1940 New Hampshire earthquakes

1940 New Hampshire earthquakes

Date	20 December 1940 (1940-12-20)
Origin time	7:27 UTC ^[1]
Magnitude	5.3 M_w ^[1]
Depth	10 km (6.2 mi) ^[1]
Epicenter	43°50′N 71°17′W / 43.83°N 71.28°W / 43.83; -71.28 ^[1]
Type	Unknown
Areas affected	New England United States
Max. intensity	VII (Very strong) ^[1]
Aftershocks	5.6 M_w Dec 24 at 13:43 ^[1]

Isoseismal map for the 1940 New Hampshire earthquakes

The 1940 New Hampshire earthquakes struck on December 20 and again on December 24. The initial shock measured 5.3 and the second shock measured 5.6 on the moment magnitude scale. With a maximum Mercalli intensity of VII (Very strong), these doublet earthquakes were the largest to hit the state. Damage included minor fractures or knocked over chimneys in a zone extending through New Hampshire and four other states: Maine, New York, Vermont and Massachusetts.

History

While not known for earthquakes, New Hampshire has been dotted with both major and minor events. The first recorded significant event to strike the state was the 1663 Charlevoix earthquake, originating in the Saint Lawrence River fault zone. The extent of the earthquake is not firm, at least in the state, as the population was composed largely of colonial settlers who had left the east coast. The 1663 earthquake felled chimneys, oscillated houses, and threw pewter from shelves in the Massachusetts Bay area.^[2]

Geography

Reports of the 1940 earthquake extended as far north as Montreal and Quebec in Canada, and included Maine, New York, New Jersey, Pennsylvania, northeastern Delaware, Massachusetts, Vermont and Rhode Island.^[3] The epicenter was next to the Ossipee Mountains, near the town of Ossipee, New Hampshire. These mountains are the remains of an ancient volcanic ring dike.^[4] A similar ring dike can be seen in southern New Hampshire at Pawtuckaway State Park.

Damage

With a Richter magnitude of 5.5 and a Mercalli intensity of VII, the earthquake spawned waves of minor damage around its epicenter. There were reports of fractured pipes, walls, and furniture, as well as "fallen plaster" near the epicenter.^[3] The number of chimneys damaged totaled 20, in addition to fallen ones. The earthquake caused damage to wells, turning the water brown^[3] and displayed strength by movement, causing five monuments to shift from their original position at a cemetery, and moving one old house in the village of Wonalancet roughly 12 inches (30 cm). The earthquake additionally shifted objects as heavy as stoves. Aftershocks of the earthquake occurred over the next several months.^[3]

References

1 2 3 4 5 6 Stover, C. W.; Coffman, J. L. (1993), Seismicity of the United States, 1568–1989 (Revised), U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, p. 302
↑ "New Hampshire - Earthquake History". United States Geological Survey. October 21, 2009. Archived from the original on December 15, 2009. Retrieved December 24, 2009.
1 2 3 4 "Historic Earthquakes". United States Geological Survey. October 21, 2009. Retrieved December 20, 2009.
↑ Hall, Anthony, Igneous Petrology, Longman, 1987 p.75–76 ISBN 0-582-30174-2

Sources

Billings, M. P. (1942), "Geology of the Central Area of the Ossipee Mountains, New Hampshire, earthquakes", Bulletin of the Seismological Society of America, Seismological Society of America, 32 (2): 83–92
Devlin, J. J.; Langguth, L. C.; Arringdale, R. L. (1942), "Macroseismic study of the New Hampshire earthquakes of December 1940", Bulletin of the Seismological Society of America, Seismological Society of America, 32 (2): 67–73
Don Leet, L.; Linehan D. (1942), "Instrumental study of the New Hampshire earthquakes of December, 1940", Bulletin of the Seismological Society of America, Seismological Society of America, 32 (2): 75–82

External links

Quakes in east bigger puzzle than those on west coast – The New York Times

← Earthquakes in 1940 →
El Centro (6.9, May 18) Vrancea (7.7, Nov 10) †‡ New Hampshire (5.3 & 5.6, Dec 20 & Dec 24)
† indicates earthquake resulting in at least 30 deaths ‡ indicates the deadliest earthquake of the year

Earthquakes in the United States
Historical	1638 New Hampshire 1663 Charlevoix 1700 Cascadia 1755 Cape Ann 1811–12 New Madrid 1838 San Andreas 1857 Fort Tejon 1865 Memphis 1867 Manhattan, Kansas 1868 Hawaii 1868 Hayward 1872 Lone Pine 1872 North Cascades 1886 Charleston 1887 Sonora 1892 Laguna Salada 1892 Vacaville–Winters 1898 Mare Island
20th-century	1906 San Francisco 1906 Aleutian Islands 1909 Wabash River 1915 Pleasant Valley 1916 Irondale 1918 San Jacinto 1925 Santa Barbara 1931 Valentine 1932 Eureka 1933 Long Beach 1935 Helena 1940 El Centro 1940 New Hampshire 1944 Cornwall–Massena 1946 Aleutian Islands 1947 Wisconsin 1948 Desert Hot Springs 1949 Olympia 1952 Kern County 1957 Andreanof Islands 1957 San Francisco 1959 Hebgen Lake 1964 Alaska 1965 Rat Islands 1965 Puget Sound 1968 Illinois 1969 Santa Rosa 1971 San Fernando 1973 Point Mugu 1975 Near Islands 1975 Morris 1975 Hawaii 1979 Coyote Lake 1979 Imperial Valley 1980 Eureka 1983 Coalinga 1983 Borah Peak 1984 Morgan Hill 1986 North Palm Springs 1986 Chalfant Valley 1987 Whittier Narrows 1989 Loma Prieta 1990 Upland 1991 Sierra Madre 1992 Cape Mendocino 1992 Landers 1992 Big Bear 1993 Scotts Mills 1993 Klamath Falls 1994 Northridge 1995 Marathon 1996 Duvall 1998 Pymatuning 1999 Hector Mine 2000 Yountville
21st-century	2001 Nisqually 2002 Denali 2003 Alabama 2003 San Simeon 2006 Gulf of Mexico 2006 Kiholo Bay 2007 Alum Rock 2008 Illinois 2008 Chino Hills 2010 Eureka 2010 Illinois 2010 Baja California 2010 Indiana 2011 Colorado 2011 Virginia 2011 Oklahoma 2014 Aleutian Islands 2014 Southeast Alaska 2014 South Napa 2016 Oklahoma 2016 Hawthorne
Swarms	2001 Enola 2008 Reno 2010–11 Guy-Greenbrier 2012 Brawley 2009–17 Oklahoma

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