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.
Tribal Conflict Has Devastated Papua New Guinea
“My people, my land. You don’t know how much it’s hurting me”. 25 years ago in Papua New Guinea a violent conflict erupted in the coffee-growing plantations. Is the Ganiga tribal war finally over?
For similar stories, see:
The Student Protest Bringing Papua New Guinea To A Standstill
The Resource Crisis Fuelling Conflict in Papua New Guinea (2010)
With The Army in Papua New Guinea’s Upheaval (1997)
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“This valley was a war zone. And now I’ve come back to find out what happened after I left.” Bob Connolly returns to Papua New Guinea where in 1992 he recorded shocking scenes of violence between coffee harvesters depicted in Black Harvest. Coffee prices have climbed again, but the problems of the past still manifest in a region scarred by the divisions of modern and ancient laws.
ABC Australia – Ref.6898
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