Many buildings in Charleston, South Carolina, were damaged or destroyed by the large earthquake that occurred August 31, 1886.
U.S. Department of the Interior / U.S. Geological Survey
Earthquakes
by Kaye M. Shedlock and
Louis C. Pakiser
For sale by the U.S. Government Printing Office
Superintendent of Documents
Mail Stop: SSOP, Washington, DC 20402-9328
One of the most frightening anddestructive phenomena of natureis a severe earthquake and its terribleaftereffects. An earthquake is a suddenmovement of the Earth, caused bythe abrupt release of strain that has accumulatedover a long time. For hundredsof millions of years, the forces of platetectonics have shaped the Earth as thehuge plates that form the Earth’s surfaceslowly move over, under, and past eachother. Sometimes the movement is gradual.At other times, the plates are lockedtogether, unable to release the accumulatingenergy. When the accumulatedenergy grows strong enough, the platesbreak free. If the earthquake occurs ina populated area, it may cause manydeaths and injuries and extensive propertydamage.
Today we are challenging theassumption that earthquakes must presentan uncontrollable and unpredictablehazard to life and property. Scientistshave begun to estimate the locations andlikelihoods of future damaging earthquakes.Sites of greatest hazard are beingidentified, and definite progress is beingmade in designing structures that willwithstand the effects of earthquakes.
USGS scientist uses portable seismic recording equipment near Mount St. Helens, Washington.
Earthquakes in History
The scientific study of earthquakesis comparatively new. Until the18th century, few factual descriptionsof earthquakes were recorded, andthe natural cause of earthquakes was littleunderstood. Those who did look fornatural causes often reached conclusionsthat seem fanciful today; one populartheory was that earthquakes were causedby air rushing out of caverns deep in theEarth’s interior.
The earliest earthquake for whichwe have descriptive informationoccurred in China in 1177 B.C. TheChinese earthquake catalog describesseveral dozen large earthquakes in Chinaduring the next few thousand years.Earthquakes in Europe are mentioned asearly as 580 B.C., but the earliest forwhich we have some descriptive informationoccurred in the mid-16th century.The earliest known earthquakes in theAmericas were in Mexico in the late14th century and in Peru in 1471, butdescriptions of the effects were not welldocumented. By the 17th century, descriptionsof the effects of earthquakeswere being published around theworld—although these accounts wereoften exaggerated or distorted.
The most widely felt earthquakes inthe recorded history of North Americawere a series that occurred in 1811-12near New Madrid, Mo. A great earthquake,whose magnitude is estimated tobe about 8, occurred on the morning ofDecember 16, 1811. Another great earthquakeoccurred on January 23, 1812, anda third, the strongest yet, on February 7,