Freeze-thaw cycles and rainfall as triggering factors of mass movements in a warm Mediterranean region: the case of the Tramuntana Range (Majorca, Spain) Abstract Between 2008 and 2010, the island of Majorca (Spain) experienced the coldest and wettest winters of the last 40 years. Accumulated rainfall was twice the average and values of intense rainfall up to 296 mm/24h were recorded, very similar to those calculated for a return period of 100 years. Additionally, high precipitation coincided with anomalous, low temperatures, with abundant snowfall and freezing in the highest zones of the Tramuntana Range, in the northwest sector of the island. As a result, 34 mass movements were recorded on the range, which seriously affected the road network in an area of great importance for tourism, as it welcomes 8.5 million visitors each year. Fourteen rockfalls, 1 rock avalanche, 15 landslides and 4 karstic collapses were inventoried. The geological structure, formed by a series of NW overlapping thrusts, determines the distribution as well as the failure pattern of the movements. Thus, the northern face of the range registered 68% of the mass movements: nine rockfalls with planar failure took place as well as all the landslides recorded. Likewise, south-facing slopes have been affected by longer runout rockfalls with a wedge-type failure. The thorough analysis of the meteorological data shows that most of the movements have taken place after antecedent rainfall over 800mm. Additionally, the rockfalls have also occurred after several freeze-thaw cycles, being a determining and unusual factor in this warm region. Intense rainfall >90 mm/24h also caused rockfalls as well as exceptional very intense rainfall >120 mm/24h caused landslides. The results aim to contribute to the design of an early warning system coordinating emergency, infrastructure services and meteorological centres in a region of high risk.

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In the present work, spectral analysis has been applied to determine the presence and statistical significance of climate cycles in long-term data series from different rainfall and gauging stations located in the Tramuntana Range, in the north-western sector of the island of Majorca. Climate signals recorded previously in the Mediterranean region have been identified: the ENSO, NAO, HALE, QBO and Sun Spot cycles as well as others related to solar activity; the most powerful signals correspond to the annual cycle, followed by the 6-month and NAO cycles. The incorporation of data derived from gauging stations contributes to better climate signal detection as local and exceptional influences are eliminated. Simulations have been performed for each rainfall/gauging station, using the most significant climate cycles obtained by means of the power spectrum. A good correlation between rainfall/flow values and simulated cycles has been obtained. The NAO and ENSO cycles are the most influential in the rainy periods, and specifically the NAO cycle, where a good correlation between episodes of high rainfall/flow and high values of ANAOI can be observed. At a second stage, landslides dated and recorded in the Tramuntana Range since 1954 (174 events) have been correlated with the simulated cycles obtaining good results, as the landslide events match rainfall peaks well. The correlation for the past decade (since 2005), when a detailed landslide inventory is available, also

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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.