In addition to tremors originating within the State, New Hampshire has also been affected by some of the stronger earthquakes centered in the St Lawrence Valley seismic zone and in the northeastern Massachusetts seismic zone.
On February 5, 1663, a major earthquake centered in the St. Lawrence River region was felt over all the settled areas of eastern Canada and northeastern United States. Because of the sparse population at this early time in Colonial history, accounts of the earthquake are far from definite. However, the shock was felt sharply in New England. At Massachusetts Bay, houses were shaken, pewter fell from shelves, and chimneys were broken or thrown down. The affected area undoubtedly include New Hampshire.
A damaging shock at Newbury, Massachusetts, in 1727 probably affected towns in New Hampshire.
A September 16, 1732, earthquake centered in the St. Lawrence Valley was felt at Piscataqua. The shock was centered near Montreal, where several hundred houses were damaged.
A major shock on November 18, 1755, centered east of Cape Ann, Massachusetts, caused extensive damage at Boston. The felt area included most of New Hampshire.
On November 9, 1810, Exeter, New Hampshire, was strongly shaken by an intensity VI earthquake. The shock was accompanied by a very unusual noise like a great explosion directly beneath the area. Windows were broken in Portsmouth and a vessel in the harbor seemed to strike bottom. The shock was also felt in Maine at Kennebunk and Portland.
The area around Concord experienced a number of shocks between 1872 and 1891. Two moderate earthquakes, the first on November 18, 1872, and the second on December 19, 1882, were felt at Concord. The first shock, described as lasting only 10 seconds, was felt in adjacent towns and at Laconia, 50 kilometers to the north. The 1882 tremor was strongest at Concord, although buildings reportedly shook at Dover and Pittsfield. The town of Contoocook, near Concord, reported an earthquake of moderate intensity on January 18, 1884. On November 23, 1884, two more earthquakes, the first a light shock, followed 15 minutes later by a heavy one, were felt at Concord. Nearby, at Henniker, the foundation of a boiler was displaced. The second shock was felt over an area of about 20,750 square kilometers including eastern Massachusetts, Connecticut, and eastern New York. Concord again experienced a mild tremor on May 1, 1891. The earthquake was reported felt at Cambridge and Melrose, Massachusetts.
Moderate damage occurred in southeastern New Hampshire and adjacent portions of Maine from an earthquake on October 9, 1925. Chimneys were thrown down at Cornish, Maine; dishes were thrown from shelves at Ossipee and Tuftonboro, New Hampshire, and goods fell from shelves at Effingham Falls. Many were frightened at Laconia. On March 18, 1926, a tremor centered near Manchester occurred. Buildings rocked and a few dishes fell at New Ipswich. Intensity V effects were also observed at Amherst, Lyndeborough, Manchester, Mason, and Wilton. A small, localized shock was felt at Concord on March 8, 1927. Dishes rattled and rumbling sounds were reported. This disturbance was felt lightly in Cheshire and Hillsborough counties.
Northern New Hampshire and nearby parts of Maine and Vermont experienced a moderate earthquake on April 25, 1928. The shock was felt over a line extending 145 kilometers from Lewiston, Maine, to St. Johsbury, Vermont. Berling and Gorham, New Hampshire, were apparently closest to the epicenter. The shock was described as "violent" in some paces, although little damage was done.
All of New Hampshire felt minor effects from a magnitude 7.2 earthquake on November 18, 1929. Historically known as the “Grand Banks” earthquake, the event was located about 250km south of the Burin Peninsula of Newfoundland. Another strong, distant earthquake affected the State on November 1, 1935, when a magnitude 6.25 shock occurred near Timiskaming, Canada. Damage was relatively slight in the epicentral region, largely because of the sparsity of population. The November 1 earthquake was felt over an area nearly 2,600,000 square kilometers in the United States and Canada. Intensity V effects were reported from Keene, West Manchester, and Woodville; many other places within the State reported this shock.
Two earthquakes, 4 days apart, centered near Lake Ossipee on December 20 and 24, 1940, caused damage over a broad area. Since the shocks were both of approximately the same intensity, the damage and felt reports were combined. Damage resulting from the second tremor was greater because of the weakening effects of the earlier shock. A maximum intensity of VII was noted at Tamworth and Wonalancet, where chimneys were thrown down, some walls were cracked, plaster fell, and a few pipes were broken. Much stucco was knocked loose from outside walls. Some furniture was also broken and there was considerable damage to china and glassware. There was evidence of ground cracks in the region near the two towns. The earthquakes were felt as far as 550 kilometers from the epicentral area and affected a total land area in the United States of approximately 390,000 square kilometers. This included Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont and also parts of New Jersey, New York, and Pennsylvania. A large number of aftershocks were reported in the epicentral area. One observer counted 129 aftershocks through January 31, 1941.
An earthquake, on June 26, 1964, reached intensity VI at Meriden (fallen plaster) and caused slight damage at Bradford, New Hampshire, and Springfield, Vermont.
Abridged from Earthquake Information Bulletin, Volume 7, Number 1, January - February 1975, by Carl A. von Hake.
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