Publication Date:
2022-05-25
Description:
The Seafloor Borehole Array Seismic System (SEABASS) has been developed to
measure the pressure and three dimensional particle velocity of the VLF sound field (2-50HZ)
below the seafloor in the deep ocean (water depths of up to 6km). The system consists off our
three-component borehole seismometers (with an optional hydrophone), a borehole digitizing
unit, and a seafloor control and recording package. The system can be deployed using a wire line
re-entry capability from a conventional research vessel in Deep Sea Drilling Project (DSDP)
and Ocean Drilling Project (ODP) boreholes. Data from below the seafloor are acquired either
on-board the research vessel via coaxial tether or remotely on the seafloor in a self-contained
package. If necessary the data module from the seafloor package can be released independently
and recovered on the surface. This paper describes the engineering specifications of SEABASS,
the tests that were carried out, and preliminary results from an actual deep sea deployment.
Ambient noise levels beneath the seafloor acquired on the Low Frequency Acoustic-Seismic
Experiment (LFASE) are within 20dB of levels from previous seafloor borehole seismic
experiments and from land borehole measurements. The ambient noise observed on LFASE
decreases by up to 12dB in the upper 100m of the seafloor in a sedimentary environment.
Description:
This work was carried out under
JHU Contract # 602809-0
and under
ONR contracts
#N00014-89-C-0018, #N00014-89-J-1012,
and #N00014-90-C-0098.
Keywords:
Very Low Frequency (VLF) sound fields (2-50 Hz)
;
Seafloor Borehole Array Seismic System (SEABASS)
;
Deep Sea Drilling Project (DSDP).
;
Low Frequency Acoustic-Seismic Experiment (LFASE)
Repository Name:
Woods Hole Open Access Server
Type:
Working Paper
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