This paper presents an example of using the ground-based synthetic aperture radar (GBSAR) technique for the emergency monitoring of a deep foundation excavation. The process includes a quality evaluation for the interferometric data acquired by the IBIS-L radar from Ingegneria Dei Sistemi S.p.A. Atmospheric effects were eliminated through calibration with ground control points (two triangular reflectors) to improve the measuring accuracy of the emergency monitoring. Accuracy of the data obtained was then compared at six check points between the GBSAR technique and a Leica total station TC2003 with prisms. The results indicate that the GBSAR technique is a suitable method of emergency displacement monitoring within a deep foundation excavation and has several significant advantages. These include a higher level of accuracy, near real-time monitoring intervals, and site-wide displacement maps obtained for each observation sampling interval.