Sonic Waveform Data
Science operator: Texas A&M University
Hole: U1522A
Expedition: 374
Location: West Antarctic Ice Sheet (Ross Sea)
Latitude: 76° 33.2262' S
Longitude: 174° 45.4652' W
Logging date: January 27-28, 2018
Sea floor depth (driller's): 568.5 m DRF
Sea floor depth (logger's): 568.0 m WRF
Total penetration: 1270.3 m DRF (701.8 m DSF)
Total core recovered: 279.57 m (39.8 % of cored section)
Oldest sediment recovered: Late Miocene
Lithology: Massive clast-rich muddy to sandy diamict and clast-poor sandy diamictite
ACOUSTIC TOOL USED: DSI (Dipole Sonic Imager)
Recording modes: Monopole P&S and Upper and Lower Dipole (all passes).
Remarks about the recording: none.
MONOPOLE P&S MODE: measures compressional and hard-rock shear slowness. The monopole transmitter is excited by a high-frequency pulse, which reproduces conditions similar to previous sonic tools.
UPPER DIPOLE MODE: measures shear wave slowness using firings of the upper dipole transmitter.
LOWER DIPOLE MODE: measures shear wave slowness using firings of the lower dipole transmitter.
Acoustic data are recorded in DLIS format. Each of the eight waveforms generally consists of 512 samples, each recorded every 10 (monopole P&S) and 40 microsec (dipolemodes), at depth intervals of 15.24 cm (6 inches).The original waveforms in DLIS format are first loaded on a virtual PC machine using Schlumberger's Techlog log analysis package. The packed waveform data files are run through a module that applies a gain correction. After they are exported from Techlog in LAS format they are converted into binaryand GIF format (images) are cconverted using in-house software.
Number of columns: 4097
Number of rows: 3868 (downlog)
Number of rows: 4217 (main run)
Number of rows: 893 (repeat run)
The following files have been created:
DSI from MSS/HRLA/DSI/HLDS/EDTC-B/HNGS (Downlog, drill pipe at 89.5 m WMSF)
374-U1522A_ldip_d.bin: 0-597 m WMSF
374-U1522A_mono_d.bin: 0-597 m WMSF
374-U1522A_udip_d.bin: 0-597 m WMSF
DSI from MSS/HRLA/DSI/HLDS/EDTC-B/HNGS (Main pass, drill pipe at 74 m WMSF)
374-U1522A_ldip_main.bin: 0-650 m WMSF
374-U1522A_mono_main.bin: 0-650 m WMSF
374-U1522A_udip_main.bin: 0-650 m WMSF
DSI from MSS/HRLA/DSI/HLDS/EDTC-B/HNGS (Repeat pass, recorded open hole)
374-U1522A_mono_rep.bin: 515-650 m WMSF
374-U1522A_ldip_rep.bin: 515-650 m WMSF
374-U1522A_udip_rep.bin: 515-650 m WMSF
The sonic waveform files are depth-matched and depth-shifted to the seafloor (-568 m) . Please refer to the 'depth_matches' folder in the hole index page for the depth-matching values and to the "DEPTH SHIFT" section in the standard processing notes for further information.
Additional information about the drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition report, Proceedings of the International Ocean Discovery Program, Expedition 374.