Pitt Seismograph Detected Canadian Quake for 20 Minutes After Onset, Pitt Seismologist Says

Issue Date: 
June 28, 2010
Pitt's Allegheny ObservatoryPitt's Allegheny Observatory

The 5.0-magnitude earthquake that shook Toronto June 23 registered on the University of Pittsburgh’s seismograph for at least 20 minutes. Readings from the University’s seismic station at the Allegheny Observatory show the quake reaching Pittsburgh at approximately 1:43 p.m., two minutes after it reportedly began, and continuing to produce vibrations until 2:05 p.m., said Pitt seismologist and geophysics professor William Harbert, who oversees the seismic station. Although the quake’s magnitude is considered moderate, people reported feeling the quake in Pittsburgh and other areas in the Northeastern and Midwestern United States.

The quake’s center was 11 miles (or 18 kilometers) underground in the Western Quebec Seismic Zone, an area of rare seismic activity, Harbert said. The June 23 earthquake was a normal magnitude for this zone, he said, but the area has been the site of large earthquakes in the past, including a 6.1 in 1935 and a 6.2 in 1732. The earthquake also was typical of the smaller earthquakes usually felt in Pittsburgh and Western Pennsylvania.

Images from Pitt’s seismograph are available on the University Web site.

At http://www.pitt.edu/news2010/Rawdata.jpg, the image displays the hour on the left margin and the minutes on the bottom line. The earthquake is represented by the jagged lines that begin on the right side of line 17 and continue on the left end of line 18.

At http://www.pitt.edu/news2010/ExtractedEarthquake.jpg, the image displays the earthquake’s vertical displacement of the ground (the units to the left do not correspond to any particular unit of measurement).

Maintained by the Department of Geology and Planetary Science in Pitt’s School of Arts and Sciences, Pitt’s highly sensitive seismograph consists of a heavy steel canister that can detect as little as a half-nanometer-per-second displacement of the Earth’s crust caused by earthquakes anywhere in the world. Pitt’s seismic station—the region’s only one—unites Western Pennsylvania with a global network of scientists aiming to better understand the Earth’s structure.

Pitt feeds its earthquake readings into the public database of the Incorporated Research Institutions for Seismology (IRIS), a consortium of universities sponsored by the National Science Foundation that pools and analyzes seismic data. The station is identified on IRIS as “UPAO” and hooks into two IRIS networks: The “REALTIME” network of nearly 1,900 stations around the world that instantly displays earthquake data, and the “US-REGIONAL” network based at Pennsylvania State University that includes approximately 2,000 stations in the United States and Puerto Rico.

Pitt belongs to a five-station sub-network that also includes seismic stations at the Pennsylvania Geological Survey near Harrisburg, on the Penn State campus and at a Penn State substation outside of Philadelphia, and at North Carolina Agricultural and Technical State University. More information on and data from Pitt’s seismic station are available on the IRIS Web site at http://www.iris.edu/mda/PE/UPAO.