California quake 'a teachable moment' for those living on New Madrid fault

KENNETT, Mo. -- Marian and John McDonald spend part of the year in Kennett and the other part in the northern California town of Sebastopol.

The 6.0 Napa earthquake that hit Aug. 24, just 40 miles east of the McDonalds' home, was "quite a wake-up call," said Marian McDonald, who called this "a teachable moment" for people living near the New Madrid fault line.

It's estimated the Napa quake caused $1 billion in damage to California's wine country and injured 170 people. While the McDonalds experienced no property damage, Marian McDonald said she and her husband were reminded to be prepared, because one never knows when a disaster will strike.

"You always expect [it] to hit over there, but it's really bad when it hits here," she said.

In July, the U.S. Geological Survey updated its national seismic hazard maps for the first time since 2008. The maps are used for building codes and insurance purposes, and they calculate just how much shaking an area is likely to experience. While new, high-risk areas were added to the maps, states along the New Madrid fault, including Missouri, Arkansas, Tennessee, Illinois and Kentucky, remain among those at highest risk.

In the past two weeks, a series of microearthquakes have rolled through western Tennessee and along Reelfoot Lake in Kentucky. Micro earthquakes register 2.0 or less on the Richter scale. In addition, a 2.0 tremor occurred in Caruthersville, Missouri, on Tuesday and a 2.3 happened in New Madrid, Missouri, on Aug. 26.

State Emergency Management Agency officials said those events are not necessarily a reason for heightened concern, because the region is known for small tremors that occur regularly.

Kennett Public Safety director John Mallott, who is also the city's emergency management director, said the fine alluvial soil in the region acts as a sponge, absorbing the level of shaking so much that people often don't feel it.

Mallott stressed, however, that residents should be prepared for a disaster, no matter its nature. Mallott is serving his second term on the Missouri Seismic Safety Commission, having been appointed by Gov. Jay Nixon. The commission is part of SEMA within the Missouri Department of Public Safety.

Top on Mallott's mind is how to get state and federal officials to view the six to seven counties of the Bootheel and Southeast Missouri as a top priority if a major earthquake occurs.

"Things don't stop at Cape," Mallott said. "You've still got 110 miles of Missouri left [below there]."

He said along Interstate 55 if a major quake damaged or dropped bridges over the Black, St. Francis and Castor rivers and the Diversion Channel south of Cape Girardeau, "you're on an island." What Mallott would like is for Highway 25 to be designated as an emergency corridor because it has an overpass only at Malden, Missouri, and a creek bridge north of Holcomb, Missouri -- structures that can be quickly repaired or detoured if they are damaged.

He said parts of the highway already are considered emergency routes, but he would like to see the full length designated because it would be the only way of getting emergency goods into what he called "the deep Bootheel" if Interstate 55 was rendered impassable. Mallott said the Malden Air Base also could be used as an emergency staging area.

In any emergency preparations, Mallott cautioned that food, water and shelter should be of top concern in the first 72 to 96 hours after a disaster.

Opinion is divided as to how much threat the New Madrid fault represents. Some scientists and seismologists feel the fault may go dormant because the last 6.0 or greater quake was in 1895 near Charleston, Missouri.

However, Dr. David Stewart, a former USGS engineer and director of the Center for Earthquake Studies at Southeast Missouri State University, said the average time span between quakes of 6.0 or greater magnitude is every 100 years. That would put the New Madrid fault overdue for a sizable tremor. Stewart is considered one of the foremost authorities on the New Madrid fault zone and has written several books on the subject.

The USGS has stated the frequency of earthquakes in the central and eastern U.S. has quadrupled to an average of 100 a year, as recently as the 2011-2013 period. That's up from only 20 per year during the 30 years leading to 2000.

While most of those quakes were considered minor, 2014 USGS research indicates some of that activity was triggered by wastewater injection after conventional oil drilling, and other ground disruptions related to oil fracking.