Comparison between magnetic anomalies and GPR images. North of La Alcudia site, Elche (Alicante)

When an archaeological site is extensive and the structures are supposed to be superficial (above of 3 metres), the most advisable geophysical prospection method is magnetic pseudo-gradient. To be explored, the North Alcudia zone was divided into 21 square sectors of 20 m by 20 m, and a potassium vapour magnetometer (GSMP-40) which absolute precision is 0.1 nT, was used. In each sector, the established distance between profiles was 1 m and the data acquisition was performed in a way, such it was obtained a sample each 10 cm (approximately). The aspects that influence the most in the interpretation of a magnetic anomalies map are the distinction between the two magnetic types (induced and remanent) materials, and the fact that the wide of these anomalies are always much bigger than the wide of the objects which produce that anomalies. In order to evaluate the detection grade provided by this kind of magnetograms, once they were obtained they, we was defined a group of areas to prospect in with GRP (SIR 200); with a 400 MHz antenna. Each area was acquired with 3D reflection methodology; that is with parallel profiles separated by 0.5 m and taking one sample each 2 cm. This work present a comparison between the results obtained with both techniques