EARTHSCOPE

Ambitious Program Takes Geologic Pulse Of Northwest, North America

By Ben Raker

EarthScope, the largest continental geology project ever funded by the National Science Foundation, is ramping up operations this year, installing a vast network of surface and subsurface instruments and establishing outreach programs to involve the public in findings about the structure and movements of the North American continent.

The program's efforts are already underway in the Northwest, including at Mount St. Helens, and activities will continue to expand over the next 4-5 years.

Launched in September 2003, EarthScope is funded with approximately $200 million over its first five years to construct facilities and an instrumentation network that will go on exploring the earth many years after that.

"It's something we don't always appreciate but North America in general and the United States in specific is the perfect natural laboratory for a project or a grand undertaking such as EarthScope,” says director Gregory van der Vink, who is based at the national headquarters in Washington, D.C.

One such site is Mount St. Helens, where EarthScope equipment was recently installed. NWS&T recently accompanied a field expedition to the volcano to see firsthand some of the EarthScope instrumentation being deployed (see sidebar).

EarthScope will use a multidisciplinary approach to address fundamental questions such as how continents form, how movement takes shape along faults, and how volcanoes behave. The program will try to tie movement above ground with data about strain near the surface and seismic imaging at depth. It will also involve a deep borehole station being drilled nearly two miles into California's San Andreas Fault. Data acquired from the array of stations will be available online for use by researchers and educators or anyone else with an interest.

The EarthScope project will involve three main components: the Plate Boundary Observatory PBO, which does the geodetic work, GPS and strainmeters; the USArray, which handles the seismometer network; and SAFOD, which is involved with site-specific deep drilling at the San Andreas Fault.

"The promise of EarthScope," says van der Vink, "is to relate what we think we see in the interior of the earth to what we're measuring on the earth's surface." He says that various tools and disciplines have been advancing rapidly in recent years, enabling a unifying project of this sort. "With EarthScope, we're really trying to put the puzzle together."

Within the natural laboratory North America provides, van der Vink says the Northwest is one of the most exciting regions because of its active geology and range of tectonic regimes. He cites the subduction zone of the coast, volcanism at Mount St. Helens, and the mantle plume at Yellowstone National Park as a few highlights.

"The Northwest United States basically has it all," he says. But he also jokes that the East Coast's older, more-established geology might just be more sophisticated: "On the East Coast, we like our geology a little older–not like all that nouveau tectonics out there. It's a little ostentatious and showy."

Nouveau tectonics aside, there are a lot of EarthScope projects in the works for the Northwest.

First, there is the work being done on near-surface phenomena. The branch of EarthScope that handles this is the Plate Boundary Observatory, operated by UNAVCO and based in Boulder, Colo. UNAVCO is a non-profit, membership-governed organization that supports research applications of high-precision geodetic and strain techniques such as the Global Positioning System (GPS). Plans call for the installation of 875 GPS stations and 175 strainmeters across the American West.

EarthScope's first GPS station was established in Alaska's Aleutian Islands in May 2004 to monitor volcanic and tectonic activity in the area. Others are up and running at sites in Oregon and Washington.

Over the next few years, 149 GPS stations and 8 strainmeters will be installed in Oregon, Idaho, and Washington alone.

"There are some areas where we're filling in gaps where there hasn't been any instrumentation," says Katrin Hafner, head of the regional office in Ellensburg, Wash. She mentions southwest Oregon as an area of interest because of the transition there from strike-slip motion typical farther south to the subduction zone farther north.

The first strainmeter in the Northwest is to be installed in February 2005 near Port Angeles, Wash., to monitor the northward movement of the coastal area. Others will be installed to help understand a phenomenon called "slow earthquakes." Slow earthquakes are a recently observed phenomenon where pressure is built up and then released over time without a big seismic event.

Meanwhile, another program called USArray is installing a grid of seismometers across the West–the seismic component of EarthScope. Fully installed, there will be 400 stations within the USArray.

It's hoped this program will form a three-dimensional image of the crustal structure and the mantle structure of the North American plate, says Robert Busby, a chief of operations at USArray.

Whenever an earthquake occurs–even far across the globe–the seismometers register data about the ground that seismic waves passed through. They continuously transmit their data to a central processing center. By setting up a grid of stations, the array will piece together a map of the subsurface in the American West. Eventually the westernmost part of the array will be picked up and moved east. The network will gradually roll over the entire U.S., so that each region has had a few years of readings taken. "It's sort of like doing a CAT scan on the entire continent," says Busby.

About 70 seismometers have already been installed in California. The first stations were installed in Washington state in September 2004, and more will be installed in Oregon and Washington in 2005.

One of the Washington seismographs was sited at the Wishkah Valley School, a small K-12 facility about 12 miles north of the town of Aberdeen. Although the educational programs to go along with the station are still being worked out, it has already been of great interest to the students.

"They know they're not big-city kids and this makes them feel real important," says Don Hay, the school's science teacher. "It takes real-life problems in science and brings it into the classroom so that science isn't just something you learn from a book or see on TV–it isn't something that's far away, it's something that's real, done by real people, to solve real problems."

Educational outreach will be a major priority as EarthScope moves forward. It's also one of director van der Vink's favorite things to discuss.

"We see this very much as a grassroots project," he says. "Schools and museums or people who are interested who would be willing to host a station and participate in this experiment–we're excited to have them do it."

For more information about EarthScope and their outreach programs, visit www.earthscope.org or email earthscope-info@earthscope.org

Ben Raker is a freelance writer and editor who has studied science writing at the University of Washington.

Top: An EarthScope GIS installation on Mount St. Helens. Photo: Ben Raker

A map of the U.S. showing planned EarthScope stations. Photo: EarthScope

Bottom: Robert Busby (right) installs a solar panel to power an EarthScope seismometer near Wishkah Valley School. Photo: EarthScope