The New Madrid Fault is very scary!
I’m sure you have all heard about the Illinois earthquake that happened this morning. I’ve been noticing that the news hasn’t spent much time on it. At first they were reporting that it was along the New Madrid Fault. Then they started saying, ‘NAW, its not a big deal, don’t worry about it,’ and downplaying that the New Madrid Fault might have had anything to do with it.
That’s because we are little commoners in Middle America who might get upset if we hear something scary and start clinging to our Bibles and guns because we have nothing else to cling to. They have to protect us from that sort of thing, ya know!
I have found out that the reason the New Madrid Fault if being downplayed is that it is a very scary fault. I had no idea. Y’all are probably a little like me. I don’t think of earthquakes in relation to Middle America. I think earthquakes are the curse of California because we all know how California is (wink, wink). I’m just kidding. Some of my best friends are in California so I know there ARE a few good people there. But that IS where we think of earthquakes happening so we don’t really worry about them much. Its THEIR problem, not ours.
As it turns out, the New Madrid Fault is actually more dangerous than the San Andreas Fault. Who knew? A friend of mine has explained the whole thing and she’s something of an expert on it.
Here are some facts that may or may not have you clinging to your Bibles and guns by the end of this post.
There are different seismic zones. The San Andreas fault is a fault because it is a place where two tectonic plates slide against each other. An earthquake occurs when the two tectonic plates get stuck against each other and then unstuck. The ‘unsticking’ part is when you have the earthquake. Then there’s the New Madrid Fault. Its set up differently than the San Andreas fault. It is more like a series of scars and mini-faults rather than two big ol’ faults that are rubbing against each other.
About One hundred gazillion years ago the North American plate tried to break apart two different times. Those periods of activity led to rifts and scarring of the plate. There is a main rift which is roughly along the Mississippi River. Its as active as a plate or plate fault would be expected to be. Along the rifts a lot of sediment piles up. When things start moving around in this seismic zone, the sediment energy from the movement and ripples along the fault. Its similar to the way water moves when it ripples only this is land. Or you can imagine the vibrations from a big gong that vibrates … and vibrates … and vibrates.
This vibrating along multiple rifts means that it doesn’t produce a big snap followed by tremors like the San Andreas fault does. Instead, the New Madrid fault produces a more rolling quake that has the possibility of lasting longer and doing damage further away from the epicenter. The Great San Francisco quake was an 8.0 earthquake on the Richter scale. It was felt from Oregon to Los Angeles. It was on the San Andreas Fault. The last quake in the main fault of The New Madrid Fault was in 1812. It was a 7.9 on the Richter scale and was felt from New Orleans, houses were destroyed in St. Louis (150 miles away) and sidewalks broke up in Washington D.C.
When we think of earthquakes we think they happen on the San Andreas fault. There are a lot there and when they happen they are big. In Middle America we rarely think of earthquakes even though there are thousands. Its just that they usually happen in the smaller faults and not in the main part of the New Madrid Fault. They are usually too small to feel or if we do feel it we think its a fluke of some kind and go on about our business.
A larger quake, like what happened today apparently is of some concern to seismologists as it indicates that the main New Madrid Fault might have been involved in the quake and that is not a good thing. A quake in the main fault of the New Madrid Fault would be like nothing we’ve seen since …. since 1812 obviously. For those of you not real sharp on history, that was before we had a lot of big cities, or even towns, between New Orleans and Chicago. We are a lot more densely populated now and there’s a lot more buildings along that fault.
In recent years scientists have been theorizing that the New Madrid Fault was pretty much dead or dying and was no longer the threat it once was. Todays earthquake shook that theory up a bit. It turns out that its probably not quite as dormant as the seismologist wanted everyone to think – or hoped it was. I have this image of seismologist running around like little mice testing the ground and doing whatever it is they do to try to figure out where this quake was located and praying every step of the way that it wasn’t in the main New Madrid Fault.
That is why the news is downplaying that possibility to the public because its really a pretty frightening possibility and most of us prefer blissful ignorance. I know I do as a general rule.
Have a great weekend with THAT in mind!!