GEOPHYSICAL SUBSOIL CHARACTERIZATION OF A HOUSING UNIT SHAKEN BY THE
EARTHQUAKE OF SEPTEMBER 19, 2017 (MW 7.1)
Abstract
September 19, 2017 earthquake considerably affected the southern area of
Mexico City; specically, in the transition zone, some local subsidence
problems were accentuated. This site is associated with a high
geological hazard due to faults, cracks, subsidence, landslides, and
collapses. The lesson learned from this earthquake showed that much
remains to be known, and detailed characterization is needed to dene
vulnerable sites that allow for reduction seismic-geological risk. This
study used various geophysical methods to explore the subsoil of a
housing unit south of Mexico City. The houses began having structural
damage on the site, and the surface of the land presented cracks since
the year 2012, problems that were magnied after the earthquake. We apply
electrical tomography, seismic noise interferometry, and H/V methods.
The results show the properties of the subsoil vary drastically both in
the lateral direction and in-depth. In particular, it highlights the
presence of a discontinuity that divides the area into two different
structures. Our interpretations show that the observed damages are due
to a series of conjugated events that accentuate differential
subsidence: irregularity in subsoil structure and properties, local
overexploitation of groundwater, and dynamic amplication effects that
accelerate relative displacements during seismic motions.