Integrating archival data and remote sensing for the multi‑temporal analysis of the Salse di Nirano (Italy) mud volcano field

Abstract

Integrating heterogeneous historical and modern geospatial datasets provides an opportunity to extend the observation of active geological systems beyond the timespan covered by instrumental monitoring. This study applies this approach to the Salse di Nirano mud volcano field (Northern Apennines, Italy) to investigate its evolution over historical timescales. Historical cartographic and documentary materials, including an early twentieth‑century technical report and other archival records, were reprocessed to reconstruct past surface configurations while explicitly considering scale limitations, spatial resolution and interpretative uncertainties. These historical datasets were independently evaluated and then compared with recent high‑resolution products derived from Structure‑from‑Motion (SfM) photogrammetry and UAV‑based magnetometric surveys, enabling a multi‑temporal and multi‑sensor characterization of surface morphology and shallow subsurface geophysical signals. The integrated analysis indicates a persistent large‑scale spatial organization of the mud volcano system over more than a century, despite localized morphological evolution and
substantial anthropogenic modification. Magnetic anomalies show only partial correspondence with surface morphology and, together with available geoelectrical and gravimetric information, support a structurally heterogeneous subsurface characterized by multiple preferential fluid‑migration pathways rather than a single centralized conduit. Beyond the site‑specific results, the study shows that historical datasets, although intrinsically less precise than modern surveys, can provide useful quantitative and semi‑quantitative constraints when their internal consistency is independently assessed and their interpretation is restricted to an appropriate spatial scale. Their integration with modern remote‑sensing and geophysical observations therefore provides a means to extend the observational window of slowly evolving geological systems. The proposed strategy represents a step toward a transferable multi‑source workflow for investigating geomorphological and geophysical evolution over historical timescales, while explicitly accounting for the limitations and uncertainties associated with archival data.