Ocean Bottom Seismometer - OBS
Ocean Bottom Hydrophone - OBH
Sensors at the sea floor are used to observe acoustic and
seismic events.
Since the OBS/OBH works with hydrophones as well as with geophones,
both names, OBS (Ocean Bottom Seismometer) and
OBH (Ocean Bottom Hydrophone)
are used for this observation and registration system. Combined with
marine Multi-Channel Seismic (MCS) profiles,
OBS is an economical alternative to ship-bounded
Common MidPoint (CMP) methods in seismics.
One aspect as an example:
for MCS/OBS one vessel including the seismic array is necessary,
while CMP requires two vessels each equiopped with seismic array.
OBS may be equipped with a maximum of a three-component geophone
in addition to a hydrophone, and thus it needs a capacity of more than
144 Mbyte, which would be the minimum for an adequate MCS profiling.
In a typical survey, the instruments should be operational for several
days, which requires a data storage capacity of more than 500 Mbyte.
Other experiments, such as tomographic investigations within a 3D-survey
or seismological monitoring, demand even larger capacities.
Seismic and acoustic signals may be caused by different sources,
by earth quakes and tremors as well as by artificial sources.
Computing and analyzing the data yields information about the kind of
source and, in case of natural seismic events, the geophysics and geology
of the sea floor and the deeper crust.
The deployment of OBS along a profile will give information about the
deep structure of the Earth's crust and upper mantle in offshore areas.
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