Projects

As part of early planning for a proposed carpark development in Moore Park, NSW, a near-surface geophysical investigation was undertaken to assist in assessing the potential presence of a previously reported tunnel beneath the site. The investigation was designed to characterise shallow subsurface conditions to depths of approximately 10 m and to identify any anomalous low-stiffness zones that may indicate voids or disturbed ground.

The work was completed using the Multi-channel Analysis of Surface Waves (MASW) method. Nighttime has been chosen due to low presence of seismic noise at the site and surrounding areas (heavy machinery and traffic). A total of three MASW survey lines were acquired across the accessible areas of the site using a 48-channel geophone array mounted on a landstreamer, with seismic sources generated via stacked sledgehammer impacts. Sequential 1D MASW soundings were collected at 1 m intervals and processed into continuous 2D S-wave velocity sections.

The MASW survey successfully mapped the subsurface S-wave velocity structure, showing predominantly horizontally layered conditions across the site. One localised low-velocity zone was detected along one survey line, which may represent a soft or infilled zone or, potentially, collapsed tunnel.