Rotella, G.

We present the results of a combined analysis of remote sensing and geophysical ‐ geotechnical data carried out in the Acque Albule Basin, a sinkhole prone area located close to the city of Roma, where a wide travertine wedge is present. We carried out geophysical measurements and borehole drillings over two test areas to image the subsoil where paroxysmal sur fi cial dynamics occur. One site is marked by subsidence occurring at least since the early 2000s, whereas the other site hosts the “ La Regina ” and “ Colonnelle ” sinkhole lakes, which discharge sulfur ‐ carbonated waters. The stability of these two sites threatens highway, railway, and airport facilities, and this study helps to assess the geological hazard. For example, InSAR and LiDAR data helped de fi ne wide scale subsidence over the last 20 years and previously undetected small ‐ scale morphologies. Geophysical measurements of the latter revealed shallow and deep dissolution affecting the travertine and driving sur fi cial paroxysmal events. Both study sites were found to lie inside a large depression located at the junction between Jurassic carbonate and Plio ‐ Pleistocene units in association with paleo karst morphologies in the travertine deposits and affected by the present ‐ past spillage of sulfurous waters. Given these elements, multidisciplinary geophysical observations are crucial for assessing and mitigating the geological risk and guiding land use planning and management.

Sinkhole occurrence along the Tyrrhenian margin of the Central Apennines is of great importance for applied research, land management and civil protection. This study reports on GPS-altimetry magnetic, gravity, geoelectric, seismic, and soil gas measurements of a rapidly developing sinkhole near the Guidonia military airport. The measurements revealed an elliptical 2-m depression elongated 220 m in the NNE-SSW direction with the minor axis of 110 m. In spring of 2013, two vertical cavities formed in the eastern and northeastern flanks of the depression whose depths and shapes are rapidly evolving with the formation of widespread fracturing along the same side. The geophysical observations image the developing sinkhole to a depth of some 50 m, the presence of the Travertino lithotype around the depression (down to at least 40 m), and the lack of this lithotype below the lowered area. The sinkhole's evolution appears to be structurally controlled by local and regional faulting. These results are useful for designing further geophysical, geotechnical and geochemical studies to monitor the sinkhole's evolution and to assess the hazard it presents in densely urbanized area.