Modelo morfométrico de la avalancha rocosa de Arteara, Gran Canaria

Abstract

The extensive scree of Arteara covers a translational slide. Geological-geotechnical characterization has been the subject of previous studies. This work includes the morphometric analysis of a DEM, the PNOA orthophoto and several field surveys. The volume of the deposit was obtained by difference of MDE from 86 profiles. 476 blocks larger than 2m were mapped. 4 kinds of blocks were differentiated: 318 (8-27m³); 118 (27-64m³); 32 (64-125m³); 8 (>125m³). The heigth of the larger blocks (>3m) was mesured. The prototype profiles were defined, as well as the main morphometric parameters of the rock avalanche were extracted. From the block mapping, the percentage of block accumulation and the spatial distribution were obtained, according to block sizes. The heat map analysis shows the existence of 3 accumulation type zones (head, foot and flanks). The highest acumulation is located in the heat and then in the foot. In the header, 130 blocks define several parallel levees and are distributed asymmetrically, conditioned by the slope orientation of the pre-existing relief. In the foot zone, 90 blocks are grouped defining a single levee along the perimeter contour. On the flanks there are 2 small overflows, associated with topographic declines and a marginal source area, associated with the progressive destabilization of a large dismembered block of the main escarpment. The block map analysis confirmed that the large blocks (>64m³) are observed in the areas of greatest accumulation. The multimodal distribution of the blocks and the preservation of levee morphologies in the foot and at the head of the rock avalanche deposit suggests a multi-stage morphogenesis with a progressive reduction of the kinetic energy of the process, wich results in current relief.