Midwest Earthquake Hazard Downplayed 96
swellconvivialguy writes "Next year marks the bicentennial of the 1811-12 New Madrid earthquakes, with earthquake drills and disaster tourism events planned across the Midwest, including the Great Central US ShakeOut. But despite the fact that Earthquake Hazard Maps equate the New Madrid seismic zone with California, geologist Seth Stein says new science (especially GPS data) tells us that the hazard has been significantly overestimated, and that we should not spend billions on earthquake preparations in the Midwest."
Re:So Confused on the GPS Data and Logic (Score:5, Informative)
When we look at faults around the world, we see them storing up that energy. So when we first put markers in the ground and measured the position of the Midwestern fault lines we were surprised that we didn’t see any motion at New Madrid. We concluded that there’s no sign that a big earthquake is on the way.
I'm not a geologist so I'm very confused, if something is 'storing up energy' how does moving around equate to that? I mean, if the moving of the ground in violent ways is the releasing of that 'stored energy' then how is small movements indications that it's storing up energy? I would assume that the worse earthquake areas are those when there's a lot of movement going on deep underground but nothing on the surface releasing that energy until a very devastating movement.
Your answer is in the previous paragraph in the article:
"It lets us see the ground storing up that energy and deforming ".
There's Nothing to See Here! (Score:1, Informative)
Some sections of the Mississippi River appeared to run backward for a short time. Sand blows were common throughout the area, and can still be seen from the air in cultivated fields. The shockwaves propagated efficiently through midwestern bedrock. Residents as far away as Pittsburgh and Norfolk were awakened by intense shaking. Church bells were reported to ring as far as Boston, Massachusetts and York, Ontario (now Toronto), and sidewalks were reported to have been cracked and broken in Washington, D.C." (http://en.wikipedia.org/wiki/1812_New_Madrid_earthquake [wikipedia.org])
"...chimneys were toppled and log cabins were thrown down as far distant as Cincinnati, Ohio, St. Louis, Missouri, and in many places in Kentucky, Missouri, and Tennessee." (http://earthquake.usgs.gov/earthquakes/states/events/1811-1812.php [usgs.gov])
Don't worry folks! There's nothing to worry about! It's only flyover country anyway...
Re:So Confused on the GPS Data and Logic (Score:3, Informative)
the difference between and earthquake, and not is how QUICKLY the energy is released.
think of it this way.. take X amount of energy and bend a piece of wood over 100 years. take that same amount of energy and apply it in 10 seconds. Over a hundred years, you'll end up with a bent piece of wood.. in 10 seconds, you get a snapped piece of wood. tectonic movement is slow bending, earthquakes are the snap. you don't notice a shift of an inch over 20 years, but in an earthquake, it's shifting FEET in SECONDS.. slow movement (release of energy) is not nearly as devastating or violent as a quick release.
the Hayward fault runs right though CAL Berkeley Stadium. every so often, over the course of years, there's a measurable movement (one side vs. the other)..
see the pics. before you click on the link.. all that movement happened over ~hundred years (the stadium was built in 1922-23)
http://seismo.berkeley.edu/hayward/ucb_campus.html [berkeley.edu]
if there was a major quake on that fault.. row 5 on one side of the fault would match row 6 on the other.
we all know the Bay Area is a hotbed of earthquake activitity because of sublte signs like the last 2 pics on the link.. apparently, there was no such "creep" on the Midwestern Fault - so they weren't expecting an earthquake.