AusMT / surveys / Hanekop Eastern Queensland 2003

Hanekop Eastern Queensland 2003 BBMT 1 / GDS 1 / LPMT 33

Magnetotelluric and geomagnetic depth sounding survey · Northern Territory, Queensland · Institut fuer Geophysik, Georg-August-Universitaet Goettingen

Part of the Australia legacy GDS collection

Thirty-eight long-period recording sites were laid out across central Australia between July and October 2003, from 133.

About this survey

Thirty-eight long-period recording sites were laid out across central Australia between July and October 2003, from 133.800 to 143.000 degrees east and 19.668 to 24.681 degrees south, a footprint 949 km east to west and 555 km north to south straddling the Queensland and Northern Territory border. The array is the central Australian campaign of Ole Hanekop's 2006 Goettingen doctoral thesis, Large scale resistivity surveys combining magnetic and magnetotelluric observations: Examples from central Australia, supervised by Karsten Bahr and Fiona Simpson, with field help from Max Moorkamp. Ten five-channel instruments recorded two horizontal electric and three magnetic components: Goettingen RAP data loggers with Magson fluxgate magnetometers and Ag/AgCl electrodes, nine held on long-period sites for six to eight weeks and one roving between overnight sites at about 50 km infill inside a 200 km backbone. The fastest sampling was 2 s, giving a shortest period of 8 s on the long-period loggers. Processing was the Goettingen remote reference, cross-checked against the Egbert and Booker code; the geomagnetic depth sounding was finally referenced to site ARG. The campaign was designed to extend the six central Australian sites of Simpson (2001), and the thesis reports three-dimensional conductivity models built from it.

THIS RECORD SERVES VALUES READ FROM THE FIGURES OF THAT THESIS. The thesis publishes no numeric table of any transfer function, so the figures are the only surviving public form of these soundings, and what is served is the plotted value rather than the value Hanekop computed. Each number was read from the vector drawing operators of the figure, not digitised from pixels. Thirty-five stations are served. Thirty-four carry apparent resistivity and phase in both off-diagonal components, converted to impedance, at 1,371 estimates between 0.063 and 66,510 seconds, from Figures A.2, A.3 and A.4 on pages 95 to 97. Thirty-three carry real and imaginary induction arrows at up to four periods, 16, 64, 256 and 1,024 seconds, 468 numbers at 117 site-periods, from Figure 4.4 on page 50. Station ARD carries arrows only: both its sounding panels plot two markers of one component in one frequency column, so neither was read. Stations CLO and MON carry a sounding and no arrow, because Figure 4.4 draws none for them; MON lost its magnetic and electric channels after 15 hours, which page 93 records. Three of the thirty-eight Table A.1 sites are served by nothing, ARGAMT, COP and DAV; the electric fields were lost at COP and at DAV.

There is no Zxx and no Zyy, because no figure draws them, and none has been synthesised. Impedance variances come from the plotted error bars read as one standard error, which the thesis nowhere defines; any correction to that reading is a single multiplicative constant on every variance here. The tipper carries no uncertainty, because Figure 4.4 draws none. The geomagnetic depth sounding perturbation tensor, which is the actual GDS result of this campaign, survives only as raster images in Figures A.5 and A.6 and cannot be recovered from the document at any useful precision.

The frame is geomagnetic. Page 43 states that acquisition was in the geomagnetic coordinate system and pages 94 to 97 label the curves unrotated, so every file declares its own frame by carrying the magnetic declination at its site as a uniform ZROT and TROT with the HMEAS azimuths agreeing. Declination was computed from IGRF at the Table A.1 coordinate for epoch 2003-09-01 and runs from 5.0749 degrees at ARL to 7.3699 degrees at WIN. Nothing in any file is rotated.

A prior holding of 33 tipper-only files, which reached AusMT through a Geoscience Australia data drop whose own upstream is unestablished, is kept verbatim beside the package and compared row by row against what is served. The two agree to a median vector difference of 0.0047 over 230 arrows and 31 of the 33 stations agree to 0.017 or better, but the prior values are quantised to 0.01 in magnitude and one degree in azimuth, carry no statement of scale, and run a median 1.0204 times the values served here. Station BRE is the one station whose prior file is defective: it reproduces recovered values under the wrong period labels.

Data and downloads

Stations (35)

Contributors and organisations

Organisation

Institut fuer Geophysik, Georg-August-Universitaet Goettingen

Licence

CC BY 4.0

Instruments

Georg-August-Universitaet Goettingen RAP data logger (Steveling and Leven, 1992)
Magson fluxgate magnetometer
unknown Ag/AgCl electrodes
Georg-August-Universitaet Goettingen modified RAP data logger with induction coils (Jantos, 1999)

Processing

University of Goettingen remote reference (Gamble et al., 1979)

Funding

Goettingen Graduate School of Physics
Geophysics Institute, University of Goettingen

Publications

Hanekop, O. (2006). Large scale resistivity surveys combining magnetic and magnetotelluric observations: Examples from central Australia. Doctoral dissertation, Georg-August-Universitaet zu Goettingen. 10.53846/goediss-2673

Identifiers and provenance

Machine-readable survey record · catalogue schema mtcat 2.0