Coastal lateral spreading in the world heritage site of the Tramuntana Range (Majorca, Spain). The use of PSInSAR monitoring to identify vulnerability

Abstract

Coastal lateral spreading in the world heritage site of the Tramuntana Range (Majorca, Spain). The use of PSInSAR monitoring to identify vulnerability Abstract The Bàlitx area is located on the steep coastal side of the Tramuntana Range (Majorca), a mountainous region which was declared a World Heritage Site by UNESCO in 2011 in the cultural landscape category. The Bàlitx site was occupied by farming areas with dry stone constructions and water storing systems of both Roman and Islamic origin. The coastal landscape is characterised by a large fault escarpment of up to 260 m in height. Lateral spreading processes are favoured by local stratigraphy and tectonics in an energetic coastal dynamics scenario. Block spreading morphologies are identified along the escarpment, with large, rocky blocks of volumes up to 60 × 10 3 m 3 moving very slowly until their collapse. Consequently, a thick and highly karstified breccia deposit is accumulated at the base of the scarp. The lowest, oldest breccia outcrop has been dated (Th/U), and an age of 82.5 ± 5.6 kyr was obtained, reflecting the time span this process has been active. Additionally, numerous geomorphological slope features are identified in the area: landslides, rockfalls, and, more specifically, long and deep cracks in the hanging wall block of the fault, which also reveal active lateral spreading processes. Coastal dynamics have been investigated by interpreting offshore geophysical studies, bathymetry data and borehole information to determine the role of wave energy in the stability of the slope. Additionally, 14 SAR images from the ALOS PALSAR satellite have been exploited for the present work, covering a period spanning from 2007 to 2010, an anomalous rainy period in the region. Images were processed using the Persistent Scattered Interferometry (PSI) technique. PSInSAR results reveal that the rate of movement for the Bàlitx lateral spreading is extremely low (− 5.2 mm/ year on average), but major activity has been detected in the NE sector, where velocity rates can reach values of up to − 16 mm/year Coastal dynamics in the area can explain this, as a small island generates wave refraction and reflection determining more intense erosive processes in the NE part, which lead to a greater destabilising effect on the slopes. A simple vulnerability approach has been developed to take the elements of cultural heritage into account. Vulnerability increases from SW to NE, in accordance with landslide activity. The Bàlitx case study could provide a testimony to the effects of mass movements and coastal dynamics in an exceptional example of Mediterranean agricultural landscape.

Analysis of the Geological Controls and Kinematics of the Chgega Landslide (Mateur, Tunisia) Exploiting Photogrammetry and InSAR Technologies

“…Delgado et al [63] measured by InSAR rates resembling that of Chgega (2-4 mm/yr) in a compound rotational DGSD of large dimensions in the Sierra de Aitana (Spain). Mateos et al [17] reported an average velocity of the same order of magnitude (5.2 mm/yr) in a large lateral spreading along the North coast of Majorca (Spain). Extensive lateral spreading and block sliding processes in a geological setting comparable to the Chgega landslide have been under investigation since 2006 in the North part of Malta [8,9,[64][65][66].…”

“…Our description of Chgega Mountain has benefited from new data gathered through up-to-date remote sensing (RS) techniques: landscape analysis, Uncrewed Aerial Vehicle Digital Photogrammetry (UAV-DP), and advanced Satellite InSAR techniques. The combination of the two latter techniques has already proven its usefulness for landslide characterization elsewhere (see for example the studies of Cigna et al [16] in Ireland, Mateos et al [17] in Spain, or Hopffer Martins et al [18] in Timor-Leste). The focus here, in turn, is on a region where RS methods are not yet common.…”

Effects of Wildfire on Rockfall Occurrence: A Review through Actual Cases in Spain

“…The landscape is marked by agricultural terraces constructed in dry stone to extend farmland. The terraces have also played an important role in preventing damage from soil erosion and very frequent slope movements [125]. Pine and holm oaks forest and a rich shrub layer mainly cover the range.…”

Advantages of Using UAV Digital Photogrammetry in the Study of Slow-Moving Coastal Landslides

“…In particular, landslides are common along the European coasts of the Mediterranean Sea and can include different types of transport mechanisms such as falls, slides, spreads, or flows [9][10][11][12][13][14]. Among these, lateral spreading and block sliding processes are widely represented in the Mediterranean coasts, such as in northern Mallorca (Spain) [15], in the western part of Liguria (Northern Italy) [16], Tropea area (Southern Italy) [17], Scopello in northern Sicily [18] and in the Maltese islands [14,19,20].…”