A freight train passing through Socorro. EMRTC’s 4th of July Fireworks display. Big trucks rumbling through the area.
Those are just samples of what registers on sensitive earthquake instruments at New Mexico Tech.
Tucked away on a hilltop in the backyard of Tech’s campus is the Incorporated Research Institutions for Seismology Portable Array Seismic Studies of the Continental Lithosphere Instrument Center — IRIS/PASSCAL for short — the largest facility of its kind in the world.
And what kind of facility is that?
Director Bruce Beaudoin, who supervises the care and handling of seismographic instrumentation, described IRIS/PASSCAL as doing something akin to “a lending library … for seismographs.”
In other words, the seismographs are checked out, at no cost to the users. The only requirement is the data must be publicly available to other researchers.
It’s the facility that provides instrumentation for the National Science Foundation, Department of Energy, and other funded seismological experiments around the world. From Alaska to Antarctica to the outer reaches of Inner Mongolia, instruments shipped from PASSCAL can be found measuring earthshaking events virtually all over the world.
“We are a National Science Foundation funded facility to support seismic instrumentation, equipment maintenance, software, data archiving, training, logistics, and field installation,” Beaudoin said. “Our mission is to educate incoming students on how to use the equipment, to provide the resource to principle investigators that go out and do seismic research, and to ensure that the equipment works”
Although PASSCAL does not assemble seismometers, its scientists must keep them working perfectly.
“We do quality assurance on it before it goes out to the users,” Beaudoin said. “And then we’re responsible for ensuring the data get into a public archive in Seattle, the sister facility of ours.”
What that means is that any researcher who borrows PASSCAL’s equipment has two years of restricted access to the data, but after two years the waveforms are a public resource.
Waveforms are the printed “wiggles” from a seismograph.
“The instruments we have, they have two components,” he said. “A sensor that measures ground motion and that can be down to the micro-meter.”
Basically it can pick up an earthquake on the other side of the earth.
“The other component is the data logger, which takes the signal coming from the sensor, digitizes it, puts a time stamp on it and stores it,” he said. “That’s what gets archived.”
Instruments that communicate with satellites are sometimes used, especially in Antarctica. “They communicate the state of health of a station, such as battery condition, temperature, and then some data transmission,” Beaudoin said.
These are primarily in Antarctica.
“Because of the remoteness of the stations you have one chance in a year to visit them,” he said. “If they go offline, you want to know, so when you go to visit you’ll know what you have to do to fix it.”
He said their polar teams get support and funding through the Office of Polar Programs.
“The reason we get that funding is because it’s a harsh environment,” Beaudoin said. “Our instruments require power. There’s only six months of sunlight down there. We had to engineer a solution for operating through the months of winter. And it’s extremely cold. The outside temperature is colder than where the instruments can operate, so there has to be special insulation to keep them going.”
The polar seismographs must be able to work at minus-55 degrees.
Instruments from PASSCAL have also been planted in Inner Mongolia, Tibet, Greenland, Alaska, northern reaches of Canada, hard places to get to,” Beaudoin said. “We’ve really worked all over the world. We’ve supported over 1,300 experiments since 1986. They’re essentially everywhere.”
Staff physicist Dave Thomas said the earthquake instruments loaned out by IRIS/PASSCAL are extremely sensitive.
“Some sensors here at PASSCAL are used to constantly measure earthquakes worldwide, and are sensitive enough to record train passages, nearby trucks and cars, and even the 4th of July Fireworks celebration,” he said.
PASSCAL currently maintains four seismometers in its facility that can register earthquakes anywhere in the world.
“The 2016 Alaska earthquake near Anchorage was a 7.1 magnitude, and took eight minutes to be registered on the seismographs here at PASSCAL,” Thomas said. “That was 2,700 miles away.”
That means the shockwave was traveling 20,000 miles an hour, he said. Through the earth.
To illustrate the sensitivity of PASSCAL’s instruments, Thomas said trains passing through also register on the seismographs’ waveforms with a time stamp.