Advanced SAR Interferometric Analysis to Support Geomorphological Interpretation of Slow-Moving Coastal Landslides (Malta, Mediterranean Sea)

Matteo Mantovani,Stefano Devoto,Daniela Piacentini,Mariacristina Prampolini,Alessandro Pasuto,Mauro Soldati

doi:10.3390/rs8060443

Abstract

An advanced SAR interferometric analysis has been combined with a methodology for the automatic classification of radar reflectors phase histories to interpret slope-failure kinematics and trend of displacements of slow-moving landslides. To accomplish this goal, the large dataset of radar images, acquired in more than 20 years by the two European Space Agency (ESA) missions ERS-1/2 and ENVISAT, was exploited. The analysis was performed over the northern sector of Island of Malta (central Mediterranean Sea), where extensive landslides occur. The study was assisted by field surveys and with the analysis of existing thematic maps and landslide inventories. The outcomes allowed definition of a model capable of describing the geomorphological evolution of slow-moving landslides, providing a key for interpreting such phenomena that, due to their slowness, are usually scarcely investigated.

Highlights

The use of interferometric methods to infer earth surface deformation from satellite-borne synthetic aperture radar has become a regular tool in geoscience since the early 1990s [1]
The displaced limestone blocks over the clayey slopes of the north-western coast of Malta can reflectorsbecan be found in built environments, since walls and roofs can consistently backscatter the considered suitable reflectors, as it can be noticed by the large amounts of point target candidates radar signal time
Interferometric methods have been often used to measure surface displacements caused by mass movements, but in this study Interferometric Point Target Analysis (IPTA) processing and a modified version of PSTime algorithm were coupled in order to provide more relevant information

Summary

Introduction

The use of interferometric methods to infer earth surface deformation from satellite-borne synthetic aperture radar has become a regular tool in geoscience since the early 1990s [1]. Sporadic/intermittent movements can be measured, e.g., displacements higher than 1 cm occurring during major earthquakes, deformations in volcanic areas and other kinds of episodic motion [2]. Non-episodic motions can be surveyed by combining long series of radar acquisitions it is possible to measure, for example, the rate of subsidence due to mining [3], to ground-water extraction [4] or to slow-moving landsliding [5,6,7]. The algorithms that are nowadays used to monitor and measure long-term evolution of ground deformation descend from two types of approach: the Short BAseline. Subsets (SBAS) proposed by [8], and the PSI (Persistent Scatterer Interferometry) developed by [9].

Methods

Results

Discussion

Conclusion