Fault

Part 22

New Madrid Fault Right Beneath Our Feet

By: Carrie DeCastro

In the wake of today's events in Missouri we are rereleasing an opinion piece written by author Carrie DeCastro earlier last year.

ST. LOUIS (AP) – They say that when you get Mississippi mud between your toes, you never again stray far from the river. The banks of the mighty waterway twist through the heart of the Midwest like a vital vein. It connects north and south. Transportation, recreation and the creation of vocations are just some of the things it boasts on its resume. St. Louis' Gateway Arch towers above the water as a reminder of the struggles the frontier families faced, the first line of Americans stretching the boundaries.

The St. Louis of today is a home to almost three million people. It's a sprawling metropolis of red brick and racial division. It sits with its east side against the Mississippi and its west opens up into the state of Missouri. The oak and maple trees turns vibrant shades of orange and red in autumn and mosquitoes along the river in summer cause the shelves to run out of bug spray. The city has seventy-nine neighborhoods, sixty-six square miles of area and though some strides to restore the worn places have been made, it hasn't been enough.

In 1811, there were little more than sixteen hundred people living in St. Louis, which would not be incorporated until eleven years later. Centered around a Catholic church built out of logs, there were mainly individual homes in the city at the time. There were four main streets running north and south and they had French names. See, even though the United States could claim St. Louis as their own after the Louisiana Purchase, the population still held several French fur traders.

The early morning hours of December 16th, 1811, held the promise of Christmas only a couple weeks away and though the air was chilly, there wasn't any snow to coat the wood shingled roofs. Most people were asleep in their beds, knowing that with dawn would come the daily task of surviving yet another day on the dangerous frontier.

The Shawnee tribe was becoming more aggressive. Animals hunted the forest just as the settlers did and they would just as soon eat you as you would eat them. Disease was a constant worry. With all these hazards above ground, they did not imagine, could not imagine, that beneath their feet lay the most dangerous hazard of all. The New Madrid Fault Line.

Around two a.m. the ground began to shake with a thunderous noise. Reports describe the ground as moving like a wave, rolling in ripples as if God himself had dropped a marble from the sky. The weak construction of buildings meant that they were of no match for the quake, which reduced most towns to a pile of lumber. The few who owned chimneys, built either of stone or brick, saw that those were the first to come down.

During the earthquake of 1811, people panicked and ran into the streets.

Those who didn't, typically never made it out of their structures alive. The Mississippi, being already a busy transportation route, swallowed more souls that night than could ever be counted. Fissures opened up all over the earth, including under the water of the river, which kicked up so much soil that it actually reversed the direction of the Mississippi for three days. Sulfur spewed up into the air with dirt, sand and clay, causing a haze that stayed for weeks. The entire town of New Prairie sunk into the ground, as if they had built their structures on quicksand. Which, in a way, they did.

You see, the Midwest carries a danger beneath its soil that neither the west nor east coast have. Our ground is soft, sandy and saturated. Buildings stand on the principle that the grains of soil and sand stay in contact with each other, only allowing a small space for pores where water will flow between them. Imagine a pool full of people, standing shoulder to shoulder. Being so strongly united would tolerate another person to walk across them without getting wet. However, this only works as far as the people in the water stay in place. The water can flow easily between them, finding its path in even the tight spaces. If chaos were to erupt and the people treat the pool like a mosh pit, the water would be forced to find other avenues of escape. For a water molecule cannot be destroyed, and it will always find a way out.

The stress caused in a quake turns the grains of soil into the panicking people in the pool, forcing the water under pressure. The water then breaks the contact individual grains have with each other, severing chemical bonds that hold our buildings upright. Without other soil grains to cling to they become aimless, and start to flow like water. We call this process liquefaction. When this occurs under structures, the results are devastating. This is how the frontier town of New Prairie was lost.

The damage radius of the New Madrid earthquakes stretched over 270,000 square miles. It shook the church bells in Boston and made the sidewalks split in the nation's capital. Seismologists retroactively declared the earthquake as an 8.2 on the Richter Scale.

Let me take a moment to clarify the meanings behind Richter Scale readings. For comparison I'll equate the ratings to the force various explosive devices create when detonated.

Imagine yourself on some bright sunny day, perhaps its warm, perhaps its cold, in the middle of a city. Buildings constructed out of mostly red brick and entirely of the last century, surround you. Now imagine that approximately five to fifteen feet beneath your soles, these devices are buried under the earth just biding time before something sets them off.

Anything less than 2.0 is a micro-quake and those are happening almost constantly under the surface. These really are like a grenade or single stick of dynamite, which isn't felt over a large area, but if you're right on top of it, it won't be comfortable.

If it registers between 2.1 and 3.9 than it is minor and may or may not be felt. Most of New Madrid's thousands of earthquakes fall into this range. It is believed that the frequent minor quakes we've had since the 1811-1812 series are actually still aftershocks. Two hundred years later and the earth is still trying to recover from those four explosive quakes.

Between 4.0 and 6.0 you are experiencing something like a fuel plant explosion. What is happening to the buildings around you?

Between 6.1 and 8.0, and you are detonating around six million tons of TNT. Are you still on your feet? Is it raining red brick?

An earthquake reading of 8.1 to 9.5 would be on par to the volcanic explosion seen at Krakatoa, which was stronger than the atomic bomb that destroyed Hiroshima. At this point, if you really were in a downtown city area, I would start praying.

The recent Tohoku Earthquake in Japan was a magnitude 9.0 and the 1960 quake in Chile was a 9.5. Nothing higher than that has ever been recorded, but seismologists believe that 10 and above would be like a meteor hitting earth. The devastation would be truly beyond measure.

Seismologists predict that the New Madrid Fault has a ninety percent chance of producing a 6.0 earthquake before the year 2040. It also predicts that we have a ten percent chance of that earthquake being an 8.0 or higher. I don't know about you, but I don't like those percentages.