Tsunamis - Could they happen here?

The recent tsunami which struck much of Southern Asia left a path of destruction, and with it, many questions in its wake.

Along with expressing our concern for the millions that are affected by the tsunami, many here are asking questions ranging from “What is a tsunami?”, and “How can I help?”, to “Could this happen here?”

First, a tsunami is a series of ocean waves generated by any rapid large-scale disturbance of the sea water. Most tsunamis are generated by earthquakes, and are generated by vertical movement of the sea floor.

The South Asia tsunami was caused by undersea tectonic or earthquake activity near the convergence of the India and Burma tectonic plates. This is a subduction zone with the India plate overridden by the Burma plate.

This area shares some similarities with the San Juan Islands. But there are also some major differences in the contributing circumstances. The main similarity is that we live near a tectonic plate boundary. The major differences are that we have a well developed and effective warning system available, preparedness programs and education, and very different terrain. This gives us time for escape from high waters.

San Juan County lies near the convergence of the Juan De Fuca and North American plates. This area forms the Cascadia Subduction Zone, an area of active plate boundaries, along which movement occurs. At times, this results in earthquakes, which may in turn generate tsunamis.

Indeed, San Juan County is vulnerable to a tsunami after a large Cascadia subduction zone earthquake. Computer modeling completed by the State Department of Natural Resources for the Puget Sound region suggest a maximum wave height on the order of three meters, or about 10 feet. This would be higher at the head of an inlet, possibly 20 or more feet. Areas affected by such a surge would be waterfront with low, or no bank. The closer to the high tide level that you are, the more you might be affected by a tsunami.

The similarities between San Juan County and the Southeast Asian crisis end there. One reason already identified as a major contributing factor to the losses is the fact that the Indian Ocean has no tsunami warning system. According to recent reports, the potential for the tsunami had been identified after the earthquake. However, there was no system to spread a warning, which tragically left so many in harm’s way.

The Pacific Northwest and San Juan County are fortunate to be served by the National Oceanic and Atmospheric Administration's West Coast & Alaska Warning Center, which has the responsibility for generating tsunami warnings. This center is part of the National Oceanic and Atmospheric Administration (NOAA) and was established in 1967.

If there is a threat of tsunami, you would hear about it based on a warning system. A warning would be issued to coastal areas such as ours, following any coastal earthquake that has a magnitude of 7.1 or greater. Warnings are issued within 15 minutes after an earthquake occurs. These types of warnings are sent through the National Warning and Alert System, to the San Juan County 911 dispatch center. Warnings are also sent through the NOAA weather radio alert system.

Residents who use NOAA Weather Alert Radios, that have the new Specific Area Message Encoding (SAME) alert feature, can receive these and other warnings for this area directly from NOAA. These radios are available from Radio Shack locally for about $50. You can also tune into local radio and television stations, which will relay warnings.

Many of the tsunami-devastated areas have little or no elevation change from sea level. Here, we don’t have to go very far to get to high ground. Our rule of thumb is if there is an earthquake strong enough to knock you down, go to high ground and stay there until any danger is known to have passed. Tsunamis come in a series of waves. There may be other signs such as a rapid lowering of the sea level. If this happens, we need to move inland, to safety.

We can help to protect ourselves by following preparedness guidelines such as those in mailings sent by the Orcas Island Fire Department and county Emergency Management. These can also be found on the County DEM website www.sanjuandem.net. Simple steps that we might take now may yield tremendous benefits for our loved ones and community.

You may be one of the many who would like to reach out to the global community to offer help to those mourning and recovering from their tsunami losses. It is certainly difficult and frustrating when we see so clearly the devastation and yet it is so far away. As is the case with most disasters, the best way for us to help is to provide monetary support to a charitable organization participating in the relief effort.

As the year 2004 comes to a close and many of us are looking for a new resolution to greet the New Year, why not make it one of preparedness? It's not as hard as some of the others, and the benefits will last a lifetime.

For more information contact Brendan Cowan, director of the San Juan County Department of Emergency Management, at 378-9932, or me, Dave Halloran, assistant emergency manager, at 376-6014.

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