Identification and assessment of land subsidence development in rural areas using PS interferometry: a case study in Western Michoacan, Mexico

Characterization of land subsidence in Mexico has been primarily done in major cities, leaving aside smaller populations. Consequently, there are no data regarding the number of towns affected by this phenomenon, including its spatial extension or deformation rates that could prevent severe damages, such as those recorded in the most studied cases throughout the country. One of these overlooked regions is the western part of Michoacan state, where Zamora is the only city known to have subsidence rates of 13 cm/year. This region is characterized by volcanic ranges and tectonic valleys filled by fertile unconsolidated fluvio-lacustrine sediments, which allow agriculture activity based on groundwater extraction through a high density of wells (up to 22 wells/km 2 ) in overexploited aquifers. Therefore, this paper focuses on identifying localities affected by subsidence and assessing the relationship between the well density and the spatio-temporal evolution of the phenomenon. For this purpose, persistent scatterer (PS) interferometry was applied, covering six years and four months (from October 2014 to February 2021). The results allowed to identify 20 localities impacted by subsidence, 19 that had not yet been reported. In the west, the affected populations, around Yurecuaro, Sahuayo, and Zamora valleys, have well-developed subsidence patterns and rates above 20 mm/year. In the east, villages have a less developed subsidence pattern and rates below 20 mm/year. The subsidence type impacting the villages in Tarimbaro-Cuitzeo grabens, Sahuayo, and Zamora valleys show evidence of a structural configuration that controls the phenomenon, while regional subsidence affects the rest of the localities.