The deformation pattern of the 6 and 7 April 2009 M_W=6.3 and M_W=5.6 earthquakes in L'Aquila is revealed by DInSAR analysis and compared with earthquake environmental effects. The DInSAR predicted fault surface ruptures coincide with localities where surface ruptures have been observed in the field, confirming that the ruptures observed near Paganica village are indeed primary. These ruptures are almost one order of magnitude lower than the ruptures that have been produced by other major surrounding faults in the past. These faults have not been activated during the 2009 event, but have the capacity to generate significantly stronger events. DInSAR analysis shows that 66% (or 305 km²) of the area deformed has been subsided whereas the remaining 34% (or 155 km²) has been uplifted. A footwall uplift versus hangingwall subsidence ratio of about 1/3 is extracted from the mainshock. The maximum subsidence (25 cm) was recorded about 4.5 km away from the primary surface ruptures and about 9 km away from the epicentre. In the immediate hangingwall, subsidence did not exceeded 15 cm, showing that the maximum subsidence is not recorded near the ruptured fault trace, but closer to the hangingwall centre. The deformation pattern is asymmetrical expanding significantly towards the southeast. A part of this asymmetry can be attributed to the contribution of the 7 April event in the deformation field.

A discrete scattering model, based on the radiative-transfer theory, is used to simulate the backscattering of burned pine canopies at C-band. The model is first parameterized either with direct field measurements on a selected burned area in Greece or with proper estimations of the required variables, for which direct measurements were not possible. The simulated backscatter at VV polarization was compared against European Remote Sensing 2 (ERS-2) observations. The comparison was based on the observed backscattering of nine burned plots, during four different postfire acquisitions (n=36). In general, the model provides satisfying estimations of the backscattering with a root-mean-square error of 1.01 dB. The copolar signal for both HH and VV showed a mild decrease with increasing fire impacts and was considerably affected by the incidence angle. From the experiments performed in the simulated environment, it is concluded that the SAR copolar (C-band) backscatter varies with respect to certain fire impact levels. Other important acquisition- or stand-dependent variables (such as incidence angle and snag age) were also found to impact the relationship between backscatter and fire impacts. Finally, the backscattering variability on increasing volumetric soil moisture (VSM) and snag moisture was examined. The increase of VSM from 20% to 30% amplified the signal in both copolarized bands by 1.2-1.5 dB. This amplification was more apparent on VV polarization than in HH polarization. Instead, the HH signal proved to be more sensitive on the increase of snag moisture, which was tested under a stable dry soil.

Since its last eruption in 1950, Santorini volcano (Greece) remained in a dormant state. This is also evidenced for the period 1992–2010 by the gradual deflation signal over Nea Kameni as measured by satellite Synthetic Aperture Radar Interferometry (InSAR) with low rates of about 5–6 mm yr^–1 as well as by the absence of seismic activity within the caldera. However, at the beginning of 2011 the volcano showed signs of unrest with increased microseismic activity and significant ground uplift, reaching 14 cm within a year (2011 March–2012 March), according to InSAR time-series. ALOS PALSAR data indicate the onset of the phenomenon in early 2010 where an aseismic pre-unrest phase of increased subsidence (1–3 cm) preceded the uplift. Joint inversions of SAR and GPS velocities using spherical and spheroidal magmatic source types indicate their location offshore at about 1 km north of Nea Kameni and between 3.5 and 3.8 km depth. The estimated volume variation rate is 6 × 10⁶ m³ yr^-1 to 9 × 10⁶ m³ yr^-1. A gradual slowing in the rate of inflation within the first quarter of 2012 is apparent by ENVISAT data, while subsequent observations from RADARSAT-2 confirm the observed trend.

Monitoring of active faults in urban areas is of great importance, providing useful information to assess seismic hazards and risks. The present study concerns the monitoring of the potential ground deformation caused by the active tectonism in the cities of Patras and Pyrgos in Western Greece. A PS interferometric analysis technique was applied using a rich data–set of ERS–1 & 2 SLC images. The results of the interferometric analysis were compared with the tectonic maps of the two cities. Patras show clearer uplift–subsidence results due to the more distinct fault pattern and intense deformation compared to the Pyrgos area, where more diffused deformation is observed, with no significant displacements on the surface.

Spaceborne Multi-Temporal Synthetic Aperture Radar (SAR) Interferometry (MT-InSAR) has been a valuable tool in mapping motion phenomena in different scenarios. Recently, the capabilities of MT-InSAR for risk monitoring and preventive analysis of heritage sites have increasingly been exploited. Considering the limitations of conventional MT-InSAR techniques, in this study a two-step Tomography-based Persistent Scatterers (PS) Interferometry (Tomo-PSInSAR) approach is proposed for monitoring ground deformation and structural instabilities over the Ancient City Walls (Ming Dynasty) in Nanjing city, China. For the purpose of this study we utilized 26 Stripmap acquisitions from TerraSAR-X and TanDEM-X missions, spanning from May 2013 to February 2015. As a first step, regional-scale surface deformation rates on single PSs were derived (ranging from −40 to +5 mm/year) and used for identifying deformation hotspots as well as for the investigation of a potential correlation between urbanization and the occurrence of surface subsidence. As a second step, structural instability parameters of ancient walls (linear motion rates, non-linear motions and material thermodynamics) were estimated by an extended four-dimensional Tomo-PSInSAR model. The model applies a two-tier network strategy; that is, the detection of most reliable single PSs in the first-tier Delaunay triangulation network followed by the detection of remaining single PSs and double PSs on the second-tier local star network referring to single SPs extracted in the first-tier network. Consequently, a preliminary phase calibration relevant to the Atmospheric Phase Screen (APS) is not needed. Motion heterogeneities in the spatial domain, either caused by thermal kinetics or displacement trends, were also considered. This study underlines the potential of the proposed Tomo-PSInSAR solution for the monitoring and conservation of cultural heritage sites. The proposed approach offers a quantitative indicator to local authorities and planners for assessing potential damages as well as for the design of remediation activities.