Professor Laura Guertin's teaching came to life on Tuesday, August 23, as a 5.8 earthquake literally rocked Penn State Brandywine. As associate professor of Earth sciences, she helped install an earthquake monitoring station on campus in 2008 that not only picked up the vibrations from this earthquake, but continues to detect those occurring in South America and even the magnitude 9.0 that devastated Japan in March.
The seismograph, an instrument buried six feet under the campus grounds that measures seismic waves triggered by earthquakes, volcanoes and other sources, is a "significant tool that helps us in Pennsylvania give insight on what's going on across the globe," Guertin explained.
Desks vibrated, computers rocked and Guertin fled her office for the safety of the campus grounds. Immediately, she said she was surrounded by former and current students who wanted to pick her geological brain.
"For me as an instructor, I was really excited because students remembered learning about earthquakes in my class," she exclaimed. "They started gathering around me and pulling up on the their phones the U.S. Geological Survey (USGS) website I had told them about. It made a real connection for them. It was great to see them remembering and applying what they had learned in my class."
As the resident earthquake expert on campus, she said she's still getting emails and calls for answers. One alumnus, Matthew Zagursky, now a Philadelphia police officer, remembered the four science classes he had with Guertin as a student and came back to campus the next day to talk about plate tectonics. Other alumni are reaching out through Twitter.
Even the campus' Facebook page (www.facebook.com/pennstatebrandywine) was abuzz. "I thought the girl behind me [was] kicking my chair until everyone started freaking out," one student wrote.
"I was in my philosophy art and film class and all of a sudden the place started shaking," said another.
Guertin explained that the east coast of North America was once an active plate boundary and there are old fault lines from that boundary in Virginia and many that cut through the Keystone State. "We haven't been an active plate boundary since 245 million years ago, during the formation of the supercontinent Pangaea and the final stage of Appalachian Mountain formation. These mountains have been eroding away ever since," she said.
"This earthquake reminds us that we don't know what's coming. The faults that we think are inactive may not be. Earthquakes can occur at any time and we still have so much research to do to understand them."
Since the campus' seismograph is connected to the USGS's database, the activity recorded was a "key piece of information as they determined where the earthquake occurred," Guertin explained. That station picks up two types of signals. "When an earthquake occurs there are multiple waves of energy that expand from the hypocenter: a P Wave (Primary Wave), or compressional wave, is the initial low shaking back and forth in the same direction the wave was moving that everyone felt, and the S Wave (Secondary Wave), or shear wave, causes even more shaking perpendicular to the direction the wave is traveling, just as a snake moves side-to-side as it slides forward. Knowing the difference of time between when those two waves arrive at our station and other stations helps us calculate where the earthquake occurred."
Even students can act as "citizen scientists" and help determine the earthquake location and damage. The "Did you feel it?" page on the USGS website offers non-scientists a chance to contribute to a larger global database. "Our students can help scientists do their calculations and measurements in determining where the largest amount of damage occurred" by filling out a brief survey about what they felt and when. "What a wonderful opportunity for our students to study Earth in action and for scientists to learn from students."
As for the results of the seismograph's reading of the quake, Guertin said experts at University Park are still evaluating the data, but are "extremely happy with the clarity of the signal."
"Could another earthquake occur in Virginia or even Pennsylvania?" Guertin asked. Her answer was certain. "Absolutely! It's not a matter of 'if', it's a matter of 'when.'"
Penn State Brandywine Physical Plant assessed building conditions and determined that the campus sustained no damage, said Director of Business Services Lisa Yerges.
For more information on this and future earthquakes, visit http://www.earthquake.usgs.gov/ online.