The earth shook in Philadelphia at 1:55 p.m. Tuesday, Aug. 23, but a sampling of Northwest residents polled in the Mt. Airy business district shortly after the earthquake said they weren’t shaken up much at all. In fact, more than one of those interviewed said they hadn’t even noticed the temblor, which measured 5.9 on the Richter scale near its epicenter when it struck central Virginia at 1:51 p.m. The ripples of the quake were felt up and down the East Coast, from Georgia to New England and Montreal, Canada.
Among them was Mark Kidd, proprietor of Majeki’s Stain Glass at 7212 Germantown Ave. Every surface in Kidd’s shop is piled high with equipment and materials that he uses in his custom stained glass business. Gazing around the premises he said, “You’d sure think that something would have rattled but I didn’t feel a thing.” He didn’t know about the quake until someone called and told him about it.
Paul Richards was en route to the Mt. Airy Farmer’s Market in William Allen Plaza with a truck of produce from New Jersey when the quake hit. “We were in the truck driving and didn’t feel a thing,” Richards said.
Local geography matters
The reasons that the city’s northwest neighborhoods seemed relatively unaffected compared with other sections may have something to do with the composition of the ground and the nature of the building stock, according to Jean Gajary, a structural engineer who lives in Mt. Airy.
“The stiffer and rockier the ground, the less you have to design for earthquakes,” Gajary said. She added that the Northwest’s ground is rockier than that in Center City and South Philadelphia.
Locations like the former Philadelphia Navy Yard, where much of the ground is made up of fill dirt are very different. Fill can liquefy in the event of a quake, losing its ability to support a structure. “If you are designing a building there,” she said, “seismic forces are in control.”
Built like a rock
The Northwest’s building stock, which is largely composed of stone and brick buildings, also had something to do with mitigating effects of the quake because such buildings are “stiff” and don’t sway much, she added. For example, Mark Kidd’s premises shares walls with buildings on either side, which likely buttressed it and kept it from moving at all, she said.
In contrast, steel-framed high rises such as those in Center City have plenty of give to them, and they can sway much more easily. “People in the upper floors feel them move,” said Gajary. “Steel moves a lot – it’s considered a flexible material by engineers.”
While some interviewed for this article didn’t notice the earthquake, others said they were aware of the shaking but didn’t quite know what it was at first.
Patrons at McMenamin’s Tavern, 7170 Germantown Ave., said they felt nothing but realized something was happening when the TV set behind the bar swayed from side to side.
Mt. Airy resident James Murphy was sleeping when the earthquake woke him up. “I thought somebody was shaking the bed,” he said. “I even looked under the bed to see if anyone was there.”
Cynthia Mason of Mt. Airy thought her next-door neighbor might be doing some work on his house. She realized it was an earthquake when she went outside. Pointing to her baby daughter Julianna, whom she was walking in her stroller, Mason said, “She slept through the whole thing.”
How can this be happening?
Mt. Airyite Mark Geiger was in the shower after a workout when the walls started to shake. “I thought I was having a stroke or something. You don’t expect [an earthquake] here.”
“We don’t have earthquakes in our consciousness on the East Coast,” said Susan Bloch of East Sedgwick Street. However, she added, “My first thought was, ‘It’s an earthquake.'” The first clue was her washing machine, which sometimes shakes the house. She glanced at the smoothly-running machine and felt sure that a quake had struck.
Another who was certain was Harvey Quarrels, who was with his wife in the basement of their West Oak Lane home at 1:55 p.m. “The ground was shaking and chairs were rattling. I knew it was a quake,” Quarrels said. He added that he has friends who live in Culpepper, Va., not far from the quake’s center, and would be calling to check with them.
In the wake of the essentially minor drama of the quake, wondered Geiger, “I wonder how long it will be until somebody ties it to fracking [the controversial Marcellus Shale natural gas extraction method]. The conspiracy buffs are going to start coming out of the woodwork.”