A 1.7-magnitude earthquake shook Manchester, N.H., Friday morning, a rather infrequent event for the New England area, researchers said.
Scientists at the Boston College Weston Observatory detected the small earthquake around 9:54 a.m. just 4 miles north-northeast of Nashua, N.H., said Dr. John Ebel, a senior research scientist at the observatory.
Ebel said some residents from Pelham, N.H., and Dracut, Mass., told him they heard a boom and felt a brief shake, which is typical of an earthquake this size.
“This earthquake was well below the level of which any damage would have occurred,” said Ebel, who is also a geophysics professor at Boston College.
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“Earthquakes with magnitudes around 5.0 and the upper 4s are considered the threshold for damage.”
Such damage includes structure collapses, cracks in walls, and chimney knockouts, Ebel said.
The Northeast is no stranger to earthquakes, as small as they may be.
Ebel said the observatory detected an earthquake in New Jersey about a month ago and another in Pennsylvania sometime last week.
The most famous earthquake to have occurred in New England was the Cape Ann earthquake in Massachusetts in November 1755, reaching a magnitude of about 6.25, Ebel said.
This is considered the largest earthquake in the state’s history.
New England, however, doesn’t compare to California, Ebel said.
The number of earthquakes California records in one year will take New England about 100 years to match, Ebel said.
The reason being that the West Coast has many more faults — locations under the earth’s surface where rocks break or crack, which spark a release of energy largely known as an earthquake, Ebel said.
These faults are considered zones of weakness, Ebel said, and New England lacks a significant amount of them for the area to be earthquake prone, like California.
But it is always better to be safe than sorry, Ebel said, because researchers cannot predict when earthquakes will occur.
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Ebel said research indicates earthquakes show no preference for season, weather types, or solar cycles, making their surprise visits even harder to understand and predict.
“You should just know the fundamentals of safety for earthquakes,” he said in the case of a serious earthquake.
“People are usually hurt by things falling on them, so get under a heavy piece of furniture and get away from any objects that can fall on you.”
If protecting yourself under furniture is not an option, Ebel advised to do what is called the “drop, cover, and hold,” in which you curl up in a ball and cover your head with your hands to protect yourself from falling objects.
Correction: An earlier version of this story incorrectly stated the date of the Cape Ann earthquake. It occurred in 1755.
Katie Camero can be reached at katie.camero@globe.com. Follow her on Twitter @camerokt_.