Earthquake 101 seminar discusses New Madrid Seismic Zone

Wednesday, February 26, 2020

Drop. Cover. Hold on. This is what one should do in the event of an earthquake.

Unlike tornadoes or floods, they cannot be predicted, however, when one hits, depending on the intensity, it can catastrophically impact a community.

An earthquake seminar held at Three Rivers Community College campus and live streamed, covered history of earthquakes in Missouri, the risk of them and how to prepare for such an event.

Jeff Briggs with State Emergency Management Agency stated it is a “matter of time before a big one hits.” He discussed the massive earthquakes that occurred approximately 200 years ago in 1811 and 1812 caused by the New Madrid Seismic Zone.

“In 1811 and 1812, some of the largest earthquakes in U.S. history happened right here in this area. The damage was felt far and wide,” said Briggs as he referenced a map depicting a series of earthquakes measuring 7 to 7.5 in magnitude.

He explained on the scale of 1 to 10, anything over a 6 is big and over 7 is a “whopper.”

East of the Rocky Mountains, the New Madrid Seismic Zone is the largest active earthquake zone in the United States.

“This is an active seismic zone with more than 200 felt events per year. When you combine those two together, the experts tell us, that we know it’s only a matter of time before more big ones hit here. That tells us we need to be prepared for it,” said Briggs, stating it does not mean it will happen, as there is no way of predicting it; however, there is a significant risk with 25 to 40 percent chance of a M6 or larger in 50 years and a seven to 10 percent chance of a M7 or larger in 50 years.

The large earthquakes 200 years ago were felt far and wide and measured to exceed a magnitude of seven. They were felt as far away as the east coast, Canada and the Caribbean according to records including people’s journals and letters as well as newspaper articles. Briggs stated there is written evidence of people feeling the earthquakes in Washington, D.C., sidewalks cracking in Cleveland and church bells ringing in South Carolina. There are also writings from President James Madison to former President Thomas Jefferson, which included, “There was one felt here, this morning at five or six minutes after 4 o’clock. Rather stronger than any preceding one and lasted several minutes.”

There were not many records depicting what may have been felt west of the Mississippi River at this time, as there were not many English-speaking people in the region.

The intensity of the earthquakes caused the Mississippi River to run backwards for a period, which was caused by the land lifting and temporarily damming the river even causing some waterfalls to develop.

Even though the New Madrid fault line is centrally located in the boot hill of Missouri, its location does not mean the impact would not be felt for many miles.

“An earthquake here is not just felt in southeast Missouri. An earthquake here is felt throughout the region, even all the way to the east coast.”

He presented a map of the intensity of an earthquake felt in California versus Missouri including damage and shaking felt. He discussed the geology of the two regions and explained why it is more widespread in the Midwest.

“The west coast is mountainous, and rocks are broken up, so when it shakes, it is certainly felt locally or regionally but it is not as widespread versus here in the Midwest we have cooler, flatter more connected rock underneath. The earthquake waves unfortunately travel much more effectively with the kind of geology we have in the Midwest…Similar magnitude earthquakes, we are going to feel the shaking over about 10 times wider area,” said Briggs stating it is significant and makes it harder to plan for.

Earthquake shaking also tends to follow the rivers because of the loose sandy wet soil that is a conductor of earthquake waves. “If you live along a river, even if you are far away from the epicenter, you are more likely to feel the shaking and damage from an earthquake,” said Briggs.

He discussed liquefaction caused from earthquakes, how it makes things seem as they have turned to mush and how it could possibly put at risk old brick and masonry buildings like ones featured in downtown St. Louis. Largely populated areas to possibly be greatly impacted include St. Louis and Memphis, Tenn.

The estimated state impact would be 82,000 injuries and 3,500 fatalities as well as an estimated 2.5 million without power and one million without water with an estimated $300 billion in damage.

Briggs discussed measures to take to be two weeks ready and prepared including an emergency kit, water, and to secure the water heater and tall furniture. Securing the water heater could help provide a source of water during a disaster which could possibly provide more than 40 gallons of water for a family.

Other safety steps he discussed included if a person is driving to pull over and stay in the car, and stay away from poles, electrical lines, bridges or anything that could fall. In addition to take cover wherever one may be if one was to occur.

Surprisingly, the state of Alaska is a hot spot of activity for earthquakes with 5,000 occurring a year and in 2019 a magnitude of earthquake in Anchorage.

The evening included additional speakers, one from Ridgecrest, Calif. where substantial earthquakes happened in July 2019.

Stephanie Meeks, who is the emergency management for the hospital in Ridgecrest, discussed the importance of being prepared and having a community response plan in place. Some things to be prepared for include emergency personnel, media, geologists, arrival of dignitaries, housing of first responders, loiters, tourism and PTSD. Meeks stated loiters came from 400 miles to steal after the recent Ridgecrest earthquakes and tourists sought “seismic selfies.” Many who experienced the earthquake were very traumatized.

A panel, which included Thomas L. Pratt - Research Geophysicist, Central & Eastern U.S. Coordinator USGS Earthquake Hazards Program; Eric Fuchs - Emergency Response Coordinator Missouri Rural Water Association; Daryl Sorrell - General Manager M&A Electric Cooperative; Chris Englebrect - Assistant to the Chief Safety & Operations Officer Missouri Department of Transportation; Mayor Tyler Rinehart - Missouri National Guard; Angela L. Nelson - Director Division of Insurance Market Regulation Missouri Department of Commerce and Insurance; Ricky King - Public Safety Specialist Spire Energy and Robbie Myers - Director Butler County Emergency Management addressed additional topics of things that may be impacted by a massive earthquake.

Englebrect with MoDOT stated they run drills annually and expressed concerns of how resources would be brought in as well as evacuating people.

Rinehart discussed the response of the National Guard which would include approximately 10,000 soldiers and airmen showing up in 24 to 48 hours with designated task forces.

Nelson discussed information about the insurance market concerning earthquake insurance. In 2000, 60 percent of Missourians had earthquake coverage. However, there has been a drastic drop in those with the insurance and the cost of premiums and deductibles is rising. Lacking insurance would greatly impede recovery.

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