Shallow structure of the Chalco and Xochimilco sub-basins (southern Mexico basin) based on wave propagation modelling and seismic data

Researchers have mapped the shallow geological structures of the Chalco and Xochimilco sub-basins, part of Mexico City's UNESCO-listed historic center, revealing a complex volcanic-sedimentary infill shaped by tectonic forces. Using seismic data from a 3000 m deep well and wave propagation modeling, they identified key features such as the base of lacustrine sediments and basaltic basement, separated by structural highs interpreted as volcanic flows. The study found that the Xochimilco sub-basin's shallow lacustrine sediments thin northwestward, while Chalco's reflectors indicate deformation during deposition. High-amplitude seismic reflections suggest impedance contrasts between geological units, with strata thicknesses implying sedimentation cycles of ~30,000 years. This work provides a foundation for understanding seismic amplification in these tectonic depressions and reconstructs paleo-environmental changes in the southern Mexico Basin over the last 250,000–375,000 years.

González-Flores, E., Campos-Enríquez, J. O., Wong, R. V., Torres-Verdín, C., Rivera-Recillas, D. E., & Camacho-Ramírez, E. (2020). Shallow structure of the Chalco and Xochimilco sub-basins (southern Mexico basin) based on wave propagation modelling and seismic data. Journal of South American Earth Sciences, 103, 102722. https://doi.org/10.1016/j.jsames.2020.102722