Open to the sea, Alaska's Pacific coastal communities are vulnerable to one of nature's greatest threats -- tsunami.
Once a devastating bolt-out-of-the-blue phenomenon, the arrival of the hugely destructive waves can be predicted now, and residents living in low-lying areas often can be given hours of notice -- time enough to evacuate if necessary.
A bit of that early-warning technology was installed in Homer on Thursday for demonstration purposes. Technicians from the Tsunami Warning Center in Palmer installed a satellite dish and software designed primarily to give emergency managers rapid, up-to-date weather information.
In Homer's case, however, the equipment also will be used to provide early warning of tsunamis that might threaten this seaside community, said Homer Fire Chief Robert Painter.
The equipment and software were installed at the Homer Police Station, site of the city's emergency dispatch operators. The station is tied by cable to Homer's fire station.
Called RealEMWIN, for Real Emergency Managers Weather Information Network, the software was developed by a company called Skywatch Services to assist in downloading and displaying weather wire data transmitted over the nationwide weather information network. Available within seconds are everything from local weather conditions and forecasts to severe weather watches and warnings, including satellite and radar graphics.
The system already has been installed at the Alaska State Troopers post in Soldotna and is tied into the Kenai Peninsula Borough Office of Emergency Management and the Seward Fire Station.
In Alaska, the system transmits data via the GOES West satellite, but the system also can use VHF radio reception and the Internet with the appropriate software. RealEMWIN also is available to the general public for use on home computers.
For Homer, permanent installation of such a satellite data system would give the city one more way to receive early warnings.
Homer is trying to become a TsunamiReady Community, under a program of the National Weather Service. While not necessary for the federal application, demonstrating that the city has redundant systems for handling emergencies won't hurt the effort to earn that designation, Painter said.
The TsunamiReady Community program's aim is to upgrade the readiness of Alaska coastal villages, towns and cities. The program also is under way in Washington, Oregon, California and Hawaii.
"For us, the effort began just last year," Painter said. "We had known about the program for a year or so. Then I got some more information at an emergency managers conference last year and found out we were a lot closer (to the designation) than we'd thought."
Painter said the city should have the final version of the application next week.
The effects of a tsunami, how big they might be and how much territory they might inundate still cannot be precisely predicted, though scientific efforts have led to several modeling schemes now being applied to various Pacific shorelines in an effort to be as accurate as possible.
"It's a young science yet," said Alec Medbery of the Tsunami Warning Center.
Tsunamis are caused when a disturbance such as an earthquake displaces the water column vertically. The waves also can be generated by landslides, as with volcanic eruptions, or even by meteors crashing into the sea.
According to studies, the deeper the water, the faster a tsunami will travel. On average, a tsunami may cross the Pacific Ocean at speeds between 450 and 650 mph, faster still in the very deepest parts of the ocean. That compares to the turtle's pace of a wind-generated ocean wave, which will roll along at a leisurely 10 to 20 mph.
In the deep ocean, the distance between wave crests may stretch over hundreds of miles causing a rise in the ocean surface measurable only in inches. Thus, passing tsunamis are virtually undetectable except by specialized equipment. A ship's crew far from shore might never notice one beneath the hull.
Once a wave nears shore, however, the physics change. As the ocean depth rapidly decreases, the energy of the wave forces the surface skyward, creating the classic near-shore waveform that can rush inland with devastating impact.
On June 15, 1896, a tsunami never noticed by fishers miles offshore, struck the port of Sanriku on northern Honshu without warning. The wave, by some accounts 100-feet high, killed 28,000 people and devastated 170 miles of coastline. Ten and a half hours later, an east-traveling wave generated by the same offshore quake reached San Francisco, 5,000 miles away.
Medbery, who was accompanied by another warning center employee, Michael Burgy, said the system could provide a constant stream of data on a "crawler," a moving reader board along the bottom of the screen, as well as audible alarms to alert emergency personnel that critical data is coming in.
Painter is anxious to have the system up and running. Relying on landlines, radio or even the Internet can be problematic in a severe storm or after an earthquake, he said.
"Our connections are tenuous at best in Alaska," he said. In a big earthquake or severe storm, the Internet would likely be the first system to go down because it depends on cable connections that could be damaged, Painter said.
Satellites aren't damage-proof either. Magnetic solar storms several years ago knocked out the only satellite then being used by the U.S. Geological Survey in Colorado, Medbery said.
The demonstration system will be operating for a couple of weeks at least. Homer will then decide about investing in such equipment. If the software is to the city's liking, permanent installation would relatively inexpensive -- roughly $1,000, according to Medbery.
About the only thing Homer still needs to qualify for the Tsunami-Ready Community program are a shipment of brochures soon to be printed that will provide information to the general public about tsunamis. They will include appropriate evacuation routes for the Homer area, Painter said.
While parts of downtown Homer, including at least one of its schools, lie low enough to be considered in danger from a tsunami, it is the 4.5-mile-long Homer Spit that is of greatest concern to emergency managers. The finger of land is home to the city's port and harbor and dozens of businesses related to the tourist and fisheries industries. There is but one way off and evacuation could be difficult, especially during the busy summer months, Painter said.
While Homer's location well inside Kachemak Bay provides some protection, ocean-traveling tsunamis could still cause problems there, Medbery warned.
Of greater concern, however, is a tsunami generated by a local quake or volcano. Homer and the rest of Southcentral Alaska sit on an active tectonic plate boundary subject to frequent quakes and volcanic eruptions.
Topping the list of potential local dangers to Kachemak Bay communities is Augustine Volcano roughly 70 miles west of the mouth of Kachemak Bay on the far side of Cook Inlet. Augustine is among the most active of a chain of volcanoes along the Alaska Peninsula. It is of the same general type as Mount St. Helens in Washington and prone to the same kind of dramatic events, including collapsing flanks that could send huge landslides into the inlet.
Such a collapse could generate a tsunami aimed right down the throat of Kachemak Bay. Due to the relative shallowness of the inlet, the wave would not propagate as quickly as one in the deep ocean, but it still would reach the Homer Spit in an hour or two, according to studies, Painter said.
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