Friday, March 23, 2012

Shake, Rattle, and Roll

     We learned an awful lot - as the general public - about earthquakes the last ten years or so.  Earthquakes happen all the damn time, but when giant, violent earthquakes and their associated tsunamis ripped apart Indonesia and Japan, the worldwide media rounded up some science correspondents and experts and taught us a lot about how the earth works when it shakes.  One of the neat things that they taught us was just how scientists - resplendent in their lab coats - determine where the epicenter of an earthquake lies.  See, the funny thing about earthquakes is that they actually cause rippled in the ground, seabed, Main St, your floorboards, etc, but these ripples generally travel at a constant rate.  So, what these scientists do is look at the results of seismographs all around the world, the more the better, to see how fast the waves were traveling and from what direction they came.  Then they bust out their TI-83's to figure out where all the directions meet and BOOM! (pardon the pun) that is where the epicenter is.
     The important part of this Bill Nye the Science Guy moment is that the seismographs that these scientists use can detect earthquakes from thousands and thousands of miles away.  Thousands of miles away.  The recent earthquake in Japan was picked up by seismographs in Hawai'i and California and Russia and the African Rift Valley.  Look at a map and see where those places are in relation to the Tokyo Dome.  And these seismographs are super sensitive.  So I am wondering why no one seemed to be able to pick up the earthquakes that were happening under Clintonville, Wisconsin last week.

This did not happen in Clintonville
       I don't know if you have been following what has been going on in the relatively sleepy farming and manufacturing community of about 4500 in central Wisconsin, but I will go ahead and lay it out for you.  A couple of days ago, calls started coming in to the friendly 911 operators about strange sounds and vibrations centered on a six-square block area on the northeast side of Clintonville.  Some of the early calls was recently released to the media and the caller described a series of loud bangs that sounded almost like a car door slamming or fireworks going off, but he was unable to pinpoint the direction from where it was coming.  Other calls descibed a shaking.  City officials did exactly what city officials should have done.  They sent their sewer and water guys out to check the system.  They called up the natural gas folks and they came out and checked their system.  They had a big public meeting at the local high school a couple of times to keep people informed.  After three or four pretty much sleepless nights the city went out and hired an engineering firm to place instruments in the ground to try and pinpoint where the bangs were coming from.
     Enter the United States Geological Survey, a day late and a dollar short.  They called up the Clintonville City officials and confirmed to them that the city had experienced a series of very small earthquakes, and they confirmed the one that they bothered to measure was a 1.5 on the Richter scale.  So it turns out that all of those sensitive siesmographs DID pick up whatever was shaking, rattling, and rolling approximately 3.1 miles beneath Clintonville, Wisconsin.
US earthquakes during the past week, as of 9:04 AM CDT, Friday, March 23, 2012.  Most of the earthquakes depicted on this map would not have been strong enough to be felt by human beings.
        Now...1.5 magnitude earthquakes happen all the time.  In the last week there have been earthquakes roughly the same size in South Carolina, Virginia, West Virginia, Tennessee, New Mexico, and Montana.  And there have been dozens of the same size in California and Alaksa.  And nobody bats an eyelash.  Human people generally don't have sensitive enough natural equipment to pick that size earthquake up, and most buildings don't even rattle.  So why all the freaking out in Clintonville.  What is with that business?  The lab coats at the USGS - now that they are paying attention to the situation - had a handy explanation for that too.  They said that there is a lot of solid, hard granite under the fertile soils of the town.  You might know it as bedrock.  Because of the nature of the granite, it amplified the shaking and motion and sound of the earthquake into something that all those people could hear and feel.  As to why it was only in a small area, no one knows.  But at least the town has some releif.  And it got its fifteen minutes of fame in the national spotlight.  Maybe that's the way to get the USGS to notice your situation...


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