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Miami part of EarthScope: Continental scale seismic observatory
Miami University has joined the continent-wide EarthScope project with the recent installation of an EarthScope Transportable Array seismic station at its Ecology Research Center.
EarthScope is a National Science Foundation program to study the structure and evolution of the North American continent by installing hundreds of ultra-sensitive seismometers, GPS stations and other scientific instruments across the United States.
EarthScope also will help locate and define previously unknown earthquake-prone faults deep beneath Ohio, according to Michael Brudzinski, associate professor of geology and environmental earth science. Brudzinski has been involved with EarthScope since it began in 2004 (see sidebar).
The Transportable Array (USArray), one component of EarthScope, is a network of 400 high-quality broadband seismographs that are being placed in temporary sites across the contiguous United States from west to east, and then to Alaska, in a regular grid pattern. After a residence time of two years, each instrument is picked up and “leap frogs” to the next location on the eastern edge of the array.
When completed, nearly 2,000 locations will have been occupied during the 10-year program. The first footprint was established from north to south along the westernmost quarter of the U. S. in 2004.
To see a map of network stations across the country, click here.
Miami’s Transportable Array Seismic Station
Brudzinski organized the efforts to identify where the grid of seismometers will be placed in Ohio. The installation at the Ecology Research Center (ERC) on June 29 of Transportable Array station P49A was one of the first in the state. All seismic stations in Ohio are planned to be installed before winter.
The EarthScope seismic station “will be a great educational resource for students here at Miami,” Brudzinski said. “Since I have had several active field experiments where students are involved in the deployment and servicing of seismometers in various parts of the world, it is a great help to have a real seismic station deployed in our backyard.”
How does a Transportable Array seismic station work?
To see a slideshow of different Transportable Array stations around the country, click here.
A Transportable Array seismic station consists of a seismometer — which detects and measures Earth’s ground motion — a data acquisition system and communication equipment. They are buried in a sealed, thermally insulated chamber, or vault, about six feet below the surface. The seismic station also includes a solar panel to power the batteries and a freestanding communications module to transmit real-time data via satellite, phone or Internet.
The seismic stations are laid out in a grid pattern roughly 44 miles (70 kilometers) apart in locations that are as free from outside vibrations as possible.
The buried seismometer is the key instrument at a seismic station, according to EarthScope. The seismometer's sensors are extremely sensitive and can pick up a broad spectrum of motions ranging from low-amplitude background vibrations — such as those generated by wind, water or traffic — to signals from local, regional and distant earthquakes.
The lower the background noise from human and natural sources such as traffic and swaying trees, the more likely the station will be able to detect faint earthquake signals. Miami’s ERC provides a quiet home for the instrument.
EarthScope’s seismometers are so sensitive that they can detect shockwaves from the smallest quakes in the United States and from magnitude-5 earthquakes anywhere on Earth.
They will also help locate previously unknown faults in Ohio like the one that resulted in a swarm of earthquakes near Youngstown last year, Brudzinski said.
Click for part two.