Proposed NSF Initiative in Oceanic Mantle Dynamics

The ultimate goal of the proposed Ocean Mantle Dynamics program is to map the 
pattern of general circulation in the mantle associated with convection in 
the Earth's interior. A coordinated, decade-long program centered on 
seismological imaging in the oceans that is allied with advances in 
geochemistry, petrology, geophysics and geodynamical modeling will provide an 
effective and efficient attack on the problem of determining the general 
pattern of circulation in the mantle.
There are three prongs to the envisioned attack:  focused, interdisciplinary 
investigations of individual features of the circulation system; leapfrogging 
arrays of ocean-bottom seismometers (OBS) that will systematically fill in 
gaps in global seismic coverage; and an offshore array of seismometers that 
will complement USArray, extending coverage across the continental shelves 
and into the adjacent ocean basins.  

Recommendations of a recent planning workshop include: (1) running one to two 
major, interdisciplinary experiments per year using on the order of 50 or 
more wide-band OBS in passive deployments, one or more of which could be 
directed toward the regions around Antarctica; and (2) two leapfrogging 
arrays of 25 instruments each that will fill in gaps in global seismic 
coverage with one year deployments, including the Southern Oceans.  The 
leapfrogging arrays are planned to be shallowly-buried OBS which are much 
quieter at long-periods on the horizontal components than seafloor OBS s if 
there are any bottom currents (i.e., almost anywhere).