Calculators in hand, a team of intrepid Yale scientists was standing by on Saturday when New Haven experienced a man-made earthquake.
As onlookers witnessed the demolition of the New Haven Veterans Memorial Coliseum, a seismograph — a machine that detects ground vibrations — recorded the effect of the collapse in the basement of Kline Geology Lab. Just one week before the event, Yale physics professor Steven Girvin organized a Yale Science Competition to see which student could most accurately predict how big an earthquake the demolition would cause.
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The “coliquake,” as it was termed by geology and geophysics graduate students Melissa Spannuth GRD ’10 and Garrett Leahy GRD ’08, was valued at approximately 1.0 on the Richter scale.
The contestants were required to write a short scientific paper identifying the key physics concepts and including a calculated prediction of the seismic effect. The contestants were to be divided into faculty, graduate and undergraduate categories, but only one team of graduate students — Spannuth and Garrett — and one team of undergraduates took on Girvin’s challenge.
Though both teams made estimates that were orders of magnitude too large, Girvin has declared each a winner in its category, saying that both teams put in a good effort to solve a sophisticated technical problem.
Spannuth said she was intrigued by the competition, as well as the thought of receiving a prize.
“It was kind of an odd and interesting problem that I wanted to work on,” she said. “And I really wanted to win.”
During the implosion of the 48,000-ton Coliseum, which was located on four and one-half acres of land, the ground supporting the building rebounded upwards, launching a series of low-frequency shock waves. The waves emanated outward and were ultimately picked up by the Yale seismograph. Some of the energy was absorbed by 15,000 tires trucked in by the Stamford Wrecking Company, the group responsible for overseeing the project.
The seismograph recorded velocities of the waves in three directions — east-west, north-south and up-down — and this data was converted to the Richter scale. The velocities indicated how much the ground at the seismic station moved as a result of the implosion. The vertical velocity, east-west velocity and north-south velocity were roughly 18, 35 and 16 microns per second, respectively. The signal was roughly four or five times greater than normal readings, which are usually two to three microns per second, geology and geophysics professor Jeffrey Parks said.
The prizes have not yet been awarded, Girvin said, but will probably involve a group dinner at a local restaurant. The undergraduate team consisted of Elissa Dunn ’09, Madeleine Udell ’09, Allison Kaptur ’09 and Elissa Berwick ’09.
Girvin attributed the small number of entrants to a lack of preparation time.
“I wish I had thought about it a little earlier so people could have had more time to think about it and enter,” he said.
There are approximately 8,000 micro-earthquakes — less than 2.0 on the Richter scale — each day. Construction site blasts and bombs often register activity on seismographs, in addition to geological phenomena occurring from within the Earth’s crust. The collapse of the World Trade Center marked a 2.5 on the Richter scale, Parks said.