INSTRUMENTATION SYSTEM FOR IN SITU MONITORING OF GROUND DEFORMATION IN IZTAPALAPA, MEXICO CITY
Based on the fracture analysis we have designed a measurement system of surface deformation distributed on the Iztapalapa area. The system includes: monitoring sites of surface deformation (EMDS, Estacion de Monitoreo de Deformacion Superficial), an optical array of monitoring (SODS, Sistema Óptico de Deformación Superficial), and a network of georeferred leveling sites. Five EMDS have been placed during 2011 in fractured sites, which include mechanical instruments using either a micrometer to measure moderate displacements in vertical and horizontal directions (3D); and an angular instrument that consists of a lever arm of 5 m in length with an angle amplifier (1D). Continuous measurement of the deformation generate reliable information to correlate deformation with geological and/or anthropogenic triggering mechanisms. The SODS is a recent technological development, robust and low cost, used to monitor widespread deformation in approximately 2500 m2 areas that includes a programmed camera, two laser devices and a mirror to asses 3D deformation with a milimetric resolution.
The in situ monitoring system are being complemented with remote sensing studies and topographic leveling in selected sites in order to asses the local and regional deformation processes. Iztapalapa is the first entity in Mexico with a deformation monitoring system, the continuous measurements will support the diagnosis of stability of the subsoil to establish mitigation measures or preventive actions at different scales.