While the earth moved in Boston and throughout New England yesterday, things quickly returned to normal and no major damage was reported. But that doesn’t mean Boston’s dense urban core is immune from earthquake damage.
Large swathes of Boston and surrounding areas are susceptible to "liquefaction," even from relatively small quakes, according to the Metropolitan Area Planning Council (MAPC), an Eastern Massachusetts regional planning agency.
Much of the city – including the Back Bay, large parts of the South End and Logan Airport – are built on "in-fill" land, created by piling earth and refuse onto former wetlands and tidal flats.
"Liquefaction is a process during an earthquake where certain kinds of earth materials absorb the shocks and vibrate in a manner similar to Jell-O," the council said in a statement. "This creates far more stress on any buildings constructed on these materials. Filled earth is most susceptible to liquefaction."
MAPC, with the help of the Massachusetts Emergency Management Agency, has developed a Pre-Disaster Mitigation Plan to help municipalities identify vulnerable facilities and infrastructure and minimize damage from earthquakes as well as other natural disasters.
The high-liquefaction risk areas include almost all the tunnels and earthworks erected as part of the Big Dig. Earlier this month, the state’s Department of Transportation revealed that a sink hole had developed under the Interstate 90 connector tunnel, caused by earth settling more extensively than engineers had predicted it would when constructing the tunnel.
"This kind of earthquake that we had yesterday was very large for an East Coast event," Martin Pillsbury, MAPC’s manager of environmental planning, told Banker & Tradesman. New England earthquakes are "not ever likely to be at the scale of magnitude that California faces. But on the other hand, we’re not built with withstanding earthquakes in mind. Historically, Boston was a thin little peninsula, and a huge amount of the city got built on fill over the last few centuries."
