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New Madrid Earthquake Sequence Dec 1811–Feb 1812

  1. Nov 7, 2011 #1

    Astronuc

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    We're approaching the bicentennial anniversary of the largest earthquake and swarm east of the Rocky Mountains, at least in recent history. Coincidentally, Oklahoma has just had it's largest earthquake in the state's history.

    Bicentennial of the New Madrid Earthquake Sequence December 1811–February 1812

    http://pubs.usgs.gov/gip/134/


    The seismic activity can abruptly and dramatically change anywhere in the world, as was witnessed in the Canterbury region around Christchurch, NZ on Sept 4, 2010, although one might expect such activity in that part of the world which sits astride the boundary of the Australia and Pacific plates.

    The middle of the US has been considered stable, so strong earthquakes are rather surprising.

    It will be interesting to see what follows the recent earthquakes in Va and Ok.
     
  2. jcsd
  3. Nov 7, 2011 #2

    davenn

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    "Had been considered stable...." may be a better phrase ;)

    My memories go back to my visit to the USGS office in Boulder, CO. in 1999. Talking to Dr Mark Meremonte and others there who had done/still doing (at that time) considerable research on the New Madrid Fault Zone. The zone is currently displaying thrust and strike-slip tectonics but appears to have undergone several cycles of extension and compression over geological history. It seems the area is what is termed a "Failed Continental Rift Zone".

    Quite amazing really ... cuz if it has really developed I wonder how far north the rifting would have gone and what it would have looked like. Maybe a bit like the Gulf of California, which of course is extensional.

    cheers
    Dave
     
  4. Nov 7, 2011 #3

    Evo

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    There was a 4.2 aftershock about an hour ago.
     
  5. Nov 7, 2011 #4

    davenn

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    hi Evo


    haha ... you spoke it into being mate ;)


    Magnitude Mb 4.7

    Date-Time
    Tuesday, November 08, 2011 at 02:46:57 UTC
    Monday, November 07, 2011 at 08:46:57 PM at epicenter

    Location
    35.541°N, 96.754°W

    Depth
    5 km (3.1 miles)

    Region
    OKLAHOMA

    Distances
    28 km (17 miles) NNE of Shawnee, Oklahoma
    69 km (42 miles) SSE of Stillwater, Oklahoma
    70 km (43 miles) E of OKLAHOMA CITY, Oklahoma
    71 km (44 miles) ESE of Guthrie, Oklahoma

    USGS

    This has really been the year for significant events outside of the western states (CA,OR,WA)
    much more activity than in recent years
    Dave
     
    Last edited: Nov 7, 2011
  6. Nov 7, 2011 #5

    Evo

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    Thanks Dave!
     
  7. Nov 8, 2011 #6

    davenn

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    well I didnt record that one far too far and too small.
    But I did record the Mw6.9 NE of Taiwan that occurred shortly after the OK event

    cheers
    Dave
     
  8. Nov 24, 2011 #7
    It also sits right in between the base of the Appalachian Mountains and the Interior Highlands/Ouchita buried mountain belt. I know the Appalachian Mts. are linked to the break of a super continent, and the burried Ouchita Mts. (Oklahoma and Texas) and the Interior highlands of Arkansas are related to the opening of the Gulf of Mexico.

    However I have heard that the two could be related. Could the Mississippi rift be a result of these two events?
     
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