Spatio-temporal analysis of the role of climate cycles on landslide activity: the case of Majorca (Spain)

Abstract

Abstract. Intense precipitation is one of the main drivers of landslides around the globe. On a global scale, the occurrence of very wet periods is controlled by different, well-known natural cycles: ENSO, NAO, SUNSPOT, etc. In this paper, we present a spatio-temporal analysis of climate cycles on the island of Majorca (Spain) and their correlation with the landslide inventory. Firstly, using spectral analysis techniques, the main climatic cycles that control the rainy periods on the island have been identified. For this purpose, rainfall data from 62 weather stations have been analysed in a comprehensive manner, with time series of more than 30 years. The cycles with the greatest influence on rainfall, from the point of view of statistical confidence, are ENSO (5.6 y and 3.5 y), as well as NAO (7.5 y) and QBO. Then, using geostatistical methods, the distribution of rainfall during dry, average, and wet years was mapped, as was the spatial representation of the statistical significance of the different natural cycles, in order to define the areas of greatest danger from heavy rainfall. The Serra de Tramuntana is not only the rainiest region of the island, but also the area where the highest values of statistical confidence for the set of climatic cycles are concentrated. The 5 largest landslides of the series are very well located in the areas of highest statistical weight, mainly for the NAO (7.5 y), QBO and HALO (22.4 y) cycles, as well as in the wettest sector for the wet type year.