Today’s magnitude 4.8 earthquake was centered in New Jersey, but it could be felt hundreds of miles away — as far north as Maine, and as far south as Virginia.
Many across the Cape, Coast, and Islands reported their homes shaking.
In part, that’s because seismic waves — the thing you feel shaking during an earthquake — can travel faster and further through the ground on the East Coast than they can on the West Coast.
William Barnhart, a geophysicist with the U.S. Geological Survey (USGS), says the rock beneath our feet is much more cohesive than it is in a place like California.
“So think of a nice, freshly forged bell that you would ring. If you ring that, it rings for a really long time,” he said. “Whereas if you had like a cracked bell or something like that, it wouldn't ring for as long.”
What’s more, the Cape region is region is made up of sandy soil, which acts like a trampoline for seismic waves.
“So you get stronger shaking there than, say, if you were further west and in the Berkshires on hard rock,” Barnhart said. “If you're on hard rock, you wouldn't feel the shaking as strongly as you would if you're on sandy sediments.”
Some locals reported confusion over why their neighbors felt the quake, but they didn’t.
Barnhart said whether one individual noticed shaking beneath their feet has to do with a variety of factors: what type of structure they were in, what kind of ground the structure is on, and how strong the foundation is.
Those in a bed on the tallest story of a building were more likely to feel the quake than those in a car, for example.
No local damage reported
The Cape’s emergency management department said no major impacts have been reported.
“The Cape Cod Canal bridges were inspected earlier today following the earthquake that occurred this morning. Our experts observed no damage or issues on the Canal bridges, and all the bridges remain safe and open for travel,” according to Bryan Purtell, a public information officer from the U.S. Army Corps of Engineers, New England District, in a statement to CAI.
The hurricane barriers at Fox Point and New Bedford were also inspected, he added, and no damage was observed at either project.
Chip Reilly, the emergency preparedness director for Barnstable County, conveyed similar news: he said the effects of the earthquake across the region have been minor, but he’s continuing to communicate with towns and monitor the situation.
“We have no reports of any major shaking, any major structural damage to anything, or anything of that nature. But it just keeps us aware that all kinds of emergencies can happen,” Reilly said.
Reilly urged people to prepare for emergencies by building a survival kit, making a plan and being informed.
“We've just come through winter storm season, and while we take a sigh of relief as we're out of our snowstorms, theoretically we're coming up on hurricane season,” he said. He added, “We never said that we would see tornadoes on Cape Cod. We've seen a few over the last couple of years—so that ‘all-hazards planning’ is really a year-round thing.”
Caution urged as more aftershocks possible
Since 1950, 40 other earthquakes magnitude 3 or larger have occurred within 155 miles of today's quake, USGS officials said. One East Coast earthquake, in 2011, reached a 5.8 magnitude.
This magnitude 4.8 earthquake, which occurred around 10:30 a.m., has been largest since 2011, with millions feeling it.
“We currently have over 100,000 reports to our website describing the shaking they felt,” Paul Earle, a seismologist from the USGS National Earthquake Information Center, said shortly after noon.
For scale, the earthquake that happened in Taiwan recently had a magnitude of 7.4, and it released 2,000 - 3,000 times more energy.
Overall, experts concluded, earthquakes in this region are uncommon, but not unexpected. Nor are aftershocks. As of 2:30 p.m., at least two have been reported.
“It's likely that people are especially near the epicenter or are going to feel aftershocks for this earthquake in the magnitude 2 to 3 range,” Earle said. “And there's a small chance that there can be an earthquake as large, or larger, following an earthquake like this."
USGS officials said they’re still looking into the overall cause.
“Although there are no known active faults mapped in that area, there are dozens of older, inactive faults that formed millions of years ago,” said Jessica Jobe, with the USGS Earthquake Hazards program. “And under the current stresses from tectonic plates moving, those faults can be intermittently reactivated. And so our current understanding is that that may have occurred during this earthquake.”
She said they need to do more work to “discover the causative fault and understand more of the tectonic processes behind this event.”
