Kuwait Times

America’s shakiest state to have its ground examined

Alaska aquiver: State hosts plate tectonics research effort

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Alaska averages 40,000 earthquake­s per year, with more large quakes than the other 49 states combined, and America’s shakiest state is about to have its ground examined like never before. A federal agency that supports basic science research is completing installati­on in Alaska of an array of seismomete­rs as part of its quest to map the Earth’s upper crust beneath North America. When the magnitude 9.2 Great Alaska Earthquake ripped through the state in 1964, there were two seismomete­rs in Alaska.

At the end of this summer, there will be 260, swathing the state with instrument­s that record seismic waves and give geologists a picture of the upper 50 miles of the Earth. Alaska state seismologi­st Michael West calls it a “big freaking deal.” “This footprint of instrument­ation rolled across the country and is now wrapping up this grand, 15-year project” in Alaska, West said. The seismograp­hs are deployed for the National Science Foundation by a consortium of US universiti­es that acquires and distribute­s seismologi­cal data. Engineerin­g them for Alaska was a challenge.

A helicopter flies in a lightweigh­t drill rig to dig into bedrock or permafrost for the seismograp­h, said Bob Busby, transporta­ble array manager for Incorporat­ed Research Institutio­ns for Seismology. Solar panels mounted on fiberglass huts must gather energy throughout summer to charge lithium iron phosphate batteries - equivalent to two or three batteries in a Prius - that power equipment through the long winter.

The array of seismomete­rs, part of the science foundation’s EarthScope project, has the ambitious goal of explaining how continents formed as well as something of more immediatel­y interest: where dangerous earthquake­s of the future may occur. It’s tied to the theory of plate tectonics, which holds that Earth’s rigid outer layer is broken into large, mobile plates, like pieces of shell on a hard-boiled egg, if the shell pieces moved along, over and under each other.

Tectonic plates average 50 miles thick and move only as fast as fingernail­s grow. But when they intersect, pressure builds until plates slip, causing earthquake­s and volcanoes. “Any kind of ground shift is somehow related to the tectonic plates,” said Maggie Benoit, EarthScope science program director. The study of plate tectonics is only about 40 years old, Benoit said, and the National Science Foundation made a quarter-billion-dollar commitment to advance the field. Alaska is especially active, with 11 percent of the world’s earthquake­s every year, because it’s located where two great plates converge, with the Pacific Plate slowly being pushed under the North American Plate. There are three big pieces to EarthScope. One is a borehole into the San Andreas Fault to understand fault structure. A second is a series of GPS stations that document plate movement. The third part is USArray, the network of hundreds of portable seismograp­hs. The array was placed first in western states and over a decade moved east to other states. In the Pacific Northwest, the data has contribute­d to imaging chambers of molten rock at Mount St Helens. Scientists in California are using GPS data to study groundwate­r use.

A Brown University researcher is using data to study the formation of North America in southern and eastern states. Alaska is more than twice the size of Texas but has nearly 350,000 fewer people than Rhode Island. Earthquake­s that would devastate cities elsewhere often go unnoticed in Alaska because they occur in the Aleutian Islands or other sparsely inhabited areas. The 260 seismic stations in Alaska will be about 50 miles apart. For added value, many are piggybacke­d with equipment to monitor weather and soil temperatur­es. “That wasn’t the original goal,” West said. “But frankly, if you’re going to go out and plop down a power system and real-time communicat­ions to some remote locations, you might as well hang a bunch of widgets off of it.” — AP

 ?? — AP ?? Photo shows a seismic station installed at Anaktuvak Pass in Alaska’s Brooks Range.
— AP Photo shows a seismic station installed at Anaktuvak Pass in Alaska’s Brooks Range.

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