Home International RMS : commentary on Oklahoma Mw5.6 earthquake

RMS : commentary on Oklahoma Mw5.6 earthquake

0 0

On Saturday, November 5, (22:53 local time) a moderate moment magnitude Mw5.6 earthquake occurred in central Oklahoma. The USGS have reported a depth of 3.1 miles and an epicentral location in southeast Lincoln County, Oklahoma, approximately 21 miles north-northeast of Shawnee (in Pottawatomie County),Oklahoma; 44 miles east-northeast of that state capital Oklahoma City. This earthquake was felt as far away as Cleveland, Ohio and Coraopolis, Pennsylvania, located approximately 915 miles and 965 miles northeast of the epicenter respectively.

According to the Oklahoma Geological Survey (OGS), a foreshock of magnitude Mw4.7 occurred earlier on Saturday,  November 5, at 07:12 UTC (02:12 local time). It is believed that this earthquake occurred on the Wilzetta fault, otherwise known as the Seminole uplift.

According to the USGS ShakeMap, the maximum intensity ground shaking in the vicinity of the epicenter was VIII (‘severe‘) on the Modified Mercalli Intensity (MMI) scale. This level of ground shaking could be expected to cause moderate/heavy damage to resistant structures and heavy damage to vulnerable structures, however according to the USGS PAGER, only 3,000 people were exposed to this level of shaking. Over 2.6 million people were exposed to intensity V or stronger shaking, where damage to structures can begin to occur. The city of Prague (population 2,000) experienced intensity VIII shaking, with the city of Shawnee (population 26,000) experienced intensity VI. The larger cities of Oklahoma City and Tulsa (population 533,000 and 393,000 respectively) experienced intensity V shaking.

Information from Lincoln County Emergency Management (as of 09:00UTC Monday, November 7) is that 12 homes, in the Prague area (in the southeast of the state) have sustained significant damage. Some structural damage, including a roof collapse and a damaged ventilation system has been reported to a municipal building and three sections of U.S. Route 62 have buckled.

No fatalities have been reported as a result of the earthquake. Oklahoma State Department of Health has reported two instances of minor injuries.

The Mw5.6 earthquake is the largest earthquake to occur in the state of Oklahoma, according to the OGS. The previous record was set in 1952 when a magnitude 5.5 earthquake occurred in El Reno City. Oklahoma appears to have had a phase of heightened seismic activity since 2009 in terms of the frequency of earthquakes recorded in the state, as indicated by the OGS, however the intensity of these tremors is in line with what is deemed normal seismic activity.

RMS will continue to monitor the situation and update accordingly.

Source : RMS Press Release