Wireline Sonic Waveform Data


IODP-MSP drilling and logging contractor: ESO

Hole: M0004B

Expedition: 302

Location: Lomonosov Ridge ( Arctic Ocean )

Latitude: 87° 52.018' N

Longitude: 136° 10.475' E

Logging date: September 4, 2004

Sea floor depth (driller's): 1289.70 mbrf

Sea floor depth (logger's): 1291.00 mbrf

Total penetration: 218.00 mbsf

Total core recovered:  7.31 m (66.50 % of cored section)

Oldest sediment recovered: Middle Eocene

Lithologies: Clays to silty muds



TOOL USED: BHC (Borehole Compensated Sonic Tool)

Remarks about the recording: The velocity data show no indication for cycle skipping and so no corrections have been applied.


Acoustic data are recorded in DLIS format. Each of the four waveforms consists of 120 samples, each recorded at depth intervals of 15.24 cm (6 inches). The original data in DLIS format is first loaded on a Sun system using GeoFrame software. The waveform data files are then converted into ASCII and finally binary format.

Each line is composed of the entire waveform set recorded at each depth, preceded by the depth (multiplied by 10 to be stored as an integer). In the general case of 4 waveforms with 400 samples per waveform, this corresponds to 1 + 4x500 = 2001 columns. In this hole, the specifications of the files are:

Number of columns: 481

Number of rows: 3441 (Pass 1)

Number of rows: 4881 (Pass 2)


All values are stored as 'signed short integers' (= 16 bits signed).

Each file can be viewed directly as an image with Spyglass transform or NIH image on Macs and PCs, or Fortner transform or Khoros on UNIX) - where it has to be opened as either 'raw' or 'binary matrix'. Any image or signal-processing package should also allow viewing it.


The following files have been loaded:

BHC from FMS/BHC/GPIT/NGT/SGT (Pass 1, pipe at ~1357 mbrf)

302-M0004B_p1.bin: 1333.25-1508 mbrf


BHC from FMS/BHC/GPIT/NGT/SGT (Pass 2, pipe at ~1357 mbrf)

302-M0004B_p2.bin: 1262.79-1510.74 mbrf


The sonic waveform files are not depth shifted to a reference run or to the seafloor. For depth shift to the sea floor, please refer to the DEPTH SHIFT section in the standard data processing documentation file.


NOTE: For users interested in reading and converting the data to a format more suitable for their own purpose, the fortran declaration used to open the file *.bin would be:


open (1, file = *.bin,access = 'direct', recl = 2*(1+nwav*nsamples))


where nwav is the number of waveforms (4 or 8) and nsamples the number of samples per waveforms (see above).

If the total number of depths where waveforms have been recorded is ndepth (for a 150 m interval with data every 15cm, ndepth would be 1000), a generic loop to read the data would be


do k = 1, ndepth


read(1, rec=k) iz, (data(i), i = 1, nwav*nsamples)





In such a case, the file dimensions will be ndepth rows by nwav*nsamples+1 columns .


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 Integrated Drilling Program, Volume 302. For further questions about the logs, please contact:


Jennifer Inwood

Leicester University

Phone: 011-44-116-252-3327

Fax: 011-44--116-252-3918

E-mail: iodp@le.ac.uk


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E-mail: logdb@ldeo.columbia.edu