Before dawn on November 18, 1755, an earthquake struck some 30 miles east of Cape Ann.

In Boston, chimneys and gabled roofs toppled to the ground and church steeples tilted. Some streets were filled with piles of brick that made them impassable. The 3.6 magnitude (on the Richter scale) earthquake on November 8 in Buzzards Bay off New Bedford caused little damage compared to that from the estimated 6.2 magnitude earthquake 265 years ago, geophysicists say that the region is due for another substantial tremblor sometime soon. “If a 5.5 [magnitude earthquake] happens tomorrow in Buzzards Bay, that wouldn’t surprise me,” said John Ebel, a professor of geophysics at Boston College. “Because sooner or later you have to catch up with the long-term average of statistics.”

Ebel says that earthquakes with a magnitude of 5 or slightly higher, which is usually the threshold for significant damage, occur, on average, every 80-100 years in New England.

Of course, more severe quakes happen even less frequently. In 1940, a 5.6 magnitude tremblor that knocked over chimneys in New Hampshire’s Ossipee Mountains was felt in Boston but caused no appreciable damage there.

Since 1975, when detailed earthquake measurements began being recorded in New England, there haven’t been any earthquakes recorded under the city itself, according to Ebel. But the possibility exists. “[The past epicenters] kind of ring around Boston,” Ebel said. “That could change though… Our earthquakes aren’t large enough to crack the ground’s surface,” he added. “So we don’t know the patterns of active faults in the region.”

After the November 8 earthquake, insurance brokers noticed an uptick in clients interested in buying earthquake insurance, which is sold separately from homeowner or business insurance as an endorsement.

“We’ve received quite a few calls as a direct result of the little earthquake,” said George Doherty, president of Corcoran and Havlin Insurance Group, a broker based in Wellesley with clients in Boston.

“Small earthquakes can leave their mark. What is of some concern from a risk standpoint is if there were to be an earthquake in the Greater Boston area, there are a few neighborhoods that are particularly vulnerable.”

Boston was founded on a narrow peninsula, but its size has been greatly expanded over the years, mostly in the 19th Century, by using mud, sand and trash to fill land around the watery edges of the old, core city. Back Bay, the South End and South Boston are built on this landfill.

During an earthquake, Doherty said the landfill can vibrate “like Jello.”

“Soft soils like river sediments and landfill tend to amplify ground shaking more than the ground shaking on hard rock,” Ebel said.

Because neighborhoods built on landfill are at higher risk, earthquake insurance in those areas costs more than in areas built on more stable foundations. Boston’s historic neighborhoods are also vulnerable to earthquakes because of their age.

But Doherty maintains that earthquake insurance in the Boston area is affordable. A $1 million home’s earthquake insurance could cost between $550 and $750 annually, he said.

Since the 1970s, building codes in Boston require new structures to be able to withstand the shaking of 5.5 to 6.5 magnitude earthquakes, according to Eric Hines, a professor of engineering at Tufts University.

Older buildings, when renovated, are required to be reinforced against earthquakes.

“As our old buildings get replaced with new buildings, we’re actually becoming safer and safer,” said Ebel.

Still, between 40% and 60% of the buildings in Boston that pre-date 1970s building codes have not been renovated, Hines said.

Older masonry buildings are brittle and so more likely to collapse.

Living in a region with moderate seismic risk, Bostonians have trouble adequately preparing for an event that is unlikely but expensive to mitigate.

“Boston has been working as diligently as anybody in the world to ensure that [the city is] safe,” Hines said. “But we live this double life where we say we have to design for earthquakes, but we can’t spend the money,” he said.

And one day, another damaging earthquake is coming.

“People feel vulnerable after an incident like Sunday, and it’s a reminder that it can happen. A lot of people haven’t really paid attention to that peril before,” Doherty said. “But most people in New England are not living in fear of an earthquake and feel they’re going to roll the dice and continue on without the coverage.”