by Thomas Guengerich
SOCORRO, N.M., July 14, 2008 – The world’s leading seismology research support center is constructing an innovative instrument test facility at New Mexico Tech.
The university in Socorro is home to the national seismology instrument center, with more than $20 million of top-of-the-line “broadband” seismic sensors and another $50 million of other seismic equipment, all funded by the National Science Foundation. The state-supported research university now is developing new capabilities for testing, calibrating and maintaining those instruments.
Since 1998, the Socorro research university has been home to the Program for Array Seismic Studies of the Continental Lithosphere, commonly known as PASSCAL, which conducts over 50 national and global research projects each year and operates a lending library of nearly 8,500 research seismographs. PASSCAL is a division of the Incorporated Research Institutions for Seismology [IRIS], which is headquartered in Washington, D.C.
“We are the international standard for portable seismic research instruments,” said Dr. Rick Aster, the principal investigator for IRIS/PASSCAL at New Mexico Tech and chair of the Department of Earth and Environmental Sciences. “Other nations, like China, are trying to catch up, but we manage, by far, the world’s largest pool of this type of state-of-the-art research instrument.”
“In any year, these instruments might be deployed to South America or Antarctica or anywhere else where there is interesting science to be done,” he said. “Once they come back to Socorro, the PASSCAL staff has to turn them around and redeploy them in new experiments. To do this, we need to expand our low-vibration facilities to help us retest instruments as they come out of the field.”
Right: Dr. Shane Ingate, staff scientist and chief of instrumentation at IRIS-PASSCAL, explains the methodology used in the test vault.
Dr. Shane Ingate and university staff architect Dan Jones designed an innovative small building specifically to test the center’s 1,200 state-of-the-art broadband seismic sensors. The new building will be insulated from cultural noises like vehicles, human footsteps and – thanks to its complete dependence on solar power – even from the hum of standard electrical devices.
“These broadband sensors are so sensitive that they can detect cold air falling from an air conditioning system,” Ingate said. “The cold air is like a waterfall onto the pier. That gentle patter of cold air is masking the background seismic noise that we’re trying to detect while testing and calibrating these seismometers.”
Ingate designed a building that is well-coupled to the ground so seismometers can record natural Earth movements and that will maintain a stable internal temperature.
To achieve that, Ingate designed an innovative test room – or vault – that is separate from the main building. He and Jones devised a construction that includes two 10-foot deep concrete piers inside a non-magnetic room with 2-foot thick pumice-crete walls. Pumice-crete is a lightweight rock material that provides a high thermal insulation value, and is mined in the nearby Jemez Mountains. Atop each concrete pier is a 6,500-pound slab of granite, which will serve as the surface for testing the instruments.
Left: Two broad-band seismometers sit on the test pad at IRIS-PASSCAL. The granite slab was recently added to provide a 'quieter' environment in which to test the seismometers.
The 10-foot deep concrete piers are designed to couple the granite slabs to the ground, so that the granite moves exactly the same as the Earth. The piers weigh over 60 tons.
“Most of our sensors can be tested on a concrete floor in the warehouse,” Ingate said. “But these broadband sensors are the Cadillacs of seismometers. They need to be tested in a specialized vault.”
The PASSCAL facility in Socorro serves as an international lending library, providing the seismological community with state-of-the-art, portable seismic instruments through support from the National Science Foundation.
“IRIS has really democratized seismology,” Aster said. “Now every university doesn’t have to put together its own lab. The instruments are available on loan and all the data is ultimately available to all researchers through the internet.”
Seismologists and other geo-scientists use PASSCAL’s instruments for a wide variety of Earth science research – from the esoteric disciplines, like mapping the Earth’s core, to the societally important studies such as studying hazardous earthquake zones and listening for signs of nuclear bomb tests or other human-caused signals.
In past years, the PASSCAL instrument center would sometimes have to allow sensors to go from one experiment to another without returning to Tech. As the failure rate increased, IRIS PASSCAL program manager Dr. Jim Fowler set a policy that all sensors must be tested every two years.
The broadband systems, which cost about $26,000 each, are returned to Socorro for testing after every deployment.
“No researcher wants a dead or poorly performing instrument,” Ingate said.
The IRIS-PASSCAL center at New Mexico Tech opened in September 1998, as a result of a competitive bidding process. The National Science Foundation previously had supported two instrument centers – one at Stanford University in California and one at Columbia University in New York. The federally-funded Foundation decided to combine the two centers and solicited bids. In the process David beat two Goliaths.
“That was huge for New Mexico Tech,” said Vice President of Research and Economic Development, Dr. Van Romero. “Winning that bid was a huge coup. This is a real jewel and it’s been extremely successful.”
The facility now has 35 full-time employees and more than 20,000 square feet under roof.
New Mexico Tech is a small university that thinks globally. The university is partners with the University of Cambridge in the $75 million Magdalena Ridge Observatory. The university operates an international graduate program for law enforcement officials. University professors, researchers and students are at the vanguard of science and technology in every department.
“Our goal at New Mexico Tech is to provide the infrastructure that allows our faculty and researchers to compete on a national and global basis,” Romero said. “IRIS/PASSCAL exemplifies that strategy.”
Founded in 1984, IRIS is a consortium, with more than 100 U.S. university members, and promotes the collection and use of seismic data with the caveat that all data collected enters the public domain.
“Seismology is a global science – where all the data ends up in a central repository in a common format,” Ingate said. “And it’s available to anyone with a computer.”
Aster has found that data gathered by one researcher often is later interpreted by another researcher to deduce a complete new set of results.
“It’s increasingly common that people retrieve data and do completely new studies from what the original researcher intended,” Aster said.
As one example, after the devastating Sumatra earthquake of December 2004, Aster used PASSCAL data to map the seismic waves that circled the globe, which helped scientists around the world understand the dynamics of that devastating earthquake.
“Seismology is a young science,” Aster said. “We’re still doing very basic science and exploration, and we are really just starting to understand the detailed inner workings of our planet.”
– NMT –