslides, and volcano eruptions — the Atlantic is a much tamer ocean than the Pacific. The Pacific basin is encircled by the notorious Ring of Fire with its hundreds of active volcanoes and dozens of dangerous, earthquake-prone subduction zones. The Atlantic has far fewer geological areas capable of posing a genuine tsunami threat. But there are some, and they should be taken seriously.
The one most talked about is the Cumbre Vieja volcano in the Canary Islands, 3000 miles from Boston and 3700 miles from Miami. In 1949, a flank of the volcano split off, creating a 3-ft. rift, the flank sliding down 3 feet toward the ocean before it stabilized. Earthquakes and a buildup of pressure inside the volcano were associated with the event. The concern is that another earthquake or eruption could dislodge the entire flank and send as much as 300 cubic miles of debris plunging into the ocean. One school of thought suggests that such a monster landslide would start a tsunami capable of reaching the eastern seaboard of the United States 5 or 6 hours later.
Even if such an event were to happen, many geologists dispute the notion that it would send a killer tsunami smashing into the East Coast of the U.S. The height of the initial wave would be enormous, but the length between waves would be relatively short, meaning its ability to maintain its energy while travelling long distances would be minimized. Undersea earthquake-generated tsunamis typically have long wavelengths, or distance between waves in the train, and can travel long distances without significant loss of energy. In contrast, landslide-initiated tsunamis tend to have short wavelengths and are usually confined to local areas where they can be highly destructive. In 1883, the Krakatau eruption dumped millions of tons of debris into the ocean and started a 135-ft. tsunami that did incredible damage to Sumatra and neighboring islands but did not affect other areas.
To sum it up, there are two points of view. One maintains the collapse of a chunk of Cumbre Vieja into the ocean could endanger the Atlantic Coast of the U.S. with a major tsunami, while the other view holds that the dynamics of wave formation make such a result unlikely.
The only true subduction zone close to the East Coast is the Puerto Rico Trench, which runs for 1000 miles from Puerto Rico eastward past the Lesser Antilles and out into the Atlantic Ocean. The deepest point in the Atlantic at 28,200 feet lies in The Puerto Rico Trench. Along this trench, the Caribbean tectonic plate is subducting, or sliding under, the North American Plate. This is not as large or active a subduction zone as most of those in the Pacific, but undersea earthquakes have occurred there, resulting in tsunamis that affected the islands in the Caribbean. The last tsunami in the area happened in 1918 when 32 people died in Puerto Rico and the Virgin Islands.
Mt. Pelee on Martinique is one of several active volcanoes in the Lesser Antilles arc. The 1902 eruption of Mt. Pelee is one of the largest on record. It is possible that volcanic debris from future eruptions could crash into the ocean and start a localized tsunami.
Submarine landslides at the edge of the continental shelf along the Atlantic Seaboard might also start tsunamis that could impact coastal cities. In 1929, a 7.2 magnitude earthquake off Newfoundland started an undersea landslide down the continental shelf. The resulting tsunami swept ashore and killed 8 people.
The Atlantic Tsunami Warning System was installed in 2006, comprising five Deep Ocean Assessment and Reporting of Tsunami (acronym DART) buoy stations. Single stations are located off Charleston, Miami, and New Orleans. Two are positioned off Puerto Rico near the Puerto Rico Trench. All provide real time detection of undersea disturbances capable of starting tsunamis that could impact the Atlantic, Caribbean, and Gulf Coasts. Plans call for the addition of at least two more DART stations.
If you live in a low-lying area on the Atlantic Coast, be aware that a tsunami is always a possibility, and be prepared to evacuate on a moment’s notice as directed by local authorities.
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Posts Tagged ‘Undersea Earthquake’
Can a Tsunami Strike the Atlantic Coast?
Tuesday, September 23rd, 2008Tags: Active Volcanoes, Adventure Novel, Alaska Hawaii, Cubic Miles, Cumbre Vieja Volcano, Dangerous Earthquake, Eastern Seaboard, Geological Areas, Initial Wave, Killer Tsunami, Long Distances, Ocean One, Pacific Basin, Pacific Northwest, Subduction Zones, Submarine Landslides, Tsunami Threat, Undersea Earthquake, Undersea Earthquakes, Volcano Eruptions
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Tsunami Warning System – Will it Give You Time to Escape?
Sunday, December 17th, 2006Gordon Gumpertz asked:
The amount of warning time a tsunami warning system can provide depends on the distance between your location and the location of the undersea event. A tsunami can travel 500 to 600 mph in deep water, slowing as it approaches shore. If the undersea earthquake that starts the tsunami is 500 miles offshore in deep water, for example, and the tsunami is headed your way, local authorities will be notified within minutes of the event and will have about one hour to issue the warnings to the public and start announcing directions for evacuation to a safe area.
In doing research for my adventure novel TSUNAMI, I found that in some cases, a local earthquake or undersea landslide close to shore can initiate a tsunami that strikes almost without warning. In 1998, a 7.0 magnitude undersea earthquake near Papua, New Guinea, triggered a massive submarine landslide that started a 50-ft. tsunami close to shore. The wave hit the shoreline within minutes and wiped out several villages along the New Guinea coast, stripping the land almost bare. 2200 people died.
However, most major tsunamis are started by undersea earthquakes in deep water. In the Pacific Ocean, a quake will be picked up by seismometers, pressure sensors, and tidal gauges at the reporting stations of the Pacific Tsunami Warning System operated by 26 nations bordering the Pacific Basin. The collected data registers on the instruments at the Pacific Tsunami Warning Center in Ewa Beach, Hawaii. The scientists at the Ewa Beach warning center can then determine the location, earthquake magnitude, tidal variations, and changes in ocean pressure. If readings indicate the disturbance may have started a tsunami, warnings are issued immediately to the areas in danger with approximate arrival time of the first wave.
If an undersea event happens near Alaska or anywhere along the West Coast of the U.S., the instrument signals are picked up by the West Coast & Alaska Tsunami Warning System headquartered in Palmer, Alaska. There the same procedure is followed. Immediate warnings are issued to local authorities in the areas at risk.
As part of the international tsunami warning network, the United States has recently completed its own U.S. Tsunami Warning System that takes in the Pacific Tsunami Warning System, the West Coast & Alaska Tsunami Warning System, and the Atlantic Tsunami Warning System. The U.S. system is composed of 39 DART (Deep Ocean Assessment and Reporting of Tsunami) and DART II stations. Five stations are located in the Atlantic, Caribbean, and Gulf of Mexico, and the remaining 34 in the Pacific. The DART system is made up of a pressure sensor resting on the ocean bottom that transmits continuous data by acoustic telemetry (sound waves) to a surface buoy anchored near the pressure sensor. The buoy is equipped with satellite link that relays the real time information to tsunami warning centers around the world. Certain fluctuations in ocean bottom pressure can indicate the presence of a tsunami.
Many other kinds of reporting stations and observatories are used in the larger international reporting network. These include pier-based and satellite-based tidal gauges that track the height and length of passing tsunami waves, and seismometers buried in ocean bottom caissons that measure the magnitude of an undersea earthquake and determine its location.
One of the most well known undersea seismometer projects is the Hawaii2 Observatory (H2O) located in deep water between Hawaii and California. The observatory was placed next to a retired undersea AT&T telephone cable so that the cable could be used to power the observatory. The observatory package includes a broadband seismometer, geophone, hydrophone, and pressure sensor developed by the Woods Hole Oceanographic Institution and the University of Hawaii.
The installation was performed by ROVs (remotely operated submarine vehicles) controlled from a mother ship. The ROVs drilled a borehole, sunk a caisson into the hole, then inserted the seismic package into the caisson and sealed it. The seismic package is connected to an adjacent junction box operated with 400 watts of power fed from the old telephone cable. The sensor information is transmitted by fiber optic cable to a relay station on a surface buoy, which sends the data to the internet so that it can be used by tsunami warning centers and by universities and scientific laboratories around the world. The H2O installation has had many problems and has never performed up to expectation. However, the overall tsunami warning system works well. The entire system has undergone successful testing.
If you live on or near the beach and if your local authorities issue a tsunami warning, take it seriously and follow evacuation directions. Do not hang around the shoreline to watch the tsunami. It could cost you your life, because the wave can be up to 100 feet high and moves much faster than a person can run.
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Tags: Adventure Novel, Alaska Tsunami Warning, Approximate Arrival Time, Earthquake Magnitude, Ewa Beach Hawaii, Guinea Coast, Ocean Pressure, Pacific Tsunami Warning, Pacific Tsunami Warning Center, Pacific Tsunami Warning System, Papua New Guinea, Pressure Sensors, Submarine Landslide, Tidal Variations, Tsunami Warning Center, Tsunami Warning System, Tsunami Warnings, Undersea Earthquake, Undersea Earthquakes, Undersea Landslide
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