The Seward Phoenix Log - News of the Eastern Kenai Peninsula since 1966

By Heidi Zemach
For the LOG 

Time and speed is of the essence

 

"There will probably be some beachfront that disappears, more than likely of a similar nature to the '64 quake. There may be infrastructure on that beachfront that disappears. There will also be significant wave run up if that occurs; tsunami inundation all over again," said Dan Mahalak, a hydrologist, whose official title is Water Resource Manager for Kenai Peninsula Borough. He has been on the Alaska Seismic Hazard Safety Commission, and is well aware of the Seward studies on the risk and effects of possible future earthquakes and tidal waves.

"So be prepared to be on your own for a while," Mahalak said. He hopes most people will stock themselves with enough food, water, and fuel sources to survive for an extended period of time without power, telecommunications or grocery stores. Flood insurance also is available that would cover tsunamis, he said. But most important of all, "If the ground starts shaking, the chance of a tsunami occurring is going to be prevalent. In other words, don't wait for sirens to go off, or for the offshore tsunami warning to sound. By the time sirens go off there will more than likely already be locally-generated waves."

The predicted tsunami run-up inundation areas that could be affected include the Lowell Point community, Fourth of July and Seward Marine Industrial Center, Small Boat Harbor area, Seward Waterfront Park, Port Avenue, Alaska Railroad dock, and the first few city blocks along all shorelines of Resurrection Bay. In certain predictions, and also a '64-repeat scenario, the maximum inundation zone crosses the Seward Highway and the Seward Lagoon.

A new study, "Changes in population evacuation potential for tsunami hazards in Seward, Alaska, since the 1964 Good Friday earthquake," published in October 2013, presents sobering information. The study looks at post-disaster redevelopment within the Seward inundation areas, and uses pedestrian evacuation modeling for tsunami hazards. It examines how quickly people in Seward's inundation areas would have to leave in order to survive local tidal waves, both under today's physical landscape and how they did during the 1964 landscape.

The study suggests that evacuation travel times have increased in modern-day Seward due to the relocation and expansion of the port and harbor facilities, and that Seward's population vulnerability to tsunamis also has grown since '64. Also, that the majority of individuals threatened by tsunamis today in Seward are employees, customers and tourist populations, rather than residents in their own homes.

Travel times in areas where Seward deaths likely occurred in '64 are estimated to be between 2-4 minutes, and up to 5-9 minutes for those who were on the docks or breakwaters of the Small Boat Harbor on the northeastern shore of the community, Wood said. Modeled evacuation times based on the current landscape suggest that most residents in the maximum tsunami hazard zone would require less than two minutes to reach safety. In winter conditions, when the presence of snow may constrain evacuations to the roads, the evacuation time would be even longer.

"If there's any amazing story, it's that the 9.2 quake in 1964 killed only 130 people," said Michael West, director of the Alaska Earthquake Center. "I don't mean in any way to show disrespect for those who perished in Seward, but the most similar earthquake to '64 is the 2004 Sumatra earthquake, 40 years later. The magnitudes were about same, it occurred in a similar environment, and killed 2,000 times as a many people as '64. That's just inconceivable." Another example, is the magnitude 6.3 earthquake in Christchurch, New Zealand in late 2011 that killed 185 people, and, which has a similar geology and liquefaction hazard as many areas of Alaska, West said. "We could have a 6.5 earthquake (in Seward) tomorrow that would be more devastating than what happened in 1964. It doesn't take a magnitude 9 earthquake to trigger one of the submarine landslides in Seward. It could happen spontaneously. You might not even feel it."

 

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