Day 0: June 9
Welcome to the Mississippi River 2011 Moonwalk. In this blog we highlight happenings on our research as we drift backwards down the
Mississippi River performing our marine seismic survey. Information on the project can be found on the main page.
Today was preparation day as we loaded the US Army Corps of Engineers (USACE) motor
vessel (M/V) Strong. The M/V Strong is a buoy tender for the Corps, but was recently used to transport
the explosives upriver to Birdseye Point where a MS River levee was blown to release
floodwater during this unprecedented flood. Floodwaters have since receded and the MS River is back within its banks, at least
proximal to Memphis, TN, which is our starting point for this journey. We are headed south to the AR/LA state line…just north of Jackson, MS.
We unloaded the equipment onto the Strong, and began the process of connecting and
running communication and supply line cables between the equipment that will be deployed
in the river and the computers and air supply. In case you are not familiar with our past MS River work between Cape Gerardo, MO
and Memphis, TN, we deploy: (1) a Chirp that lets us see the shallow sediment layering
beneath the riverbed bottom to ~50 ft and (2) streamer with energy source (air bubble)
that lets us see about 1 mile deep into the earth’s surface.
So what are we looking for when we process the data? Well much of the deep sediment in the MS River valley was deposited in an inland
sea environment over the last 90 million years. In this type of environment, the sediment settles slowly and evenly, relatively speaking. So without any disruption, we’d expect to see the layers (sand/clay/rock) flat and
stacked like pancakes.
But as you’ve read in the project description, tectonic forces are at play here, and
the subsurface is faulted. This means that the layers are broken in places and shifted up or down. We are looking for those faults to determine where we see deformation in the inner
continent, how those same forces are playing out today and eventually what controls
seismicity so far away from plate boundaries. Knowing this we can determine risk and work to minimize those risks through planning
We encourage you to follow along with us as we travel down the MS River. Our blog is not technical, but will be an enjoyable read.