While New Hampshire, along with the rest of New England, does not frequently experience earthquakes, it has experienced several earthquakes in its history, and has been affected by some of the larger earthquakes centered in the St. Lawrence Valley seismic zone in Canada and in a seismic zone in northeastern Massachusetts. All of New England felt the 1663 Charlevoix earthquake centered near the Quebec-Maine border, the magnitude of which has since been estimated at 7.3-7.9. In 1727, Newbury, Massachusetts, received a damaging earthquake, shaking New Hampshire. The 1755 Cape Ann Earthquake, estimated magnitude 5.5-6.0, also shook most or all of New Hampshire. On November 9, 1810, Exeter experienced an estimated intensity VI tremor. It was accompanied by an unusual noise like an explosion below the area and broke windows in Portsmouth. Concord, the capital, experienced a series of shocks within a period of 19 years, 1872 to 1891. One earthquake was felt in late 1872, lasting 10 seconds in Concord, and was felt in Laconia and other towns to the north. Ten years later, another tremor was strongest in Concord, although Dover and Pittsfield reportedly had buildings shaken. On November 23, 1884, two earthquakes, the first one light, followed fifteen minutes later by a severe one, were both felt in Concord. The second shock was felt in Massachusetts, Connecticut, and eastern New York. Concord’s last tremor in the 19-year period was mild and was reported in two Massachusetts locations: Cambridge and Melrose.
Southeastern New Hampshire and Maine experienced an earthquake in 1925. Both were moderately damaging. Dishes and goods were thrown from shelves in Ossipee, Tuftonboro, and Effingham Falls. In 1929 the Grand Banks of Newfoundland, 800 miles (1,300 km) away, experienced a magnitude 7.2 earthquake, and New Hampshire had minor effects. In 1935, a 6.25 earthquake centered in Timiskaming, Ontario, 500 miles (800 km) away, was felt in an area of over 2,500,000 square kilometers (970,000 sq mi), and New Hampshire recorded intensities of 5.0 in some places. Ossipee Lake in December 1940 was the site of two moderate earthquakes. It was felt in all six New England states, as well as parts of New Jersey and Pennsylvania. In the epicentral area, a large number of aftershocks happened. One observer counted over 120 aftershocks through January 31, 1941.