Integrated Surveys Of Active Volcanoes From Airborne, Bathymetric and Ground Based Data: The Examples Of Panarea and Albano (Italy)

Abstract

The Panarea and Albano active volcanoes (Italy) have been recently surveyed under multidisciplinary programs funded by the Italian Department of the Civil Protection and INGV. These complex volcanoes belongs to the perithyrrenian margin and the Aeolian arc system. Their activity, which produced in the past dramatic impacts on the environment as well as on human settlements, is known since historical times. At Panarea, on November 3th, 2002, a submarine gas eruption started in the shallow area between Lisca Bianca, Bottaro and Lisca Nera islets. A subaerial and sea bottom DEM of Panarea volcano was obtained merging aerial digital photogrammetry, aerial laser scanning, and multibeam bathymetry, carried out in 2002 and 2003. GPS data from the local network, show rates of motion and strain values typical of volcanic areas and in agreement with the NE-SW and NW-SE tectonic systems. The latter coincide with the main pathways for the upwelling of hydrothermal fluids. The general subsidence and shortening across the area inferred by GPS data, could be interpreted as the response to the surface of the deflation of the hydrothermal system reservoir which is progressively reducing its pressure after the 2002 gas eruption. The Albano volcano is a crater lake which is the deepest volcanic lake in Italy and fills the youngest maar of the Colli Albani volcano. The lake, which is only a few km far from surroundings of Rome, has undergone dramatic level changes and overflows about ~5800 yrs B.P. and likely in 398 b.C., when Romans excavated a tunnel drain through the maar wall. Hazardous lake rollovers and CO2 release are still possible because the Albano volcano still shows active geodetic ground deformation, gas emissions and periodic seismic swarms. In 2006, a very high resolution DEM from the combination of bathymetric and airborne surveys of the crater lake was performed. Results shows that the lake floor is made by coalescent and partly overlapping craters and wide flat surfaces separated by some evident scarps. The hazard implications for both volcanoes are discussed, particularly the issues related with the presence of ground deformation, gas exhalative points, CO2 accumulation, water rollover, which should not be excluded due to the seismicity of the area, and the features of the lake bottom.