Thursday, May 19, 2011

Guest Post - Tiny Earthquakes in Maine: From the Last Ice Age

I have another guest post for you today. This time we have Mariana Ashley focusing in on what the hell is going on in Maine and why do they have so many tiny earthquakes.

Earlier this month, Maine experienced a swarm of tiny earthquakes. In the first week of May, Maine was hit by as many as 30 minor tremors. These tiny earthquakes, which were all below magnitude 2, were not big enough to be felt although residents did hear them; many were reported as sounding like gunshots.

As many of you know, Maine is not on any active fault line; in fact, Maine is right in the middle of a plate. However, despite Maine's tectonic position, Maine still experiences some stresses and responses to the movement of the tectonic plate it's on.

Maine is also experiencing some after-effects of the last Ice Age. About 13,000 years ago, the area of Maine and New England was covered by an enormous amount of ice; this ice weighed a ton and depressed the crust in Maine by about 500 feet in some areas. The ice melted relatively quickly in relation to geologic time, and the crust is still responding to that loss of weight.

The stress from that loss of weight is released from tiny faults over the state. These faults are usually 100 feet wide and about a mile deep. They are located all over Maine, around mountains and the coast as well.

Normally these tiny earthquakes, in response to a change of weight or pressure of the crust, are more spread out and hardly noticeable, sometimes not even documented. Scientists are still trying to determine exactly why they swarmed in such close intervals in Maine. There have been two other records of tiny earthquake swarms in Maine, one in 2006 and another in 1967. Since they are so rare, scientists don't have a good answer why so many tiny earthquakes would occur so frequently in one location.

While there's no great explanation for the swarm of earthquakes in Maine, scientists don't believe this is anything to be worried about. This type of seismic activity is in no way a warning sign, and since nobody in Maine could actually feel the quakes, not many people are taking it as one either. If anything, this is just an interesting reminder that landscapes are a lot more complex than most people think; landscapes are constantly responding to forces and events that occurred far beyond our own lifetimes.

Mariana Ashley is a freelance writer who particularly enjoys writing about top online colleges. She loves receiving reader feedback, which can be directed to mariana.ashley031

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