Merrimack New Hampshire Goes Seismic

You would not think of bucolic Merrimack, New Hampshire as being in the epicenter of

The public seismograph at the Merrimack (NH) Public Library. Photo courtesy of the library.

The public seismograph at the Merrimack (NH) Public Library. Photo courtesy of the library.

earthquakes–but it is now, sort of.  The town’s public library now (as of April 4, 2014) owns New Hampshire’s first and only public seismograph.  The Merrimack Public Library is also the first library to participate in the Boston College Educational Seismology Project (BC-ESP).

Because of the generosity of many donors, the library has completely paid for this project. I stopped in to make my own donation, and get a personal tour.

In case you didn’t know–a seismograph is a scientific instrument that detects and records vibrations (seismic waves) produced by earthquakes. A public seismograph means exactly that–you can walk into the library during normal business hours, proceed to the Lowell Room, and see the device, and learn about the project in real time.  In addition, the library will soon be offering educational training sessions for regular citizens of all ages and backgrounds (so I advise that you follow their web site for details).

News article: Thursday, November 18, 1756 New-Hampshire Gazette (Portsmouth NH) Issue 7, page 4

News article: Thursday, November 18, 1756 New-Hampshire Gazette (Portsmouth NH) Issue 7, page 4

The first major earthquake felt by our European ancestors in New England (no doubt New Hampshire’s indigenous people felt them long before that time) was [1 June] 1638, and was very severe, so much so as to throw persons to the ground.  In 1756 and 1757 two separate quakes were felt, but they caused no major damage. They did, however incite a few reads to write poetry and submit wonky  articles on the source of earthquakes.  In 1759 another news story proclaimed that in 1763 a great earthquake would herald in judgement day.

New Hampshire’s largest known earthquake took place in 1940 in the vicinity of Lake Ossipee.  The United States Department of the Interior, U.S. Geological Survey has compiled an earthquake history of New Hampshire., for the years 1663-1964.  The Weston Observatory at Boston College has a compilation of measurements for New Hampshire (and New England) taken between 2007-2014, and they have a web-based real time earthquake monitor.

On Friday July 15, 1757, the New-Hampshire Gazette (Portsmouth NH) Issue 41, Page 1, printed the following details on the cause of earthquakes.
To the Publisher of the New Hampshire Gazette. As a considerable Shock of an Earthquake was felt here Yesterday about two o’Clock P.M. preceded by a rumbling Noise; ’tis presumed the following Thoughts will not be unseasonable.
EARTHQUAKES are commonly preceded, and perhaps always attended , with a rumbling Noise; similar to Thunder; which has educed some to imagine they originated in our Atmosphere; either by an uncommon Rarefaction, or a Suspension of its Pressure on some Part of the Earth’s Surface. But the known Laws of Electricity (which solve the Phenomena of Thunder and Lightning) and the Effects which would necessarily ensue form a Suspension of the Atmospherical Pressure, with Respect to some Parts of the Earth, make it improbable. There be many Causes in Nature which acting, no other ways than by the Laws imposed on them by their Creator, capable, to produce such Effects as Earthquakes:–for since they are only Vibrations of Earth, ’tis evident, any Power in Naturing acting in such a Manner as to move any considerable Quality of this Earth, will produce such an Effect, in a great or less Degree. Water by Means of Fire is capable of great Rarefaction. If then a large Collection of Water should fall into a volcano in the Bowels of the Earth, and become rarefied, as one of the Lacrimae Vitrei, will in the Blaze of a Candel, it would undoubtedly produce all the Effects observed in an Earthquake. Again Water soaking into some heterogeneous Minerals, might cause such a Fermentation, and Explosion as has been observed of a Mixture made of Sulphur and Steel Dust with Water; the Consequence of which no doubt would be an Earthquake–But the most probably Cause is Air, whole Extreems of Rarefactions, and Condensation are almost if not quite infinite, which consist of such find Particles as to penetrate the Bowels of the Earth, and is dense the nearer to its Center, where some have supposed its Solidity, Density and Gravity little, if any Thing, inferior to Quick Silver. Air then dispersed in Caverns of the Earth would stand in Need of nothing more than a sufficient Degree of Heat, suddenly to expand it, to produce so tremendous Effect as an Earthquake–And that there is Fire in the Earth’s Bowels appears by Mount Aetna, Vesuvious and others–Also the fiery Eruptions which have been observed to attend Earthquakes, most strong evidence its Existance. Every Concussion of Air is an Occasion of Sound in a great or less Degree; therefore as the Atmosphere on all Sides gravitates and presses upon the Earth; tis impossible but that a Noise should be consequent, to a Concussion of the Earth. And if I mistake not, it has been observed, in Places which have been funk, little or no Noise has been perceived, previous to the sinking; the Reason of which I suppose to arise from the Earth’s shaking and Air’s vibrating then and there to commence: And places remote, a considerable Noise some Time before the shaking, because the Vibrations of Air being considerable swifter than those of Earth. If so ’tis probable the Place where an Earthquake first commenced might be known; by observing accurately the Seconds of Time from first hearing the Noise and perceiving the Shakes; provided the different Progress of Sound, and the Concussions of the Earth were ascertained–But least some may imagine the Cuase of Religion injured, by such Doctrine, which at first may seem to take off the Horror and Consternation such Phenomens throw Mankind into:–It may be observed that a Religion depending on a servile Fear, excited by such surprising Events; will be of short Continuance, and of but little Advantage to its Professors. Nor does it in the least derogate from the divine Perfections, to produce such Effects in a natural Way, and by natural Causes; but rather magnify and extol the great Author of the Universe. What greater Argument of the divine Power and Prescience than to order such a Coincidence of secondary Causes, at such and such particular Junctures of Time to awaken and alarm the stupid Sons of Adam.–Nay ’tis my Conjecture the Conflagration will arise form a Coincidence of secondary Causes, rather than by an miraculous Interposition of its Creator: At the destined Period of its Dissolution, perhaps these Flames which now assist in producing partial Concussions will cause a universal Shock, and no longer be confined within their present Limits, but belching forth, set this Earth on fire; to the Amaze and Surprize of its degenerate and abandon’d Inhabitants.

Kudos if you were able to get through the entire news article just above. I don’t know about you, but I’m glad to be living in an age where we are techno-savvy enough to know the true causes of earthquakes, but that they are mysterious,  dangerous, and unpredictable enough to intrigue and amaze us.



Merrimack (NH) Public Library

New Hampshire Earthquake Information – USGS

New England Seismic Network Blog

Boston College Educational Seismology Project

United States Seismic Zones Map – PDF

Real Time Feeds and Notifications for Earthquakes



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