Avian Flu Diary: 5.6 Mag Quake Rattles Oklahoma

# 5944

While not well known as a hotbed for seismic activity, the state of Oklahoma has seen an unusual number of earthquakes over the past couple of years. In 2010, the Oklahoma Geological Survey Observatory recorded 1,047 earthquakes, of which 103 were strong enough to be felt by the public.

The largest of these was a 4.7 magnitude earthquake which occurred near Norman, Oklahoma on October 13th, but a number of smaller quakes also occurred east of Oklahoma City (near Jones), with the strongest topping out at magnitude 4.0.

Overnight a series of earthquakes – with the largest coming in at magnitude 5.6 – have been reported east of Oklahoma City.

This from the Oklahoma Geological Survey:

Preliminary Earthquake Report, November 5, 2011

Contacts: Austin Holland or Amie Gibson, Oklahoma Geological Survey, (Email Us)

On November 5, 2011 at 2:12 AM CDT (07:12:45.4 UTC) an magnitude 4.7 earthquake occurred in Lincoln County, Oklahoma. This turned out to be a foreshock to a much larger earthquake. The mainshock occurred at 10:53 PM CDT (11-6 03:53:10 UTC). The earthquakes occurred about 6 miles northwest of Prague and 5.2 miles southeast of Sparks. These earthquakes occurred very close to where a magnitude 4.3 earthquake occurred on February 27, 2010. From the location of the earthquake and the focal mechanism it is most likely that this earthquake occurred on the Wilzetta fault also known as the Seminole uplift. We are currently working to locate the numerous aftershocks will continue to update information as we can.

USGS Event Page

We will be updating this page as we get more information so please check back.

There are reports of mostly minor damage in the region, including one roof collapse, and buckling of section of U.S. Route 62. At least one injury has been reported (see CNN report).

While this is the largest earthquake recorded in modern history in the state of Oklahoma, the geological record shows evidence of a much larger quake (6.5-7.0) about 1300 years ago in the south-western part of the state.

The USGS has received more than 50,000 responses on their `Did You Feel it?’ website, and has generated the following shake map showing where the effects of this quake were felt.

As you can see, people as far away as Indiana reported feeling the temblor.

Last night’s quake, along with the 5.8 quake that struck Virginia in August of this year (see USGS Statement On The Virginia Earthquake) are reminders that you don’t have to live in California, the Pacific Northwest, or Alaska to be impacted by an earthquake.

While large earthquakes in the eastern half of the country are relatively uncommon, they do happen. Charleston, S.C. was devastated by a 7.3 magnitude quake in 1886.

USGS map

As you can see by the map above, most of the United States is seismically active – with Alaska, Hawaii, the west coast, and the mid-west seeing the most – and strongest, quakes.

Few places, however, can claim to be completely immune to quakes.

A couple of months ago, during the 2011 National Preparedness Month campaign, I wrote at length about earthquake preparedness (see NPM11: Are You Earthquake Prepared?). There you’ll find many resources, including the The L. A. County Emergency Survival Guide.

And to become better prepared as an individual, family, business owner, or community to deal with all types of disasters, I would invite you to visit the following preparedness sites.