OK did ya know? Earthquakes

  1. Friday, March 24, 2006 16:26

Generalized geologic provinces of Oklahoma
larger view
You would think since Oklahoma belongs to the stable central plains of the U.S. it wouldn't have earthquakes, but yet Oklahoma is a seismically active region averaging between 50 and 100 earthquakes a year.

Earthquake History of Oklahoma

The first earthquake known to have centered in the State occurred in September 1918. A series of shocks at El Reno produced only minor effects; the strongest was intensity V on September 10. Objects were thrown from shelves. Other shocks occurred on the next day. On December 27, 1929, another tremor centered in the same area was felt in portions of central and western Oklahoma. Some plaster cracked and at least one chimney fell (intensity VI) at El Reno. In addition, clocks stopped, objects moved, and some reports indicated the walls and floors seemed to sway. In several cities, people rushed from their homes in alarm. The total felt area included about 20,000 square kilometers.

The magnitude 5.5 April 9, 1952, earthquake centered near El Reno affected most of Oklahoma and parts of Arkansas, Iowa, Kansas, Missouri, Nebraska, and Texas. Damage from the 10:30 a.m. CST earthquake was not extensive, but many people in the epicentral area were alarmed, some to near panic. Portions of chimneys fell in El Reno and Ponca City (intensity VII). Bricks loosened from a building wall and tile facing of commercial buildings bulged at Oklahoma City. Also, plate glass windows were shattered in the business district of El Reno. The total damage amounted to several thousand dollars. Aftershocks were felt on April 11, 15, and 16, July 16, and August 14; an earthquake that was felt (IV) at Holdenville and Wewoka on October 7 apparently was unrelated to the April 9th event. Homes and buildings shook and some persons were awakened (V) at El Reno from the April 16th shock, which occurred 5 minutes after midnight. Felt reports were also received from Kingfisher, Oklahoma City, Tulsa, and Union City.

More...* From USGA
The latest earthquake detected here in Oklahoma was on Wednesday, March 15, 2006, at 08:30:26 UTC (02:30:26 AM CST). It was located at 35.01N 96.25W which is 30 miles W of McAlester, 30 miles NE of Ada, and 45 miles ESE of Shawnee.

The Meers Fault and Restaurant

In May of 1985, the Oklahoma Geological Survey installed a seismograph in the The Meers Store & Restaurant at Meers, Oklahoma to monitor the Meers Fault. The Meers Store became "MEO - Meers Observatory" and has proven to be one of the most sensitive stations in the country.
What about a big one?

The next potentially large earthquake to happen near Oklahoma could come from the New Madrid Fault zone. In December 1811 and January 1812 the central Mississippi valley was struck by three of the most powerful earthquakes in U.S. History. Even today this area is one of the most active earthquakes zones east of the Rocky Mountains.
More on Oklahoma Earthquakes

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