High incidence angles of ASAR data reveal new insights for studying the 2004-2005 Mt. Etna eruption
Giuseppe Puglisi(1) and Francesco Guglielmino(1)
(1) Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma, 2, 95123 Catania, Italy
The ground deformation studies performed on Mt. Etna by using InSAR data are usually based on ERS1/2 and Envisat ASAR Swath-2 dataset. One of the main limits of these datasets is the poor information provided on the upper western flank of the volcano and along the western wall of the Valle del Bove area, where layover or shadow conditions typically occur, due to the steep topography in these areas. For these reasons, the possibility of exploiting the ASAR images collected at swaths from 3 to 7 is crucial to improve our investigations into the volcano dynamic.
In the framework of the DPC-INGV Project, carried out during the three-year period 2005-2007, a task was dedicated to investigating the possibilities of using new types of data for improving ground deformation modelling. To verify the possibilities of using high incidence angles of SAR images on Mt. Etna and in order to open new perspectives in the use of ASAR sensor in monitoring this volcano we used Swath-4 and Swath-6 SAR data provided by ESA, through the Category 1 Project n. 3885 ("Investigating Mt. Etna ground deformation by integrating geodetic and Envisat InSAR data).
During recent decades, continuous improvements in the monitoring systems have allowed gaining new insights into the behavior of Mt. Etna regarding the understanding of the dynamics of the volcano. In particular, the comparison between July 2003 and July 2004 GPS surveys shows an extremely interesting ground deformation pattern characterized by a very large increase in the rate of the seaward movement of the eastern and southeastern flanks, producing the rise of magma outpoured during the 2004-2005 eruption. This eruption started on September 7th, 2004 with the opening of an effusive vent at the base of the SE summit crater at about 3000 m altitude. In the following two days the eruptive fissure propagated downward towards the Valle del Bove (VdB) depression and the magma poured out inside this valley. The eruption lasted until March 12, 2005.
Preliminary analysis confirms the possibilities of using the ASAR data with high incidence angles, which improved the information especially on the summit volcanic area. In the meantime, the complete ground deformation database related to the 2003-2004 period, provided by GPS networks, will allow validating the new DInSAR maps, enhancing the modelling of the ground deformation sources related to the 2004-2005 eruption.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,