Living at the edge of the New Madrid fault zone (NMF) means the threat of a damaging earthquake for central Arkansas is nearer than many people realize, David Johnson of the U.S. Geological Survey office at Little Rock said Thursday. Arkansas is in the most seismically active area east of the Rocky Mountains, and predictions are that the area has a 40 percent likelihood of feeling the power of a magnitude 6 earthquake in the New Madrid Fault by 2040, he said.

Johnson was one of the speakers for an earthquake preparedness drill conducted by the Lonoke County Office of Emergency Services director Kathy Zasimovich. State emergency services officials and first responders from throughout central Arkansas attended the drill, part of local observance of the Great Central U.S. ShakeOut, a regional earthquake preparedness drill, Zasimovich said before the session.

Information from the Center for Earthquake Research and Information, at Memphis, shows there were 22 earthquakes, ranging from magnitude .8 to 2.9, registered in the NMZ between Jan. 1 and Feb. 10, 2013. Generally, earthquakes less than 4.0 are not felt.

Earthquake magnitude is an exponential scale — the Great New Madrid Earthquake, actually three events: Dec. 16, 1811, Magnitude 7.7; Jan. 23, 1812, 7.5, and Feb. 7, 1812, 7.7, were felt in Boston, Mass.

To begin the drill, Zasimovich said that at 9:30 a.m. a magnitude 6.0 earthquake had been registered north of Marked Tree, and that Lonoke County felt the earthquake as a mild event incurring some damage.

The Lonoke County Emergency Operations Center was activated at 9:45 a.m. and began the emergency recall of elected officials and EOC staff. EOC was declared operational at 10 a.m.

Zasimovich said the NMF extends 120 miles south of Charleston, Mo., and Cairo, Ill., through the namesake New Madrid, Mo., follows Interstate 55 to Blytheville and then to Marked Tree.

Johnson said that states directly affected by the NMZ are Arkansas, Missouri, Indiana, Illinois, Tennessee, Alabama, Mississippi and Kentucky.

Lonoke County’s challenge is that it shares varying physiological “provinces,” each with specific dangers according to the soils of each area, Johnson said. Not only is there the danger of ground motion, but a condition called “liquefaction” when the soil acts as a liquid.

It is predicted that there is up to a 40 percent probability of a 6.0 earthquake on the NMF by 2040, severe enough to produce liquefaction, Johnson said.

The fault is active, averaging more than 200 measured events per year, 1.0 or more on the Richter scale. Every 18 months the fault releases a shock of 4.0 or more, capable of local minor damage. A 4.3 earthquake happened Thanksgiving Eve 1996 which was felt by citizens in the states of Missouri, Arkansas, Tennessee and Kentucky, Illinois and Mississippi.

In the drill, County Judge Doug Erwin declared Lonoke County a disaster area, the proclamation was certified by County Clerk Larry Clarke, setting in motion calls for aid and services from other areas.

“If there is a resource that Lonoke County does not have, or if any of our Mutual Aid Partners can supply, we will coordinate with Arkansas Department of Emergency Management to get it,” Zasimovich said.

Special response teams on standby in the county include the Lonoke County Swift Water Rescue Team, led by John Huett; Arkansas Task Force 1 Urban Search and Rescue (USAR) and the Pulaski County Hazardous Material Team, both led by Andy Traffenstadt, Zasimovich said.

Traffenstadt said the term “Urban” could be misleading to some. “We aren’t just about cities, urban areas. We deal with damaged construction, such as concrete,” he said.

Communciations networks were established under disaster communications director Hubert Chapman, from South Bend Volunteer Fire Department; media contacts were established under Lt. Jim Kulesa, sheriff’s office public information officer; and duties assigned to various agencies and organizations.

Agencies organized to aid recovery include: the Arkansas Army National Guard Medical Unit; American Red Cross; Lions Club International Regional Disaster Response; Baptist US Disaster Response; Presbyterian Disaster Response; and locally such as Hopes Closet and Lonoke County DHS.

The drill ended after tasks such as responding to road damage and rescuing victims trapped in a collapsed building were completed.

A debriefing of the drill will be held Tuesday.