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Table of Contents

Illustration of underway geophysical data acquisition during Expedition 324 (Kang et al., 2010, doi:10.2204/iodp.proc.324.108.2010).

Overview

The primary function of the Underway Geophysics lab is to acquire navigation and bathymetric (3.5 and 12 kHz) data, and provide and maintain the sound sources used for check shots and vertical seismic profile experiments. In addition to their scientific uses, geophysical data are used to ensure the drilling safety of the ship by confirming site positions and identifying potentially dangerous seafloor and subseafloor characteristics. The lab also supports downhole vertical seismic profiling and can collect magnetic data while underway.

Instruments

Seismic Sound Sources

  • Sercel 210 in3 GI Gun pneumatic sound source: configurable to "True GI Mode" and up to 255 total in3; used as a sound source for downhole logging operations and towed seismic surveys
  • Sercel G. Gun Parallel Cluster pneumatic sound source: the cluster is composed of two 250 in3 G. Guns separated by 1 meter; used as a sound source for downhole logging operations

Bathymetry

  • Knudsen Sounder Suite for CHIRP 3260 Sub-bottom Profiler using (i) 3.5 kHz frequency obtained with a 12 x TR-109 transducer array driven by a 10 kW power amplifier; (ii) 12 kHz frequency obtained with an EDO-323C transducer
  • Transducers are housed in the forward sonar dome

Navigation

  • Integrated navigation software: EIVA NaviPac and Helmsman; in-house Site Fix LabVIEW application
  • Two Trimble SPS356 GNSS Modular Receiver with Trimble GA530 antenna (GA830 also available)

Magnetics

  • Marine Magnetics SeaSpy M-SS1001 Towed Magnetometer

Bathymetry

Magnetometer

Navigation

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