Earth-Observing Project a Big Deal for Alaska

Alaska sits on the collision point of two of Earth’s colossal plates, which makes the state North America’s leader in earthquakes and volcanic eruptions. This unstable perch has also made Alaska part of a huge national study that local scientists are calling “a dream come true.”

Starting in summer 2004, scientists and engineers will travel all over Alaska to install 151 new GPS receivers and other instruments that will be part of a nationwide effort to find out more about the moving crust under our feet. The National Science Foundation has devoted $219 million to the Earthscope project, which includes the installation of GPS receivers and the deployment of roving seismometers throughout the U.S., the use of radar aboard satellites to measure changes in Earth’s crust, and the drilling of a 2.4-mile borehole into the San Andreas fault.

Alaska earth scientists are excited at the potential of a statewide network of sensitive GPS receivers, which allow them to measure the speed of Earth’s plates—moving about as fast as fingernails grow—and the bulging and shrinking of volcanic mountains.

“It should be quite a revolution,” said Jeff Freymueller, a Geophysical Institute associate professor of geophysics who has used GPS receivers to find that parts of the Kenai Peninsula have risen three feet since 1964 and also to measure the inflation of Okmok volcano in the Aleutians. “We’ll go from having less than 10 of these high-quality GPS sites to having 200 of them in a few years.”

The dense network of receivers that scientists call the “Plate Boundary Observatory” will enable them to detect subtle ground motions that reveal weak points in Earth’s crust known as faults. Slippage along the Denali fault caused the largest earthquake recorded on the planet in 2002, a magnitude 7.9. The receivers will also allow scientists at the Alaska Volcano Observatory to detect bulges in volcanoes, possibly helping them predict eruptions.

“We’re hoping to learn how magma (molten rock) accumulates, and how volcanoes respond to the seismic waves of a big earthquake,” said John Power of the Alaska Volcano Observatory in Anchorage. “(The new network) is a great thing for us.”

During the coming years of the experiment, the National Science Foundation’s investment in Alaska will pay off with an eruption or two, Power said.

“When you look at the entire North American and Pacific plate boundary, from Mexico to Attu Island, Alaska is the only place certain to have an eruption within the 10-year life of the study.”

Pavlof volcano is the most active volcano in North America (Hawaii is more active, but not considered part of the continent). Akutan volcano is second, and Shishaldin is third. The volcanoes are part of the Aleutian Islands, which will receive about one third of the 151 new GPS stations. Dozens more will be planted in a grid across Alaska, in such far-flung places as St. Matthew island, Rainy Pass Lodge, Arctic Village, and Hydaburg.

Ben Pauk recently took on the responsibility of overseeing the installation of the 151 new GPS stations in Alaska. Formerly with the Alaska Volcano Observatory, Pauk is now the Alaska regional engineer for Unavco, Inc. Unavco will install eight stations in summer 2004, beginning with several along the Denali fault, one in Yakutat, and one in the village of Sand Point.

The Alaska stations will be part of more than 800 GPS stations planned for the west coast and other areas of the continental U.S., with most along the boundary where the Pacific plate meets the North American plate. In addition to the GPS receivers, a traveling band of 400 high-precision seismometers will visit the entire Lower 48 and Alaska in the next 10 years, resulting in what Steve Hickman of the USGS Earthquake Hazards Program in Menlo Park called “an infrasound of the entire continent.”