Quake village's first in nearly 80 years
Published Tuesday March 10th, 2009
MONCTON - Scientists say the small earthquake that shook Doaktown early Sunday was the first in the village in almost 80 years.
While Doaktown, population 888, has been shaken by earthquakes originating elsewhere in the province, the last time the village was at the epicentre of the earth's rumble was in 1930.
Since 1980 there have been only 13 events larger than a Richter Scale magnitude of 4.0 within 100 kilometres of Doaktown.
Sunday's shake registered between 3.4 and 3.6.
Kenneth Burke, a retired geophysical consultant, professor and author on earthquakes, said Monday the village has only three previous earthquakes on record.
"Normally we will get a magnitude three in the province maybe one or two a year, if that," Burke said.
"A magnitude more than four - once every 10 years, a magnitude five - every 50 or 60 years."
Sunday's activity can now be added to newspaper clippings recalling seismic activity in Doaktown in 1930, 1911 and 1883.
Small earthquakes unnoticeable to the public happen regularly in the province, Burke said. Doaktown actually experienced two earthquakes on Sunday and potentially several small aftershocks. The first was at 5:16 a.m. with a magnitude of 3.5 and a second at 10:30 a.m. of 3.2.
Earthquakes with a magnitude of more than three can be felt. Earthquakes over a magnitude of five can cause structural damage to buildings.
Hundreds of tremors have been recorded in New Brunswick, which lies within the Northern Appalachian zone.
"It's an area that has seen seismicity in the past," said Sylvia Hayek, a seismic analyst for EarthquakesCanada, which tracked Sunday's earthquake. "That general region has seen a fair amount of small activity."
The Miramichi region was brought to the attention of the seismological community by a 5.7 earthquake on Jan. 9, 1982. The quake shook the majority of the province and was felt as far as Maine, New York and Pennsylvania.
"It's not like the West Coast where you have this major fault running offshore due to tectonic plates," Hayek said.
"New Brunswick is in the middle of a plate so generally it's considered relatively stable, with some areas that generally have more activity than others."
Hayek said it appears that ancient geological incidents, such as a failed rift or a meteorite impact, may have made some Atlantic areas more prone to earthquakes than others.
Earthwuakes occur when the earth's tectonic plates shift. The North American plate is moving away from those covering Europe and Africa in the centre of the Atlantic Ocean.
"That is very, very slowly squeezing the North American plate," said John Ebel, a director of the Weston Observatory of Boston College.
"Much as if you were to take a brick or piece of rock and put it into a vice and just very slowly turn the crank. You can't squeeze rock forever before it cracks in places."
The Doaktown earthquake, plotted at 86.2 kilometres north-northeast of Fredericton, was also followed by the New England Seismic Network at the Weston Observatory.
The observatory operates a series of seismometers throughout New England, but also picks up activity in New Brunswick. It recorded readings similar to EarthquakesCanada's on Sunday.
"There certainly is the potential for damaging earthquakes in New Brunswick because where you do have fairly persistent small earthquake activity, you do have a chance for larger earthquakes and you do have that historically in New Brunswick," Ebel said.
"I would love to be able to predict them, but unfortunately there is no credible seismologist in the world who knows how to predict earthquakes at this point in time. We're as surprised as the rest of you when an earthquake does occur."
"There will be one magnitude five earthquake in New Brunswick within the next century, I'll say that," Burke said. "When, I don't know. But it seems that's how history goes."
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