The New Madrid Earthquakes

Reelfoot Rift Zone

The Reelfoot Rift Zone has its biggest concentration in parts of 5 states which are:  Northeast Arkansas, Southwest Illinois, Western Kentucky, Southeast Missouri, Western Tennessee; even extending into Northern Mississippi.

It is here where the famous series of earthquakes during the winter of 1811-1812 rang church bells as far away as Boston and damaged scaffolds at the capitol building in Washington, D.C.  One of these earthquakes even made the mighty Mississippi flow backwards for a few hours, causing the lake “Reelfoot” which got its name from the seismic zone that made it happen!

General Plate Tectonics

Most earthquakes in the United States occur in Alaska and California.  These states are associated with the North American and the Pacific Plate boundaries, along with Oregon and Washington.  At this boundary, the heavier crust of the Pacific Ocean goes underneath the lighter crust of the North American plate.  This causes tension and rocks underneath North America get crushed and melted, causing geologic structures such as mountains and volcanoes, which is exactly what is going on over there.  First, it was the Rocky Mountains.  As North America continued to push and expand westward, the Sierra Nevada Mountains and the Coast Ranges were formed.

On the other side of the North American Plate is the Atlantic Rift, in which the plate is moving away from the Eurasian Plate.  Likewise, the Eurasian Plate is moving further away from North America and going towards the Pacific Ocean to the East.  The rift between North America and the Eurasian plates has caused the crust to split open and magma from underneath to surface upward, creating the Mid-Atlantic Ridge which is an undersea Mountain range going north to south right at the center of the ocean.  It is this rift that fuels the volcanoes in Iceland.  Iceland is a part of that ridge that extends above sea level.  It would be fair to say that the Atlantic Ocean is getting wider as the Pacific is shrinking.

Neither the plate boundary of the West Coast of the US, nor the Atlantic Rift underneath that ocean has anything to do with what is taking place in the central part of the country, where there are no current plate boundaries.  Note the word “current.”  It is believed that at one time (a very long time ago—before the time all the continents were one, the Pangaea), the North American plate was ripping itself up in Southeast Missouri, hence the name “rift.”  This rift never fully completed, (it never ripped open the surface) so geologists today consider this rift zone a “failed” one.  Yet, it is so deep below the surface and the tear is significant enough to cause this area to be a great seismic risk-hazard zone.  All this means is simply, earthquakes do happen in the middle of the country, where there are no plate boundaries and because of that, a greater area may have significant damage than areas that are prone to earthquakes due to crustal boundaries (like the Pacific Coast).  Why is this?

Impacts of Mid-Continent Earthquakes

The map on this page compares the Northridge Earthquake that damaged Northwest Los Angeles in 1994 to an earthquake that occurred at Charleston, MO in 1895.  Even though the LA earthquake was stronger than the Mid-continent one, the area of damage is relatively much smaller.  Again, why is this?  Notice at the West Coast, earthquakes happen much more frequently there because of plate boundaries.  Therefore, the ground below the surface is cracked, always being recycled and comparatively “newer.”   Earthquakes in Missouri, on the other hand, happen with less frequency, the ground is not being continually recycled and is much more brittle, “older.”  This causes surface waves of an earthquake to move with better effectiveness; hence, an earthquake here in the center of the continent will affect a bigger amount of area as the above map shows.

 http://upload.wikimedia.org/wikipedia/en/c/cb/Charleston1895.gif

What does this mean for the future? 

There is at least a 90% chance that an earthquake similar or more potent than the ones during the early nineteenth century could occur here in the rift zone by 2050.  That doesn't really give us much time, really.  These earthquakes could indeed happen in the next 35 or 40 years, but then again, could happen tomorrow.  The 1811-1812 New Madrid Earthquakes didn't cause so much death and destruction, mainly because the immediate area was sparsely populated.  Now, we have quite a few major cities that will no doubt suffer extensive amount of damage, like Memphis or St. Louis.  Other cities that may be profoundly affected would be Nashville, Louisville, Little Rock.  Even Northwest Arkansas could receive an extensive amount of damage even though it is 350 miles away!  Something to think about!  Be prepared, because the government has done a bang up job so far, considering that fiasco called "Katrina!"  Well, maybe we have learned our lesson thus far.  The aftermath of Sandy was much smoother!

Global Climate Change Scenarios

I've been reflecting about the global climate scenarios--after all, I am going to college to get a Bachelors degree in Earth Science!  Last Spring, I took Environmental Geology at NWACC and we had discussed global climate change for about two weeks.  

There is a concern about crossing that tipping point, to where contents inside the "kettle" spills out.  At which point is such that there is no reversing the damage and we will just have to deal with the outcome?  Have we come to that point?  I'm not sure there is anyone who knows exactly where and when that point is...  (we may have already reached that point, in which case, what we need to focus in on is damage control, though it doesn't seem likely that we are there yet.)

Furthermore, what complicates the issue is that we KNOW human activity has some role to play in global climate change.  How much our activity affects the climate is anyone's guess because there are other non-human factors that contribute (like volcanoes, especially the super variety that releases an awful amount of carbon, sulfer and methane into our atmosphere).  Plate tectonics has its role as well, when one recognizes that the continents are constantly moving about, reshaping and resizing our oceans, which in turn affects global climate.  We also have what are called "carbon sinks," which is a phenomenon (like plankton) that absorbs carbon dioxide, keeping it from being trapped in our atmosphere.  We know much about these sinks, who and what they are, but there are a few unknown ones out there. We know this because there is still quite a bit of carbon dioxide that is left unaccounted for. 

Another thing to consider is  that greenhouse gasses (GHG) are not necessarily a bad thing in of themselves.  Water Vapor is our biggest GHG.  Carbon dioxide is another culprit.  So is methane.  Without these gasses, life on earth would be very difficult, if not impossible.  GHG traps heat which gives Earth a blanket effect, keeping us from plunging into another ice age.  Otherwise, this planet would be really really cold.  The problem is, how much is too much? How hot do we need it to go?

Finally, to call it "global warming" is right to a certain extent.  We do know that overall the Earth will have warmer temperatures and drier conditions, though in some local areas, there will be more flooding (coastal areas) AND in others, such as Great Britian and Ireland, they could see another ice age, in spite of the trends.  Both of these scenarios defy "global warming" because temps are getting colder, not warmer.  There is a reason why both of these cases seem likely.  It is because with warmer temperatures, the glaciers will continue to melt, raising the sea levels (which is why coastal areas will be flooded out) and with this rise in the sea level, the warm current that flows off the Atlantic, the "Gulf Stream" will be buried underneath the sea and will no longer be able to give the moderate, yet wet conditions that jolly England is known for!

In all reality, what makes this issue so difficult to see clearly is our insatiable dependency on carbon based fuels like petroleum and coal burning.  What to do?  What are we going to do?  Ultimately, the decision rests upon us.  How much carbon based energy do we require to be burned?  There are alternatives, like solar, wind and water power; but as of this date, each cannot produce the amount of energy that we demand when we look at cost efficiency and practicality.  Solar cells are still quite pricey these days and not everyone gets the amount of wind or water needed to sustain calm and/or arid areas.    What can we do to curb our dependency on carbon?  What is it that we are willing to sacrifice?

Herein lies the rub.

Just my thoughts,

Jack Douglas

What is Karst?

Karst is a specific land-form that is made from mainly carbonic rocks which slowly dissolves when exposed to slightly acidic water.  This is why Karstic landforms feature so many caves and sinkholes.  Other unique features include sunken streams (which resurfaces later on, sometimes miles away from sinking under), numerous springs (often times from streams resurfacing) and rolling hills alongside deep valleys (even though the rocks underneath may not be “folded”).

 (Geology Cafe)

We got the name “Karst” from the German “Karst.”  Karst, in German, comes from the Slovakian “Krass,” which is the name of a region in the Slovakian Republic that has many karstic features and is indeed Karstic.

What exactly causes an area to have these features such as caves and sinkholes?  It is basically carbon chemistry.  When slightly acidic water comes in contact with carbonic materials on bedrock, the carbons dissolve in the water.  The water sinks quickly down to the ground, dissolving other carbonic material that gets in the way.  Before long, holes (aka caverns or caves) are created under the surface.  Eventually, the roof of these caves will collapse. Above ground, this collapse is seen as a “sinkhole.”

Ten to fifteen percent of the Earth’s surface has this type of landform as the map from Flatrock.org will show (flatrock.org).  

Unfortunately, millions of people around the world populate karstic regions around the world.  This is does cause some environmental hazards. These hazards include sinkholes.  When a large cave collapses, sinkholes big enough to swallow houses and buildings could easily form very quickly and without warning.  Farmlands could be lost forever.

There is, however, another hazard associated with Karstic regions that really needs to be considered here.  That is the water filtering system underneath the population.  Water goes through the ground much quicker in Karstic areas, bypassing the normal filtering system that cleanses the water from many things that would contaminate it.  Water drawn up from a well could easily get polluted by a nearby septic tank that is leaking everywhere, or by fuel tanks up the road underneath the filling station there.  Loss of fresh clean water is a serious hazard!  Unfortunately, in a lot of Karstic areas, sinkholes are used as dumping grounds for garbage.  If it rains, you can bet that the groundwater is NOT going to be potable!

(Geography)

In the United States, Karstic areas are all over the place.  Major areas include the Appalachian Mountains in the Eastern U.S., the Ozark Plateau in the Mid-South, Southern Rocky Mountains in New Mexico, Edwards Plateau in Central Texas and just about the whole northern half of Florida.  On this blog page, I will concentrate on the first two (mainly the Ozarks, but a lot of the Appalachians as well), though I will also go elsewhere to see what all I can find.  

I personally love the Ozarks.  My family has lived in or at the edge of this plateau for about 6 generations now.  I also have ancestral roots going to the Southern Appalachians (like Tennessee and North Carolina).  This blog page is only a small part of a much bigger research into my family background.  However, information presented here will be general enough to where I can easily share the information and have others interested in matters of history, geology, anthropology, geography, meteorology, sociology, climatology and other fields thoroughly enjoy the material.   

Enjoy!

Bibliography

(n.d.). Retrieved February 16, 2013, from Geology Cafe: www.geologycafe.com

(n.d.). Retrieved February 16, 2013, from flatrock.org: http://images.search.yahoo.com/r/_ylt=A0PDoV7o2B9RElIAsk.jzbkF;_ylu=X3oDMTBtdXBkbHJyBHNlYwNmcC1hdHRyaWIEc2xrA3J1cmw-/SIG=12t9cumal/EXP=1361070440/**http%3a//flatrock.org.nz/archive/2011/Jul/30/a_la_recherche_du_temps_perdu/

Geography. (n.d.). Retrieved February 16, 2013, from Ohio Wesleyan University: www.owu.edu