By Constance See

Special to the Sounder

Is the Pacific Northwest at risk of a megaquake, magnitude 9.0 or greater or a devastating tsunami like Japan experienced in 2011? More than 15,000 died, 2,000 are still unaccounted for and thousands more were injured in that event.

Last month author Kathryn Schulz penned a New Yorker article about “The Big One.” Based on recently discovered tree ring research in the Pacific Northwest, and a collection of oral histories, her material focused on the danger of the eerily quiet Cascadia subduction zone, running offshore from Mendocino, Calif., north to Vancouver Island. It last erupted 315 years ago, resulting in a new western U.S. coastline. Schulz went so far as to suggest that when the Cascadia zone does awaken, it will result in huge tsunami waves, and everyone along the Interstate 5 corridor will be “toast.”

Paul Bodin and Bill Steele are seismologists at the Pacific Northwest Seismic Network based at the University of Washington Seismology Lab. Utilizing more than 300 seismic monitors, PNSN keeps a careful eye on their territory, the states of Washington and Oregon, while sharing information with scientists around the globe.

On July 31, Steele was interviewed on NBC Seattle’s “New Day Northwest” program stating a major earthquake and tsunami are coming to the Pacific Northwest. His forecast window ranged from tomorrow to 50 years from now. Steele said within that time period, Washington state has a 15 percent chance of a magnitude 8 or 9. Southern Oregon’s risk he graded higher at 25 percent. On that same show, Steele suggested everyone prepare with storage food, medicine and water for at least two weeks, and at-risk communities should investigate building vertical evacuation towers.

When interviewed by the Islands’ Sounder, Steele’s associate Bodin was less dramatic. He found the New York article to be “overblown” because “most of our populated areas are outside of the rupture zone.”

“Cascadia is like a stuck window,” he said. “You wonder whether it’s painted shut. I keep a close eye on it. Any earthquake out there would really get our attention. We would be doing better if we had more offshore monitoring equipment.”

Last December, Congress approved a $5 million increase in spending to upgrade the Shake Alert System, a prototype alert program using a series of 300 seismic monitors plus the software and hardware needed to process their data. When finished, it’s expected to cost about $30 million and require an additional $16 annually to maintain.

“When this upgrade is complete, we should have information in seconds, not minutes,” Bodin said.

The majority of seismic monitors he watches are on land, but a few are stationed off the coast of Oregon at the Hydrate Ridge, 60 miles away, and at the Axial Seamount Volcano, 300 miles west of Cannon Beach.

Last fall, geologists Bill Chadwick and Scott Nooner announced a pending Axial eruption. When it spewed lava in April, their predictions were confirmed. A boatload of scientists will join them on a close-up visit to the Axial this month.

While geologists are diving underwater looking for forecasting clues, geodesist Dr. Yehuda Bock is focusing on the skies. A tsunami risk assessment specialist and lecturer working for the Scripps Institute of Oceanography in La Jolla, Calif., Bock and his graduate student Diego Melgar took data from the Japan quake combined with G.P.S. information to back-engineer the event. Diego was awarded the Annual Frieman prize honoring excellence in research for his paper.

“Diego replayed it (the Japan quake) as a real-time scenario and was able to use that information to measure the uplift of the seafloor, then to determine how far inland it would hit,” Bock said. “He was quite accurate. I think maybe in 10 years we will have an extensive G.P.S. system. You need to figure out location and magnitude as fast as you can, because the clock is ticking.”

Accessing and correctly processing data fast is key for accurately forecasting a tsnuami’s reach and destruction potential. The Tokohushu Japan quake was initially estimated to be a 7.2, but ended up as a 9.0, about 30 times more intense. The arriving waves were far higher than many vertical evacuation towers could handle.

A more controversial forecasting method potentially providing days or even weeks advance notice for earthquakes and tsunamis focuses on biological anomalies as precursors. Water buffalo, rats, cattle, pigs and crayfish are being watched for signs of “nervousness” in so-called “psychic animal” research abroad.

As for how the tsunami will affect the islands, the county’s  Department of Emergency Management’s online map tool allows islanders to view the tsunami risk following a Cascadia quake. You can see the maps at sjcgis.org/tsunami-inundation/. According to Cowan, director of the DEM, this is the first time that the department has had a data-driven picture of how the tsunami will affect San Juan County. This data has been collected over the span of 10 years. Prior to that, predictions of the tsunami effects were based on speculation or interpretation from work done on either a larger scale or for locations other than the San Juans.

Since the tsunami hit Japan in March 2011, Cowan said there has been a lot of confusion in the community about tsunami risks.

“The very idea of them can understandably bring up strong emotions, likely due to the extremely vivid images we’ve seen from Japan and the Indian Ocean,” he said.

Some of the most common misunderstandings Cowan hears from the public is that what happened in Japan would be replicated here, and that if you know it’s coming you should get in a boat and ride it out.

Apparently jumping in your boat has worked in outer coast areas where deep open water is close at hand, but will not work here because of the complexity of island waters, which create an unpredictable environment and current speeds approaching 15 knots or more.

Another myth is that a tsunami would only impact the west side of San Juan or Lopez. According to recent data, Crescent Beach and Lopez would be most impacted by a tsunami with flow depths up to 18 feet. Cowan wants people to understand that the tsunami is not so much a wave but more like an extremely fast-moving tidal cycle.

“We want this to be a tool that educates islanders about the risk and teaches them that in the event of a big quake, people near the water should calmly collect their family and things and head for high ground, say 35 feet or more above the water,” Cowan said. “In the islands, high ground is never too far away.”

The vast majority of the islands will not be inundated by tsunami water. According to Cowan, islanders should be aware that the first surge is often not the biggest. Tsunami impacts can continue for 12 hours or more after the first effects.