Photogrammetric and LIDAR surveys on the Sciara del Fuoco to monitor the 2007 Stromboli eruption

Focused on the Stromboli Island, this research investigates whether airborne remote sensing systems, such as those based on digital photogrammetry and laser scanner sensors, can be adopted to monitor slope deformation and lava emplacement processes in active volcanic areas. Thanks to the capability of extracting accurate topographic data and working on flexible time schedule these methods can be used to constrain the regular and more frequent measurements derived from satellite observations. In this work we present an application dedicated to the monitoring of Stromboli volcanic edifice useful to obtain quantitative data on the geometry of deformation features and the displaced (failures and landslides) and emplaced (lava flows) volumes. In particular, we focused on the capability of extracting average effusion rates from volume measurements that can be used to validate or integrate satellite derived estimates are often affected by biases which are not easily detectable. Since 2001 a number of airborne remote sensing surveys, namely Digital Photogrammetry (DP) and Airborne Laser Scanning (ALS), were carried out on Stromboli volcano to obtain high resolution digital terrain models (DEM) and orthophotos characterized by sub-meter spatial resolution and time schedule suitable for monitoring the morphological evolution of the surface during the quiescent phases. During the last two effusive eruptions (2002-2003 and 2007) the surface modifications, suffered by the Sciara del Fuoco slope and by the crater area as a consequence of effusive activity, were quantified and controlled using the same methodologies. This work is mainly focused on the 2007 eruption but also accounts for analogies and differences with the 2002-2003 event being based on a multi-temporal quantitative analysis of the data collected from 2001 to 2007. The 2007 eruption involved the Sciara del Fuoco slope from the 27th February until the 2nd April: five flows produced a compound lava field including a lava delta on the shoreline and discharging most of the lava into the sea. The comparison of the 2007 DEMs with a pre-eruption surface (2006 LIDAR survey) allowed evaluating the total lava volume emplaced on the slope while two syn-eruption DEMs were used to calculate the average effusion rates through the eruption. Finally hypothesis on the lava discharge and slope instability mechanisms, which appear strongly connected, are formulated.