Subsoil Characteristics of Mexico City, acceleration and hysteretic energy spectra for the Mexico Earthquake of September 19, 2017

The September 19, 2017 intraslab earthquake (Mw7.1), whose epicenter was located near the limits between the states of Puebla and Morelos at approximately 120km from Mexico City, caused severe damage in these regions. In Mexico City more than 40 buildings collapsed, and hundreds had moderate to severe damage; dozens of them are to be demolished. This article analyzes the spectral ratios of accelerometric stations in the lake-bed of Mexico City with respect to the average Fourier spectra at hill zone sites in order to study and compare over time the changes in the behavior of local effects and their relationship with the damage presented during this earthquake; these ratios exhibit also the settlement problem in some places in the city due to over exploiting the aquifer for water supply purposes. Finally, pseudoacceleration and hysteretic energy maps for Mexico City with a discussion with a possible correlation with reported damages are presented.