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  Geotimes - July 2008 - Geologic Column

Whole Lot of Shaking Going On
Lisa A. Rossbacher

If you use a MacBook or a MacBook Pro, you are only a few mouse clicks away from having your own seismic station.

New Mac laptops come equipped with Sudden Motion Sensors (SMS), which are designed to detect sudden acceleration (as in, being dropped). When the sensors pick up such a sudden movement, they disengage the drive heads to try to prevent damage (and resulting loss of data) on impact. And now, Daniel Griscom of Suitable Systems, in Wakefield, Mass., has produced a piece of software, called SeisMac, that can turn a personal computer into a personal seismic station.

When Griscom got a new Mac a couple years ago, he began experimenting with the SMS capability (no, he didn’t repeatedly drop it). He thought about creative ways to use the hundreds of data points that could be generated each second, and concluded that a moving graph would be the ideal display. And the laptop seismograph was born.

He initially planned to use the software as a “calling card” to illustrate his programming skills to potential clients. It worked. The Incorporated Research Institutions for Seismology (IRIS) contacted Griscom. IRIS is a group of more than 100 universities that collaborate on research, education and outreach on Earth’s interior and seismic data. IRIS asked Griscom if he would be interested in revising his software to focus more on its educational use. Funding from the National Science Foundation helped make this happen. SeisMac 2.0 is the result.

Griscom also created SeisMaCalibrate to increase the accuracy of the laptop as a tool. With this software, a user calibrates the motion sensors by orienting the Mac in three different directions while entering the accelerometer data. (If anyone sees you during this process, they are likely to think you’ve lost your marbles. The eight-step process includes setting the laptop on its side and back to enter the calibration data.) The software also includes the opportunity to automatically report the data to Griscom. (My calibration was the 867th to be submitted.)

The market for this software is larger than Griscom ever imagined. In the first five months after the initial release of SeisMac in July 2006, nearly 30,000 people downloaded it. A thousand more people accessed the companion calibration program, and more than 200 — including seismologists — sent him comments and suggestions for improvement.

In addition to commenting on the programs, people have also shared information about how they have used SeisMac: on airplanes, on ships and even in the midst of earthquakes. However, the most frequent and valuable use is for education.

SeisMac has proven to be a useful teaching tool, in part because it is remarkably simple to use. Many of us remember when seeing a functioning seismograph meant taking a trip to some location that had a sensor installed in the basement of a building. Remember the process of changing the paper on the drum? And the frustration of discovering the seismograph had run out of ink just before that major event that happened over the weekend? This new software brings the seismograph to the desktop, the countertop and the tabletop of a local coffee house.

In late 2006, Griscom suggested that one potential use for laptop seismometers would be to create a distributed network that reports acceleration data to augment existing networks. In mid-2007, Quake-Catcher Network started doing just that. A group of schools in California, including Stanford and the University of California at Riverside, are linking data from computer accelerometers to create such a network.

The goals of this network are both educational and practical. And the speed of data transmission offers some useful applications. Because information sent over a wireless network moves faster than seismic energy travels through Earth, the potential exists for an early warning system. In a situation in which seconds count, such warnings could make a difference.

Another system that is bringing together seismic data from multiple Macs is the Network for Earthquake Engineering Simulation (NEES) Cyberinfrastructure Center at the University of California at San Diego. NEES is dedicated to storing and sharing seismic data. This software is iSeismograph, and it utilizes the built-in iSight camera as a way to record the information.

Some non-Mac laptops also have accelerometers, too, but many of them are not accessible to programmers. But the Quake-Catcher Network Web site promises that software will be available for PCs soon.

With recognition of the value of this type of software — for teaching, research and collaboration — expanding use of laptop accelerometers seems inevitable, including to computing platforms beyond the Mac.

But for now, here’s a possible new take on the classic “Mac-vs-PC” ad:

“Hello. I’m a Mac.”
“And I’m a PC.”
“No, that’s a P wave.”

Rossbacher, a geologist, is president of Southern Polytechnic State University in Marietta, Ga. E-mail:

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