Monitoring tectonic-, seismic- and landslide-related ground deformation with radar Interferometry : Al Hoceima case study in northern Rif (Morocco)

Project leaders

Eugenio Sansosti, Hassan Tabyaoui

Agreement

MAROCCO - CNRST - Centre National pour la Recherche Scientifique et Technique

Call

CNR/CNRST biennio 2018-2019 2018-2019

Department

Earth system science and environmental technologies

Thematic area

Earth system science and environmental technologies

Status of the project

New

Research proposal

The Al Hoceima region is situated in Morocco on the Mediterranean Coast of the Rif Mountain. The latter extends to the Betic Mountains in southern Spain and constitutes the westernmost edge of the Alpine Orogeny. The area is known by its complex tectonic history as a result of the African and European plate convergence. The present-day convergence rate, determined from GPS data, is 5.5 mm/yr in the WNW-ESE direction. This causes ground movements (e.g. landslides) and seismic activities. Two large earthquakes have occurred in the past 11 yrs. On May 26, 1994, a Mw 6.0 earthquake caused significant damages and two deaths. On February 24, 2004, a Mw 6.5 earthquake caused over 600 fatalities with 40 000 made homeless. These earthquakes are the largest occurred in Morocco in 100 yr, and give valuable insight into the poorly understood tectonics of this area.

Landslides can be associated with seismic activity. Moreover, minor and localized movements of earth surface often precede landslides. Landslides can cause human injury, loss of life and economic devastation, and destroy construction works and cultural and natural heritage. The impact of these natural disasters can be reduced or prevented by performing a proper detection and measurement of such ground movements.

The main result of this work will be to detect movements occurring before a landslide. Interferometric techniques represent a powerful tool for identifying most of the unstable points in urban and natural areas and to deduce values of displacement velocities and time series.

Usage of satellite image processing for ground movement monitoring is emerging as a new applied research domain due to the great cost-benefits ratio, acquisition policy, good attitude and high orbit stability of the satellite platform, non-invasiveness and high precision of remote sensing techniques, and increasingly high resolution of radar sensors. Moreover, satellite radar interferometry allows, at least in principle, ground measurement coverage over the past 25 years, thanks to the present and past satellite sensors.

For radar data processing, we will rely on the use of the image processing algorithms developed by Italian team over the past 20 years. In particular, we will generate ground deformation time series and velocity maps based on the well-known SBAS algorithm [Berardino et al., 2002]. When needed, a full resolution deformation analysis [Fornaro et al., 2015] will be also carried out. This can be particularly useful while analyzing small landslides with very subtle movements as it can also improve detection and measurement of movements on the landslide planes not favorably oriented with respect to the radar line of sight.

Data from the following satellites will be considered for this project. C-band sensors such as ERS-1 (1991-2000), ERS-2 (1995-2011) and ENVISAT (2002-2012), which can give insights on the deformation occurred in the past, including the two largest earthquakes in 1994 and 2004. Contemporary data from C-band Sentinel-1 satellites (1a operating since 2014 and 1b since 2016), along with X-band TerraSAR-X satellites (since 2008) and COSMO-SkyMed (CSK) constellation (CSK-1 and CSK-2 launched in 2007, CSK-3 in 2008 and CSK-4 in 2010). In particular, X-band sensors can provide data for higher resolution analyses. The detailed selection of data to be used will be defined during the first months of the project.

The outcomes of this work are a series of maps representing valuable examples of detection and characterization of landslide-induced phenomena identified in detail by radar interferometry at local scale. This approach will provide insights for the implementation of best strategies for risk mitigation and urban-environmental design. Results are important for land management department, securities agencies and national ministries.

In Al Hoceima, landslides present a major threat to property, infrastructure and natural environment. In this mountainous area of the Rif chain, most landslides are located along major rivers (Oued Mansour, Oued Ajdir, Oued Isli) and along the Mediterranean coast (at Tala Youssef, Quemado). The socio-economic impact from landslides is generally underestimated and numbers vary as landslide events are usually not separated from other natural hazards such as floods and earthquakes.

The presented project will demonstrate the increasing important role played by radar interferometry in ground movement management in Al Hoceima region. The application will be finalized to define the landslide dynamic and to evaluate possible risk scenarios.

To our knowledge, it will be the first time that this type of radar remote sensing technique for ground movement detection will be used in Morocco. A possible future application of the results of this project can be the use of this technique to monitor slide movements impacting road networks in the Rif Mountain.

This project will start-up a community of scientific researchers with deep competencies in radar remote sensing in Morocco. For this project, two researchers and 1 PhD student from the Moroccan part and 4 researcher staff members form the Italian side will participate to the research for a total period of 24 months.

References
P. Berardino, G. Fornaro, R. Lanari and E. Sansosti, "A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms," IEEE Transactions on Geoscience and Remote Sensing, vol. 40, no. 11, pp. 2375-2383, Nov 2002, doi: 10.1109/TGRS.2002.803792

G. Fornaro, S. Verde, D. Reale and A. Pauciullo, "CAESAR: An Approach Based on Covariance Matrix Decomposition to Improve Multibaseline-Multitemporal Interferometric SAR Processing," IEEE Transactions on Geoscience and Remote Sensing, vol. 53, no. 4, pp. 2050-2065, April 2015, doi: 10.1109/TGRS.2014.2352853

Research goals

Al Hoceima region (Morocco) is located on the Mediterranean Coast of the Rif Mountain, an area characterized by a complex tectonic history resulting from the African and European plate convergence. The two largest earthquakes in Morocco in 100 years occurred in this area on May 26, 1994 (Mw 6.0) and on February 24, 2004 (Mw 6.5) earthquake, the latter causing over 600 fatalities.

One objective of this project is to detect and measure the land displacements associated with neotectonics by using satellite radar remote sensing in order to give valuable insight into the poorly understood tectonics of this area.

Furthermore, landslides are often associated with seismic activity, with subtle and localized movements of earth surface often being precursors. In Al Hoceima, landslides present a major threat to property, infrastructure and natural environment. Accordingly, a further objective of the project is to detect and measure ground movements associated with landslides. This activity will be finalized to define the landslide dynamic and to evaluate possible risk scenarios.

The study will determine, for the first time, whether the emerging technology of satellite radar remote sensing allows detecting and measuring ground movement in Al Hoceima. Depending on the ground deformation characteristics, an appropriate selection of the radar sensors and processing strategies will be carried out.

Last update: 15/09/2024