The island of Majorca (Spain), located in the western Mediterranean, has a variety of different geomorphological domains, most prominently the Tramuntana Range (1,100 km2) in the north-western part of the island. The steep topography of this chain, which is linked to its geological complexity and Mediterranean climate, determines intense slope dynamics with the consequent movements of all categories. The main income of the island of Majorca comes from tourism (83% of its GDP), as it welcomes 10 million visitors each year. The urban development that the Tramuntana region has undergone in the past 30 years has considerably increased the risk originating from mass movements.
Practically all the slope movements recorded on Majorca have taken place in the Tramuntana Range. The variety of lithologies cropping out in this mountain chain determines a wide range of slope movements. Landslides and earth flows are frequent phenomena, primarily affecting soft sediments from the Late Triassic (Keuper), made up of clays with gypsum, as well as an entire series of loamy materials from the Palaeogene and Neogene that occasionally outcrop along the mountain range. The most prominent movements include the Fornalutx landslide which took place on the 17 December 1924, affecting an area of around 150,000 m2. However, the most important mass movement in the Balearic Islands, because of both its dimensions and the damage it caused, was the Biniarroi landslide in spring 1721, with later local reactivations in 1816, 1857 and 1943. This landslide affected an area measuring around 300,000 m2 and totally modified the original topography in the region.
Rockfalls are the most frequent slope movements in the Tramuntana Range due to the predominance of Jurassic rocky massifs made up of limestone and dolostone. Historically, there are records of several major rockfalls. On the 16 March 1857, a huge rockfall on the Valldemossa area razed and buried a large extension of cropland, leaving reports in the daily news. More recently, numerous rockfalls have made the news as well, such as the one in Cala de Banyalbufar (1993), which affected several fishing huts and the rockfall in Son Matge (Valldemossa) in 2005, in which one of the most important archaeological sites from Majorca's prehistory was buried. The main traffic arteries in the mountain range, both road and rail, have often been intercepted by slope movements, triggering serious circulation problems as well as major economic losses. The historical compilation of the slope movements on the island, as well as the record of those that have occurred more recently, reveal that all processes have taken place after short-intense and/or continuous rainfall. Between 2008 and 2010, the island of Majorca 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 /24 h were recorded. Additionally, high precipitation coincided with anomalous, low temperatures and freezing in the highest zones of the Tramuntana range. As a result, 34 mass movements were recorded: 14 rockfalls, 1 rock avalanche, 15 landslides and 4 karstic collapses. Fortunately, there were no deaths but there were numerous cases of damage to dwellings, holiday apartment blocks, barns and power stations, and especially the road network in the range, most significantly the numerous blockages on the Ma-10 road, which caused significant economic losses in the different tourist resorts. On the southern coast of the range, 17 holiday homes have been evacuated recently due to the impending risk of a large rockfall. Total economic losses are valued at approximately 11M Euro, which represents 0.042% of the Balearic Autonomous Region GDP.
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