Earth Science Earthquakes in Alabama & Colorado?

Discussion in 'Earth Science' started by justme1640, Nov 8, 2004.

  1. justme1640

    justme1640 Member

    To our experts -- are the earthquakes in Alabama and Colorado caused or influenced by the one off Vancover (sp?)

    thanks
    jm
     
  2. Zsandmann

    Zsandmann Premium Member

    Could you post a link to the event you are talking about. I am a geophysicist, I live in Colorado and am from Alabama and I havent heard about or felt any eartquakes in either place. But to give you a quick answer just geologically speaking, yes a canadian earthquake COULD cause an earthquake in CO under the right conditions, but probably not in Alabama. Explanation: CO is underlain by igneous and metamorphic rocks, these are very dense and allow for good seismic wave propagation, while AL is mostly underlain by sedimentary rocks like sandstone and limestone, these are low density and do not spred seismic waves very well. Therefore, AL would likely not be disturbed by seismic waves from Canada. Also, AL and CO are in different seismic regions linked by different fault systems so they would not likely experince quakes from something that affected the other system.
     
  3. justme1640

    justme1640 Member

  4. Zsandmann

    Zsandmann Premium Member

    k I see them on the map, doubt they are related however.
     
  5. BlackJackal

    BlackJackal New Member

  6. Zsandmann

    Zsandmann Premium Member

    Snip from your first link:
    The New Madrid Seismic zone is very interesting because it is an intercratonic fault system, it is in a continent. Most fault systems are on plate and thus continental boundries. The New Madrid is believed to be a failed rift, or place where the continent tried to break in half. However, as someone in your thread suggested these earthquakes are not on the New Madrid zone but actually the Appalachian Seismic belt. The Applachian extend through Mississippi but are buried about midway through Alabama. If the quakes are not mine or well related, see below, Id say they are small quakes on the App. Line. It is still active after all, just not lately.

    From your second link:
    The above is one of the first things I thought of when I read this thread. There are MANY coal mines in Alabama, sometime the old ones collapse and can cause magnitude 2-3 earthquakes. Also either pumping or presurizing gas or water wells can lubricate faults and cause small quakes. It is common practice to force water or recycled gases into adjacent wells to a productive well to create a pressure gradient and thus increase production. When the pressure reaches a rocks fracture pressure small quakes result.
     
  7. justme1640

    justme1640 Member

    Thanks
    Like I said before you always teach me something new and you always make it interesting too.
    jm