Subsidence and associated shallow faulting hazard assessment in central Mexico using InSAR and GPS

Thursday, 18 December 2014
Enrique Cabral-Cano1, Dario E Solano Rojas2, Talib Oliver-Cabrera2, Luis Salazar-Tlaczani1, Shimon Wdowinski3, Charles DeMets4 and Jesus Pacheco5, (1)Universidad Nacional, Autónoma de México, Departamento de Geomagnetismo y Exploración, Instituto de Geofísica, Mexico, DF, Mexico, (2)University of Miami, Miami, FL, United States, (3)University of Miami, Marine Geology and Geophysics, Miami, FL, United States, (4)University of Wisconsin Madison, Madison, WI, United States, (5)Universidad Autónoma de Aguascalientes, Departamento de Construcción y Estructuras, Aguascalientes, Mexico
While subsidence has affected Mexico City for over a century, other cities in central Mexico have been subjected to subsidence since the '80, as a result of their large urban expansion, population increase and aggressive groundwater extraction rates. The continuous subsidence results in severe damage to urban infrastructure and civil structures. Unfortunately the damage cost assessment and vulnerability are difficult to evaluate, because of the variable geographic extent and the continuous nature of the process, which have different characteristics than localized, short duration hazards, as earthquakes or flood events.We have monitored land subsidence in 17 cities in central Mexico using both InSAR and GPS observations. InSAR provides an unsurpassed synoptic view of the earth's dynamic surface. However, different satellite sensors and sometimes widely spaced data availability make it difficult to derive long-term time series, rapid changes or nonlinear variations of subsidence velocities. To alleviate this situation, higher temporal resolution subsidence observations of associated fault motion has been pursued using continuously operating GPS stations. We have developed a GPS network that covers 6 urban centers to detect short duration variations using different processing schemes that include both real-time solutions using RTNet as well as daily solution using Gipsy-Oasis.Cartographic products based on these techniques have been merged with other population, hydrology and meteorology data sets. This approach allows a better hazard assessment and provides information for other purposes, such as vulnerability for shallow faulting, land use zonations, and other decision elements for water resource management agencies. We will provide examples of these hazard assessments for several cities, including Mexico City, Aguascalientes, Morelia, Irapuato and Celaya and the challenges encountered to integrate these results with other data sets from federal and state organizations.