The Pico de Navas slump (Burgos, Spain): a large rocky landslide caused by underlying clayey sand fluidification

The Pico de Navas landslide was a large-magnitude rotational movement, affecting 50x106m3 of hard to soft rocks. The objectives of this study were: (1) to characterize the landslide in terms of geology, geomorphological features and geotechnical parameters; and (2) to obtain an adequate geomechanical model to comprehensively explain its rupture, considering topographic, hydro-geological and geomechanical conditions. The rupture surface crossed, from top to bottom: (a) more than 200 m of limestone and clay units of the Upper Cretaceous, affected by faults; and (b) the Albian unit of Utrillas facies composed of silty sand with clay (Kaolinite) of the Lower Cretaceous. This sand played an important role in the basal failure of the slide due to the influence of fine particles (silt and clay), which comprised on average more than 70% of the sand, and the high content presence of kaolinite (>40%) in some beds. Its geotechnical parameters are: unit weight (δ) = 19-23 KN/m3; friction angle (φ) = 13º-38º and cohesion (c) = 10-48 KN/m2. Its microstructure consists of accumulations of kaolinite crystals stuck to terrigenous grains, making clayey peds. We hypothesize that the presence of these aggregates was the internal cause of fluidification of this layer once wet. Besides the faulted structure of the massif, other conditioning factors of the movement were: the large load of the upper limestone layers; high water table levels; high water pore pressure; and the loss of strength due to wet conditions. The 3D simulation of the stability conditions concurs with our hypothesis. The landslide occurred in the Recent or Middle Holocene, certainly before at least 500 BC and possibly during a wet climate period. Today, it appears to be inactive. This study helps to understand the frequent slope instabilities all along the Iberian Range when facies Utrillas is present.

Ecuadorian migration and family strategies of social mobility: dialectic relation between emotional and financial capital

This text deals with transnational strategies of social mobility in Ecuadorian migrant households in Spain. We apply the capital accumulation model (Moser, 2009) for this purpose. The main target of this article is, beyond thinking in terms of capital stock and accumulation, the analysis in depth of the dynamics of the different types of capital, that is to say, how they interact with each other in the framework of the social mobility strategies of the migrants and their families. We are bringing into light the way some households adopt investing decisions in capitals that don't translate into any addition or earnings in all cases, on the contrary, concentrating all their efforts on the accumulation of a certain asset they may, in some cases, lead to a loss of another. We will concentrate our analysis primarily on the dynamics between the physical and financial capital and the social and emotional capital, showing the tensions produced between these two types of assets. At the same time, we will highlight how migrants negotiate their family strategies of social mobility in the transnational area. Our study is based in empirical material obtained from qualitative fieldwork (in-depth interviews) with families of migrants in the urban district of Turubamba Bajo -(south of Quito) and in Madrid. A series of households were selected where interviews were carried out in the country of origin as well as in the context of immigration, with different family members, analysing the transnational social and economic strategies of families of migrant members. Family members of migrants established in Spain were interviewed in Quito, as well as key informants in the district (school teachers, nursery members of the staff, etc.). The research was framed within the projects "Impact of migration on the development: gender and transnationalism", Ministry of Science and Innovation (SEJ2007/63179) (Laura Oso, dir. 2007-2010),"Gender, transnationalism and intergenerational strategies of social mobility", Ministry of Economy and Competitiveness (FEM2011/26210) (Laura Oso, dir. 201-1-2015) and “Gender, Crossed Mobilities and Transnational Dynamics”, Ministry of Economy and Competitiveness (FEM2015-67164).