Are you still wondering what shook the campus the afternoon of Sept. 16?
So are the experts. But you can help solve the mystery.
Christine Powell, professor of geography, is asking people to fill out "felt reports," describing what they felt at 1 p.m. that Tuesday afternoon when a boom shook the ground, registering 1.1 on the Richter scale.
And even if you felt nothing, Powell said she and the graduate student studying the event still would like your report.
Part of the mystery has been solved, Powell said. Analysis of readings from ground monitoring equipment demonstrate that the energy did not come from the air, eliminating such explanations as sonic booms, she said.
Hundreds of people already have used a web page to fill out felt reports, Powell said. You can fill out a report by going to the web site http://www.geosci.unc.edu/web/tremor.html.
More reports are needed from South Campu because that's where early analysis of seismographic data points, she said.
The source of the boom was underneath the Health Affairs area of campus, Powell said preliminary analysis of data showed.
Although demolition work has been going on there, Powell said UNC Hospitals physical plant officials have insisted nothing out of the ordinary was done that afternoon.
"Looking at the signals, we cannot yet determine if it was an earthquake or energy put into the ground," she said.
It's possible a small earthquake was triggered by a cumulative effect of the demolition work, Powell said. However, analysis of felt reports may shift the charted center of the event away from the hospital area, she said.
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