Historic Earthquakes

Near Ossipee Lake, New Hampshire
1940 12 20 07:27:26.2 UTC
Magnitude 5.50
Intensity VII

1940 12 24 13:43:45.0 UTC
Magnitude 5.50
Intensity VII

Largest Earthquake in New Hampshire

The first earthquake on December 20 and one of about the same intensity on December 24 are described together. Their epicenters lie in the same general region west of Whittier, New Hampshire. Although the second shock was of less duration, it was somewhat more intense than the first. However, the first shock undoubtedly weakened structures, which resulted in more severe damage from the second earthquake.

The town of Tamworth, on the edge of the Ossipee Mountains in central Carroll County, sustained the most damage. Old houses and chimneys in need of repair were most commonly damaged. Some chimneys were thrown down, and 20 others were damaged. Also, reports indicate that well water remained muddy for several days and that many cracks formed in the crusty snow. Other minor damage included cracked walls, broken water pipes, fallen plaster, and broken furniture.

At the Riverside Cemetery at Whittier, about 3 kilometers south of Tamworth, five monuments were displaced. In the nearby towns of West Ossipee and Chocorua, many old chimneys in need of repair were damaged, and water in wells became muddy. At Wonalancet, 8 kilometers northwest of Tamworth, the foundation of an old house (constructed of heavy timber) was damaged when it shifted about 30 centimeters. Heavy furniture, including a kitchen stove, moved several centimeters across the floor.

Minor damage occurred at several towns in Maine, Massachusetts, New York, and Vermont. Reports of the shock also were received from Connecticut, New Jersey, Pennsylvania, and Rhode Island, as well as from Montreal and Quebec, Canada. Several small aftershocks occurred over the next several months.

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.