A Seismic Array in Western Australia

17 Jan

Gaiacode has just delivered the first batch of seismometers for a new mobile seismic array in Western Australia (WA). Modelled after the highly successful EarthScope Transportable Array, which operated in the United States from 2004 to 2018, the so called WA-Array will roll across the largest Autralian state. A total of 165 seismometers will be deployed in a network with approximately 40 km station spacing in a regular grid. After collecting passive seismic data for a year, the stations will be dismantled and moved to the next location. Using this leap frogging method, the WA-Array operators of the Geological Survey of Western Australia (GSWA) hope to cover their vast territory completely within the next decade.

Imaging the Moho and the upper mantle

The WA-Array is expected to record local, regional and teleseismic signals, which will be analysed to answer many open scientific questions about the region. By deploying this movable array, the scientists have several objectives. Among others, they want to image the Moho and lithosphere–asthenosphere boundary. Doing this they hope to model the deeper crust and the subcontinental lithospheric mantle in the region. In addition they want to find new corridors for mineral exploration and lastly add to the National Seismic Hazard Assessment of Australia.

WA Array Map

A map of Western Australia showing the distribution of seismic sensors. The regular pattern of grey dots in the background depicts the locations of the new WA-Array (map from Murdie et al., 2022)

Gaicode has contracted to deliver approximately one quarter of all seismometers used in the WA-Array. GSWA has decided to purchase 40 THETA TT120 portable seismometers. The low noise high dynamic range broadband feedback seismometer is based on a truly rectilinear suspension system which does not require mass locking. We have delivered the first batch of 20 sensors with the other 20 expected to follow soon.

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References

  • Ref 1 USHER, M.J., BURCH, R.F. and GURALP, C.M., “Wide-band Feedback Seismometers”, 1979. Physics of the Earth and Planetary Interiors, 18: 38-50.
  • Ref 2 M,J, USHER and C.M. Guralp, “The design of miniature wideband seismometer” Geophys. J.R. ast. Soc. (1978)-55 (605-613) ,
  • Ref 3 GURALP, C.M., “The Design of a Three-component Borehole Seismometer”, 1980. Ph.D. Thesis, Univ of Reading.
  • Ref 4 GURALP C.M. Patent Application, No: 7909579 Filed: 19th March 1979 (declaration priority from Appln No: 10279/78 Filed: 15th March 1978) “Vertical Seismometer”.
  • Ref 5 GURALP C.M. United States Patent Application Number: 4,280.206 March 1979. SEISMOMETERS.
  • Ref 6 GURALP C.M. UK Patent Application GB 2-144-287-A. July 1983 Analog-to-digital converters for Seismometers. The National Research Development Corporation (UK)
  • Ref 7 GURALP C.M. UK Patent Application No. 1900719.4; Title: Infrasound Detector [M&S-IRN.FID4315516]