28-01-2025
Could New England's 3.8 earthquake trigger aftershocks?
Earthquake felt off the coast of Maine
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On Appledore Island near the epicenter of Monday's earthquake, the Shoals Marine Laboratory cameras show the vibrations felt from the 3.8 quake.
Experts say one or more aftershocks are not out of the realm of possibility.
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John Ebel, a senior research scientist at Weston Observatory who studies seismic activity in New England, said that while Monday's event wasn't a large earthquake, there is a window for a few more jolts to surface. 'The larger the earthquake, the larger the window for aftershocks. For a magnitude 4.0, it's like two weeks; for a magnitude 7.0, it's a few years,' said Ebel, who has
Aftershocks are a sequence of earthquakes that occur near the epicenter of a quake or proximity to where the main 'rupture' in a fault line occurred, and are part of the readjustment process after the fault initially gives way, according to the United States Geological Survey.
Not only can aftershocks occur but the chances of one happening decreases over time from the initial rumble, according to experts.
In its 'aftershock forecast,' the USGS noted that chances are rather slim, about a 9 percent shot, that this York Harbor tremor will produce a magnitude 3 or higher aftershock that would be felt.
The USGS said: 'Typically, there are aftershocks with earthquakes, even in New England, but they'll likely stay at or slightly below the threshold for people to feel the shake, which is around 2.5 or 2.8 or less,' as measured on the Richter scale, which ranges from 1 to a magnitude of 10, a catastrophic quake.
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Sophie Coulson, assistant professor in Earth Science at University of New Hampshire, said aftershocks are usually weaker than the initial event, so any aftershock resulting from this recent earthquake would be less than a 3.8 magnitude and rather indiscernible.
'Certainly, (aftershocks) could be happening over the next couple days, but these would likely be much smaller events that we wouldn't even necessarily feel,' Coulson said.
Geology professor Tasha Dunn at Colby College said the Northeast experiences earthquakes 'on a fairly regular basis that are really, really teeny tiny. So, it might honestly be difficult to distinguish aftershocks of this earthquake from other earthquakes that are, you know, just going on on a regular basis.'
During Monday's 3.8 quake, Coulson said her students saw projectors shaking and pictures on the walls moving slightly during Monday's event. In her lecture class of about 80 students, she said most felt the tremor.
Ebel believes that because of our limited seismic activity across New England, we are better able to keep track of aftershocks compared with our neighbors out west. 'Here that activity is so low, we probably can observe aftershocks for many years after moderate-size earthquakes,' he said.
Some experts believe the York Harbor quake most likely occurred in an area known as the Norumbega Fault Zone, a major 'strike-slip fault' area located in coastal Maine.
Ebel, however, suspects the earthquake's epicenter happened in a region more offshore that has been seismically active since the 1970s. 'If you go to Cape Ann, and you go to the east maybe 20 or 30 miles, and from there you go north toward York, Maine, over the last five decades or so, there have been a number of earthquakes detected in that zone.'
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While there is not enough evidence to convince all seismologists that it is an active fault, Ebel said, 'my opinion is, actually it probably is.'
'There are three or four faults in the Newburyport area that are 400 million years old,' said Ebel. While scientists have no evidence that those faults are active, there are still a lot of mysteries when it comes to ancient faults.
'Figuring out how the modern earthquake relates to the old faults is a conundrum that we are trying to work out.'
Amanda Gokee can be reached at
