New instruments monitor what’s shaking beneath West Virginia
Last August, only one seismic monitoring station could be found in all of West Virginia — at the state’s Geologic and Economic Survey headquarters at Mont Chateau, in Monongalia County, just south of the Pennsylvania border. In the past year, 14 more seismic stations have been installed across the state and are generating a steady stream of data about what’s shaking in, or more accurately, under, the Mountain State.
The new seismic monitoring equipment was placed along a grid, with stations located 70 kilometers (about 45 miles) apart across the state, as part of the National Science Foundation-funded Transportable Array experiment. The experiment began 10 years ago in Washington, Oregon and California, where 400 seismic monitors were installed at sites 70 kilometers apart, and left in place to produce steady streams of data for two years. After two years, the monitors were dug up, trucked eastward and re-buried for another two years at new sites 70 kilometers away, before the process was repeated, allowing the experiment to leapfrog across the country.
The first of the Transportable Array monitors reached the Atlantic Coast late last summer, allowing seismic stations along the western edge of the experiment to be diverted to Alaska, where they will be installed in 85 kilometer grids in two-year intervals and, eventually, march their way across that earthquake-prone state.
While most of the seismic stations installed in West Virginia will be dug up and recycled for use elsewhere when their two years here are up, it now appears that National Science Foundation funding is available “to leave six of the stations behind for an additional two years, and then, contingent on funding, to leave three or four of those stations permanently installed,” according to Ron McDowell of the West Virginia Geologic and Economic Survey.
Because of temperature and pressure issues, scientists can’t drill deep under the earth’s crust to see what’s inside. So they measure vibrations on the earth’s surface as a way to observe interior features, similar to how doctors use X-rays to create images of the inside of the human body. By observing energy that’s released and ripples outward from earthquakes, and measuring the time it takes seismic waves to reach seismometers, scientists can determine what lies beneath the planet’s surface. By mapping changes in the size of seismic waves as they travel through the earth, seismologists also can determine what structures, rock types and temperatures exist beneath the surface.
Having a large array of seismometers recording data “helps bring things into focus” when a seismic event occurs, said Michael Hohn, director of the Geologic and Economic Survey. “It helps determine things like the depth of an earthquake, which can be important in determining whether an earthquake could have been induced by human activity. The more seismic monitors you have operating in an area, the sharper the picture you’ll have of what’s happening beneath the surface. It’s a matter of triangulation.”
The EarthScope seismic stations used in the Transportable Array program are buried 6 feet below the surface inside 3 1/2-foot-wide waterproof tanks. Power is supplied by solar panels mounted on posts about 20 feet from the tanks, and data is transported to a processing center by either cellular, broadband or satellite communications systems.
EarthScope earthquake monitoring stations are built, operated and maintained by the Incorporated Research Institutions for Seismology, with funds from the NSF. Data produced by the array are available immediately, free of charge, to anyone.
“We’ve learned a lot more about earth the last 10 years than the previous 30 to 40 years,” wrote geophysicist Jean-Bernard Minster, of the Scripps Institution of Oceanography, in a 2013 article in the journal Science. “The amount of very high quality data and science generated by EarthScope is spectacular.”
“It’s almost like using radar to locate deep structures,”said Hohn. “It’s producing information that will be useful both for academicians and for those interested in developing natural resources. We all want to know what’s happening down there.”
Contact Rick Steelhammer at email@example.com or 304-348-5169.