When the magnitude-9.0 earthquake struck off the coast of Japan on March 11, 2011, the results were catastrophic: nearly 16,000 dead, more than 3,000 others missing, and hundreds of billions of dollars in damage.
In the early morning of March 11 in Alaska, concern over the enormous earthquake across the Pacific Ocean spurred alerts of potential tsunami waves in some of Alaska’s coastal communities. The impacts in Alaska were extremely minimal, but for some longtime Alaskans, the devastating Japanese earthquake was a sobering reminder of Alaska’s own seismic past, bringing to mind the 1964 Good Friday earthquake that rocked Southcentral Alaska and became the second-largest earthquake in recorded history.
But one year after the earthquake and the subsequent tsunami that wiped out coastal villages in Japan, what have researchers learned? And what is the likelihood that such a quake could happen again in Alaska?
The great equalizer
Natural disasters are a great equalizer: When a devastating earthquake hits, there’s little difference between the developed and developing world.
Tsunami warnings might be a little better and communication systems might be a little more intact in developed countries, but when it comes to predicting an enormous temblor, most of the world is on equal footing.
That doesn’t mean scientists don’t continue to try to determine methods for predicting mega-earthquakes like the one in Japan. According to Dr. Natalia Ruppert, a seismologist with the Alaska Earthquake Information Center, the Japan quake was unique because Japan -- a developed country with a rollicking seismic past -- is particularly well set up to measure and study earthquakes.
So when the 9.0 quake hit last year, scientists quickly began evaluating the data that preceded the quake -- including cross-referencing seismic data with other information, like possible atmospheric disturbances caused by such a massive geophysical event.
“They always look at that (data), Ruppert said, “and especially in Japan. Japan is so well instrumented -- they also look at observations from satellites, trying to coordinate the seismicity with atmospheric phenomenon like electromagnetic disturbances.”
Some scientists believe that those electromagnetic disturbances, if researchers can come to recognize them in the leadup to a major quake, might eventually become a method of an earthquake early-warning system.
Unfortunately, Ruppert said, she’s not fully convinced that the data gathered so far is conclusive. Indeed, a 2007 report from NASA noted that “Any possible links between the seismo-tectonic processes in the ground and the atmosphere/ionosphere and earthquake precursors still are not well understood by the scientific community.”
For her part, Ruppert said that the data so far isn’t consistent enough.
“If it correlates with three earthquakes but not with three other earthquakes, it’s not really a reliable predictor of earthquakes,” she said.
Still, scientists continue to refine their efforts, and if it eventually proves effective, it could provide a warning of a few hours or more for an area with an impending quake.
Will Alaska see another megaquake?
In the meantime, what does a mega-earthquake like the one in Japan mean for Alaska’s own seismicity? Not much, according to Ruppert. Seismic activity, even strong activity like in the Japan quake, typically doesn’t carry very far unless the material is conducive to it, she said.
The distance that seismic activity can travel depends on the material and the depth and severity of the quake.
“You can feel a magnitude-2 if you’re on top of it,” Ruppert said, “but 10 miles away you wouldn’t feel it.” Earthquakes the strength of the one in Japan can lead to slightly increased seismicity elsewhere in the world, but it typically wouldn’t last more than a few minutes and the quakes themselves are likely small, she said.
Alaska already has tens of thousands of earthquakes every year of varying magnitude. The most recent large quake came in June, when a magnitude-7.3 quake struck near the Fox Islands in the Aleutian chain. Many of Alaska’s strongest quakes in recent years come in remote parts of the Aleutians.
The anniversary of the Japan quake comes in a window of seismic activity around Southcentral Alaska, as two earthquakes earlier this week were felt in the population centers on and around the Kenai Peninsula, including a magnitude 4.1 quake that occurred less than 40 miles from Anchorage.
On Friday, the Alaska Volcano Observatory also raised the alert level for Iliamna volcano, located about 130 miles southwest of Anchorage, after several days of increasing seismic activity.
While predicting when or where a major quake might strike Alaska next isn’t a feasible task, Ruppert had a couple of educated guesses for where Alaska’s next big quake might come from.
The plate boundary below Kodiak Island hasn’t experienced a large earthquake since the 1800s, so that one may be overdue, Ruppert said. She also said that the Castle Mountain fault north of Anchorage is capable of producing a magnitude-7 or greater quake every few decades, and that could be enough to impact a community, Ruppert said. Anchorage and Southcentral Alaska are very different places than when the 9.2 quake struck in 1964, and the human and economic toll could be much greater if or when another devastating temblor comes along.
“In Anchorage, it’s so densely populated, and it doesn’t have to be a magnitude-9 to damage (the city),” Ruppert said. “It could be a magnitude-7 and still cause damage.”
Contact Ben Anderson at ben(at)alaskadispatch.com