This summer is going to be busy in upper Prince William Sound. Not just for fishing, shrimping, kayaking and other recreational boating. But for scientists to continue research and modeling on a massive landslide threatening to crash into Barry Arm, and send a potentially devastating tsunami around the corner to Whittier.
Barry Arm, northeast of Whittier, is home to Barry, Cox and Cascade glaciers. They’ve been retreating at a rapidly increasing rate, especially over the last 10 years, leaving a very large mass of very steep, very unstable material on the northwest side of the fjord. At current estimates, if that mass comes down at once, the resulting tsunami wave could be 30 feet tall when it hits Whittier.
Scientists have been working to survey and monitor the area, in an effort to better understand the tsunami risk and increase the amount of warning time that could be provided to communities and boaters in the sound. That work continues this spring and summer.
One of those projects will be conducted by Coast Survey, a division of the National Oceanic and Atmospheric Association.
“And they’re the folks out there in the big white boats that you’ll see again this summer in Prince William Sound that are taking new bathymetry surveys and going up and down the coastline and all around. And what they’re doing is finding the shape of the land underneath the water. That is a huge part in determining how any tsunami wave is going to move through Prince William Sound. It helps us determine the speed and the volume of water that’s available for a wave to occur,” said Dave Snider, Tsunami Warning Coordinator with NOAA.
Seismometers and satellite imagery will help keep an eye on how much and how fast the slope might be moving, and how much factors like heavy rains, freeze and thaw temperatures or small earthquakes might impact the slide mass. The data is creating a baseline of what could be considered normal activity in Barry Arm to better identify signals of unusual activity that could mean a slide is imminent. Snider says the Tsunami Warning Center is hopeful this data will allow them to provide advanced warning.
“My ideal would be days or weeks," Snider said. "We’re nowhere close to that and the way that we’re going to get there is through additional meteorological monitoring on top of the satellite overpasses and the groundwork that we’re doing to understand what the land is doing but being able to determine what is the triggering factor here and what is making the ground move a little bit more than usual or a lot more than usual.”
If a massive slide occurs, even immediate notification would probably be too little, too late for boaters or campers who happen to be in the immediate vicinity of Barry Arm. And it wouldn’t do much to help Whittier, either.
“The problem right now is the math tells us that if a significant landslide occurred, that the travel time from Barry Arm to Whitter is about on the order of 20 minutes. And anybody that’s got a handful of kids and home and a dog to grab and put in the car knows that moving quickly anywhere in 20 minutes is very difficult,” Snider said.
For more information, the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys, maintains a webpage on the Barry Arm landslide risk, with information gathered to date, current study work and updates on slide mass movement.