OREGON STATE UNIVERSITY

Oregon Coastal Airports Vulnerable After Major Earthquake, Tsunami, Scientist Says

06/12/2006

CORVALLIS, Ore. – Emergency planners counting on the availability of Oregon's coastal airports to stage rescues and bring supplies following a major earthquake and tsunami nearby in the Pacific Ocean may want to think twice about such plans.

Many of Oregon's coastal airports would be out of commission because of earthquake damage, tsunami inundation and debris, or lack of instrumentation for approaches, according to a survey done by Oregon State University earthquake researcher Chris Goldfinger.

"Most of the airports are at low elevation and have relatively short runways, which could make it difficult for fixed-wing aircraft to land in the aftermath of a major earthquake because of water and debris," said Goldfinger, an associate professor of marine geology in OSU's College of Oceanic and Atmospheric Sciences. "Lack of instrument approaches and working navigation aids may also hinder the use of helicopters if the earthquake happens during bad weather.

"The good news is that there are some concrete things that can be done to make many of these towns more accessible, such as setting up Global Positioning System (GPS)-based instrument approaches that would make it easier for helicopters to land without needing ground aids," he added. "The procedures could also allow helicopters to use local sports fields as well as airports and no new hardware is required."

Goldfinger is one of the world's foremost experts on the Cascadia Subduction Zone, the offshore area in which Juan de Fuca tectonic plate is subducting beneath the North American plate, creating a region that is particularly susceptible to a major earthquake. Goldfinger's research, which includes analysis of sediment deposits, suggests that there have been 23 large earthquakes off the Pacific Northwest coast during the past 10,000 years. At least 16, and possibly 17, of those events have been full ruptures of the fault zone, requiring an earthquake of magnitude 8.5 or better.

Such an earthquake likely would uproot highways, destroy bridges and render much of Oregon's Highway 101 unusable for days, or even weeks at a time. Goldfinger's informal survey of coastal airports suggests that they may not be much help, either.

"One of the issues is vulnerable hangars used by the Coast Guard," said Goldfinger, who is a pilot. "None are earthquake-resistant and in a major earthquake they likely would completely collapse, rendering much of the rescue capability useless before the first wave ever comes ashore."

"As one Coast Guard official told me, 'We'll be victims or survivors like everybody else.'"

On the positive side, the airport in Newport stands out as one that may experience some earthquake damage, but its combination of a long runway, elevation of 130 feet and good instrumentation could keep it from shutting down completely.

"Preparing for an earthquake and possible tsunami is something that Oregon is coming to grips with, yet it isn't something that can be done overnight," Goldfinger said. "Much of the early effort has gone into warning systems and evacuation routes; thinking about emergency rescue scenarios and supply transport is another step in the process."

Goldfinger based his assessment of the airports on their runways, elevation, instrumentation, proximity to the ocean and underlying geology. That assessment is as follows:

Astoria: Earthquake damage is likely for the Astoria airport. The runways, which are 10-15 feet in elevation, likely would be littered with debris from an earthquake and tsunami, but could be cleared. Instrument approaches include GPS and ILS.

Bandon: Earthquake damage is possible, but tsunami damage unlikely because of a runway elevation of 123 feet. Bandon's longest runway is 3,600 feet; it has no instrument approaches.

Brookings: Earthquake damage is possible, but no tsunami damage because of a runway elevation of 459 feet. Brookings' longest runway is 2,900 feet; it has no instrument approaches.

Cape Blanco (Denmark): Earthquake damage is possible, but no tsunami damage because of a runway elevation of 214 feet. Cape Blanco's longest runway is 5,100 feet; it has no instrument approaches.

Florence: Earthquake damage is possible and debris could be a problem from a tsunami. Florence's runway elevation is 51 feet, with the longest runway 3,000 feet. There are no instrument approaches.

Gold Beach: Earthquake damage is probable, as is tsunami debris. The runway elevation is 18 feet, with the longest runway at 3,200 feet. There are no instrument approaches.

Newport: Earthquake damage is probable, though tsunami damage isn't an issue because of the 130-foot runway elevation. The longest runway is 5,398 feet, and Newport has ILS, VOR and GPS instrument approaches.

North Bend: Earthquake damage is probable and tsunami damage is likely due to a low runway elevation of just 13 feet. The longest runway is 5,321 feet, and North Bend has ILS, VOR and NDB instrument approaches.

Pacific City: The airport faces probable earthquake damage and almost certain inundation from a moderate-sized tsunami because of its runway elevation of just 5 feet. The longest runway is 1,875 feet; there are no instrument approaches.

Seaside: The airport faces probable earthquake damage, and certain inundation and debris from a moderate-sized tsunami because of a runway elevation of just 6 feet. The longest runway is 2,360 feet; there are no instrument approaches.

Siletz Bay: Earthquake damage is possible, as is debris from a tsunami during an especially large tsunami. The runway elevation is 69 feet, the longest runway is 3,400 feet. There are no instrument approaches.

Tillamook: Earthquake damage is likely. A tsunami would bring probable debris and partial inundation. The runway elevation is 17 feet, with the longest runway at 4,990 feet. Tillamook does have a GPS instrument approach.

Toledo: Earthquake damage is likely, and in a tsunami, probable inundation and debris would take place. Despite being located well inland, the 7-foot elevation and location adjacent to Yaquina Bay make it vulnerable. The longest runway is 1,750 feet; there are no instrument approaches.

Waldport: Earthquake damage is likely and tsunami debris possible. The runway elevation is 41 feet, with the longest runway at 2,000 feet. There are no instrument approaches.