Quantitative Interpretation of Magnetic Anomalies from Thick Bed, Horizontal Plate and Intermediate Models Under Complex Physical‐Geological Environments in Archaeological Prospection

Abstract

Magnetic prospecting is one of the most widely used methods for archaeological prospection in the world. Noise both of natural [main factors are inclined magnetization, complex geological (archaeological) structure of investigated sites, and uneven terrain relief] and artificial origin (different iron-containing targets, electric power lines, etc.) strongly obscure interpretation of observed magnetic anomalies. For quantitative analysis of magnetic anomalies produced by archaeological targets under aforementioned conditions a non-conventional interpreting system has been developed. Methodology of magnetic anomalies interpretation from models of thin bed and horizontal circular cylinder (sphere) in conditions of oblique magnetization, rugged relief and unknown level of the total magnetic field by the use of improved versions of characteristic point and tangents has been earlier suggested. However, many archaeological targets have geometrical form of thick bed, thin horizontal plate and intermediate between these two models. In this paper methodology of magnetic anomalies produced by thick bed models in complex environments is explicitly described. It is shown that quantitative analysis of magnetic anomalies due to intermediate (between the thick bed and thin horizontal plate) targets could be successfully carried out by the use of methodology developed for the thick bed model. In the case of thin horizontal plate with a large horizontal extent, the two measured anomalies may be interpreted as anomalies from thin beds. The interpretation methodology was successfully tested both on typical models and on real archaeological targets with some success.

Magnetic and GPR Data Modelling via Multiscale Methods in San Pietro in Crapolla Abbey, Massa Lubrense (Naples)

“…Significant anomalies are produced by different kinds of common archaeological targets, such as ditches, storage pits, foundations and walls. These latter could have very different magnetic responses; for example, masonry made up of limestones could have negative contrast with topsoil (Eppelbaum 2015; Smekalova, Abrahamsen, and Voss 1993), while earthen structures commonly generate positive contrasts. It is worthwhile to point out that buried structures related to buildings are easily detectable due to their susceptibility contrast with soils and regular shapes (Florio et al.…”

Quantitative Examination of Piezoelectric/Seismoelectric Anomalies from Near-Surface Targets

“…Careful analysis of piezoelectric/seismoelectric anomalies shows (see Section 3) the possibility of application for quantitative analysis of these effects in advanced methodologies developed for magnetic prospecting in complex physical-geological conditions: rugged terrain relief, oblique polarization and complex media [43][44][45][46][47][48]. Employment of these methodologies (improved modifications of tangents, characteristic points and areal methods) for obtaining quantitative characteristics of ore bodies, environmental features and archaeological targets (models of horizontal circular cylinder, sphere, thin bed, thick bed and thin horizontal plate were utilized) may have significant importance [49].…”

“…Values recorded over the host rocks (clays and shales of basic composition) were close to zero. The observed piezoelectric anomaly was firstly quantitatively interpreted by the use of methodologies developed in magnetic prospecting for the model of thick and intermediate bodies [48]. Calculated PM here is ≈95 µV.…”