During the early morning hours of Friday March 25 an earthquake struck Lincoln Maine!

As dramatic as that sounds, most people probably didn’t even notice, perhaps paying little more attention to it than heavy construction equipment passing by a house close to the road. The windows on some Route 2 homes rattled slightly but dishes in the china closets were safe and sound. That’s because it only registered 2.2 on the Richter Scale, not anything close to the destructive power of the quake that struck Japan two weeks before. That quake and resulting tsunami were caused by the converging of two tectonic plates, something to really rattle the earth’s crust but an event we’re not expecting anytime soon in the Pine Tree State.

Beth Barton of the Maine Emergency Management Agency in an interview with this columnist the day of the Lincoln quake, observed that nearly all the quakes we do have register only in the one to two Richter range and that, “We have very few large magnitude earthquakes.” The biggest since 1747 was the 1904 Eastport/Calais quake. It would have registered somewhere between 5 and 6 on today’s Richter scale.

Barton explained that for one thing the soil types are “very rigid and rocky, not unstable” in addition to the fact that we are “not on the edge of a tectonic plate but are instead in the middle,” thus placing us at a low risk.

Barton also observed that there are no known active faults that run through Maine.

According to Spike Berry of the Maine Geological Survey most Maine quakes are in the central and eastern parts of the state with also a few in inland areas of York and Oxford counties. The four others we’ve had so far this year are in fairly typical locations: Machias, Eustis, Belfast, and Milo. All were between l and 2 on the Richter scale. The highly populated southern coastal portions of the state do not seem to be favorite targets of seismic activity even though in 1957 an earthquake did hit 20-miles offshore from Portland. Scattered reports of some split chimneys, cracked walls, broken windows and dishes in the area of Maine’s largest city were the outcome of that event.

Most earthquakes we do have in Maine are remnants of the Ice Age, which ended approximately 12 thousand years ago. During the height of that glacial age, ice and snow on top of the crust in New England reached up to a mile thick. This ice was so heavy that it pushed the earth’s crust down farther into the mantle than usual. When all the ice eventually melted at the end of this glacial condition, the continental crust rebounded back roughly to its original height. These are what geologists term “ isostatic” adjustments. We’ve been making them ever since.

The recent interest in earthquakes spurred by the traumatic Japanese experience coincides with the advent in Maine of its first state-wide building code. It’s one that took effect December 1 in 70 of the state’s largest cities and towns.

On the day of the Lincoln quake I also spoke to Rich McCarthy of the State Fire Marshall’s Office in Augusta. I asked him if the new code has any special provisions that render new construction in Maine more resistant to quakes.

According to McCarthy, the code as it applies to Maine has no enhanced features relative to earthquake resistant construction, besides the standard building code requirements. “We are not expecting anything would be a seismic event of a magnitude to cause an issue,” McCarthy told me.

The building codes are done by national regions so that, for example, there are additional snow roof weight load requirements imposed on Maine that aren’t found in southern states. These would, according to McCarthy, help avert the type of roof collapse that recently occurred at the Kennebec Hockey Arena in Hallowell.

But when it comes to earthquakes, Maine’s building code is what’s known as seismic design category “b,” which puts us in the “moderate ground shaking” level, the second lowest of the five classifications. By contrast, California is put in the much higher risk ranking of “e,” one that requires greater steel and other construction precautions in its construction codes.

Even though the new building code for Maine has nothing in it that prescribes special precautions for earthquakes, it’s vital to realize that all pre-December 2010 built structures in Maine are grandfathered and did not have to meet the current codes. To what extent are such buildings at risk?

On that score I spoke earlier this week with State Geologist Bob Marvinney. An earthquake in the magnitude of the largest we’ve seen in the last 264 years – the 1904 Eastport quake – would topple chimneys, brake windows, and crack plaster. Most potentially imperiled, according to Marvinney, are brick structures with unreinforced masonry, though even these would still be left standing, albeit damaged, in the event of an Eastport magnitude event. Better off but still at some risk are those with reinforced masonry. Wooden structures – because of the give and take of such premises – fare a little better. Steel structures are the safest.

Marvinney notes that with any modern day structure it’s most important that sills are firmly attached to its framing.

The possible vulnerability of parts of Maine’s older building stock has been a factor in Barton’s success in obtaining federal FEMA grants to help better prepare Mainers for earthquake related hazards. One for $49-thousand this year will be used to hire three interns to collect further data on earthquake related issues.

Thus, even though major earthquakes are unlikely events, Maine is not being completely complacent about preparedness for these potentially catastrophic occurrences.

This columnist is grateful for the assistance of

Mt. Blue High earth science teacher Patti Millette

Paul H. Mills is a Farmington attorney well known for his analyses a

and historical understanding of Maine’s political scene.

He can be reached by e-mail: [email protected]

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