Satellite geodesy tools for ground subsidence and associated shallow faulting hazard assessment in central Mexico

Abstract

MotivationWhile subsidence has affected Mexico City for over a century, other cities in central Mexico have been subjected to ground subsidence since the 1980's, as a result of their large urban expansion, population increase and aggressive groundwater extraction rates. The continuous ground 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 time-continuous nature of the process, which have different characteristics than other phenomena characterized by localized, short duration events such as earthquakes or floodings with better media coverage.A recent SBAS survey based on ALOS-1 PALSAR data along central Mexico (Chaussard et al., 2014) indicates that this process is rapidly becoming a widespread phenomenon that potentially affects a population over 25 million inhabitants. InSAR-derived information and its cartographic products from geodetic imaging will be key to develop a better groundwater extraction strategy in areas that undergo extreme subsidence rates, propose better mitigation strategies and ultimately improve water resource management.In Mexico, subsidence induced damage to houses or other urban infrastructure is not eligible for federal emergency relief funds, because it is not considered a naturally occurring process but rather an anthropogenically induced one. Furthermore, this phenomenon is localized and usually managed only at the local city or county-level administrations, while most other large impact natural hazards, as earthquakes, volcano eruptions, or flooding events, are usually managed by federal agencies. This work is aimed towards a better recognition of subsidence as a major hazard in Mexico, assess the number of inhabitants affected and the spatial extent of the subsiding areas affected by this process. The space-based subsidence imaging can be used to improve water resources management (e.g. Hernández-Espriú et al., 2014) in an area that comprises a number of rapidly growing urban areas and assess its associated surface faulting geological hazard.We envision that this work will serve as a test case where water-usage policy makers can have access to custom cartographic products suitable for data fusion and data mining from third party regional water management agencies databases and include satellite geodesy imaging techniques as a routine monitoring technique for aquifer assessment and its sustainable management. Within this context, space geodetic techniques, most notably InSAR complemented by GPS are quite suitable for this task. InSAR provides an unsurpassed synoptic view of the earth's dynamic surface; for Published by Copernicus Publications on behalf of the International Association of Hydrological Sciences.

Application of InSAR and Gravimetry for Land Subsidence Hazard Zoning in Aguascalientes, Mexico

“…Some authors have proposed solutions for determining the zones prone to develop subsidence-related ground faulting [15,23,27,32,33]. These methodologies are based on the determination of the horizontal gradients of a measured parameter.…”

“…These methodologies are based on the determination of the horizontal gradients of a measured parameter. The proposed solutions correlate ground faulting areas to high values of horizontal gradients of gravimetric anomalies [23], soil vibration frequency [32,33] and high values of horizontal gradients of subsidence magnitude [15,27]. Their results show that these methodologies can forecast shallow ground fault generation, but further research is still needed to determine critical gradient threshold values related to ground faulting developing in specific cases.…”

“…Studies dealing with monitoring and detecting subsidence are numerous [11][12][13][14][15][16][17], as well as works addressed to land subsidence modeling for calculating the expected magnitudes and rates of subsidence for different scenarios [18][19][20][21][22][23]. Nevertheless, subsidence risk assessment are still scarce [24][25][26][27][28][29].…”

“…For example some works propose methodologies for the determination of areas prone to develop subsidence-related faulting [23,26,27,[32][33][34]. Other works proposed methodologies to determine the areas that are likely to develop subsidence [29,35].…”

Risk Assessment of Land Subsidence in Kathmandu Valley, Nepal, Using Remote Sensing and GIS

“…The city has been suffering from groundwater extraction related subsidence since decades [21]. The city has been reported with subsidence reaching up to 38 cm/yr.…”