The housing deficit, which affects especially the most vulnerable sectors, corresponds to a constant and growing challenge for housing policies developed in the Chilean context. Its provision presents complexities that respond, to a large extent, to the availability and high values of land as a result of market deregulation. The demand for new housing, in this sense, has been resolved under two mechanisms: through irregular land occupations and self-construction of housing, and through state action and the implementation of programmatic devices for the construction of new residential complexes. Housing developments or settlements are generally located on the margins of urbanized territory—that is, in sectors where land transaction costs are lower due, in part, to possible conditions of risk or territorial vulnerability. These conditions are strongly expressed in the housing configuration and spatial location patterns that characterize the commune of Alto Hospicio, located in the Tarapacá Region in northern Chile. In this commune, whether due to the spontaneous action of the inhabitants or the action of state institutions, housing intended for socially vulnerable sectors is exposed to conditions that can lead to significant losses of residential assets and affect the living conditions of their inhabitants.
Article
Housing Deficit and Disaster Risk Management in Chile
Natalia Ponce Arancibia
Article
Sinkhole Hazards
Francisco Gutiérrez
Sinkholes or dolines are closed depressions characteristic of terrains underlain by soluble rocks (carbonates and/or evaporites). They may be related to the differential dissolutional lowering of the ground surface (solution sinkholes) or to subsidence induced by subsurface karstification (subsidence sinkholes). Three main subsidence mechanisms may operate individually or in combination: collapse, sagging, and suffosion. Subsidence sinkholes may cause severe damage to human built structures, and the occurrence of catastrophic collapse sinkholes may lead to the loss of human life. Dissolution and subsidence processes involved in the development of subsidence sinkholes are controlled by a wide range of natural and anthropogenic factors. Recent literature reviews reveal that the vast majority of the damaging sinkholes are induced by human activities (e.g., water table decline, water input to the ground). The main steps in sinkhole hazard and risk assessment include: (a) construction of comprehensive sinkhole inventories and detailed sinkhole characterization; (b) development of independently tested sinkhole susceptibility and hazard models, preferably incorporating magnitude and frequency relationships; (c) assessing risk combining hazard and vulnerability data. Sinkhole risk models may be used as the basis to perform cost-benefit analyses that allow the cost-effectiveness of different mitigation strategies to be estimated. Three main concepts may be applied to reduce sinkhole risk: (a) avoiding sinkholes and sinkhole-prone areas (preventive planning); (b) diminishing the activity of dissolution and/or subsidence processes (hazard reduction); (c) incorporating special designs in the structures (vulnerability reduction). Although our capabilities to investigate sinkhole hazards and reduce the associated risks will continue to increase in the near future, the damage related to sinkholes will also increase, largely due to the adverse changes caused by human activities on the karst environments and the ineffective knowledge transfer between scientists, technicians, and decision-makers. This article presents the processes and factors involved in sinkhole development and reviews the main approaches used to assess and manage sinkhole hazards and risks.
