Monitoring Volcanic Areas Using Interferometric Methods with Ground Truth

Since SAR interferometry was introduced in the 1980s, it has become a standard method for deformation monitoring, especially for detecting surface deformations with precisions of centimeters or even millimeters. In reality, this level of accuracy is hard to achieve due to several errors including atmospheric delay, orbit error, an uncertain height reference and processing errors [1]. To eliminate these complex errors, parametric time series methods were developed using stable persistent scatters (PS), such as PS-InSAR, SBAS and recent PSP techniques [2][3][4]. The PS-based methods were successfully used in urban areas to detect long-term surface deformation [5][6]. Our goal is to apply this method in volcanic areas, i.e. mountainous areas where large height changes occur. Atmospheric stratification is one of largest uncertainties in the measurements. Unlike in cities, the tropospheric delay is significant between two PSs with even a small horizontal separation but with a large height difference. To construct a better network, not only the horizontal separation between PSs but also the height difference must be considered. The topographic dependent phase component could be integrated into the estimation system which was based on the STUN algorithm [7]. This research is a part of the German volcano monitoring project Exupèry, Work Package 2: ‘Space based observation techniques’ [8].