Borehole Seismic Data
Science operator: CDEX-JAMSTEC
Hole: C0024A
Expedition: 358
Location: Nankai Trough (NW Pacific Ocean)
Latitude: 33° 2.04396' N
Longitude: 136°47.3991' E
Logging-while-drilling date: March 6-10, 2019
Total
penetration: 4739 m LRF (869 m LSF)
SEISMIC TOOL USED: SeismicVision (Logging-While-Drilling)
The SeismicVision tool records seismograms using a hydrophone and a three-component geophone in the tool, and a surface source and hydrophone. The source used during expedition 358 consisted of an array of six airguns firing 5.4 m below sea level. The surface hydrophone was suspended 1.27 m below the airguns (or 6.67 m below sea level), and the zero time of the waveforms was corrected to sea level. The SesimicVision data were acquired while the pipe was being recovered. Time correlation of the shots was ensured using high-precision clocks at both surface and downhole hydrophones. Ten shots were fired every 15 seconds at each level. Thirty four levels were recorded at hole C0024A. For each shot, the tool recorded the pressure at the hydrophone and acceleration seismograms at the three-component geophone and calculated a vertical stack of the shots. It also picked and recorded the first compressional P-wave arrival in the stacked seismogram.
The data was provided by Schlumberger in SEGY format. All the data in
the SEGY files are sorted shot by shot (i.e. chronologically).
Additional information about the drilling and logging operations can be found in the Site Expedition Report and in the Methods section, Proceedings of the International Ocean Discovery Program, Expedition 358. Results of the Seismic Vision experiment are provided in the checkshot report available online in the Documents section of Hole C0024A index page.
For questions about the logging operations and the processing performed onboard, please contact:
Yukari Kido
E-mail: ykido@jamstec.go.jp
For database-related questions you may contact:
Cristina Broglia
Phone: 845-365-8343
Fax: 845-365-3182
E-mail: Cristina Broglia
Tanzhuo Liu
Phone: 845-365-8630
Fax: 845-365-3182
E-mail: Tanzhuo Liu