Geoscience Reference
In-Depth Information
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“
On November 18, 1755, the earth beneath the waters off Cape Ann heaved. Within seconds, the seis-
mic wave generated there traveled to the twisting lanes and wharves of pre-Revolutionary Boston.
According to historical accounts, chimneys toppled from roofs, steeples parted from churches, and
gables crumbled from building fronts and shattered on the lanes below. The weather vane atop Fan-
euil Hall snapped. Vibrations were felt from Halifax, Nova Scotia, to Chesapeake Bay. Estimated at a
magnitude of 6.2, the Cape Ann earthquake is one of New England's strongest in recorded history.
But it's not the aberration you might think. In an average year, 30 to 40 earthquakes strike New Eng-
land. . . . In 1929, a magnitude 7.2 quake centered off the southern coast of Newfoundland generated
a tsunami that killed at least two dozen people; the quake was felt as far away as New York City.
A study by Boston College seismologist John Ebel, published earlier this year, zeroes in on the epi-
center of the 1755 Cape Ann earthquake. Ebel, who has spent the last 25 years studying local quakes,
also proposes a new idea: that all New England earthquakes—including the 1755 one and a 1638 mag-
nitude 7 quake probably centered in New Hampshire—might be the aftershocks of an even larger his-
torical quake. He says another large one may be looming. Our earthquake threat is made more press-
ing by what distinguishes Boston among other American cities: its elegant brick-and-mortar architec-
ture, which in many cases sits on lose, unstable soil. . . . Yet earthquakes do happen here. Why then
isn't Boston ready for the next one?
”
—Jeremy Miller, “Boston's Earthquake Problem,”
The Boston
Globe
, May 28, 2006
Given the series of devastating earthquakes over the past few years, ranging from the mega
quakes in Japan, Chile, and the Indian Ocean tsunami, to the smaller but still deadly quakes in
Kobe and Haiti, people are concerned that we are entering a period of heightened global seis-
mic activity, and that means they should be prepared for potential earthquakes even if they live
in an area that has been relatively free of quakes in recent history.
Most Americans think earthquakes are only a problem in California and possibly Alaska,
but that isn't necessarily the case. Realize that earthquake predictions are based on statistical
averages. Living in an area that is not known for earthquakes does not mean you won't ever ex-
perience a major earthquake. What it does mean is that you have a smaller chance of experien-
