Geophysical evi-dence of the 1912 earthquake rupture along the central fault system of the Acambay Gra-ben, Central Mexico

Evidencias geofísicas de la ruptura del sismo de 1912 a lo largo del sistema de fallas central del Graben de Acambay, Centro de México

Pierre Lacan^1,*, Clau-dia Arango-Galván²

¹ Centro de Geociencias, Universidad Nacional Autónoma de México, Blvd. Juriquilla, 3001, 76230, Juriquilla, Querétaro, México.

² Instituto de Geofísica, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica S/N, Ciudad Universitaria, 04510, Ciudad de México, México.

* Corresponding author: (P. Lacan) This email address is being protected from spambots. You need JavaScript enabled to view it.

How to cite this article:

Lacan, P., Arango-Galván, C., 2021, Geophysical evidence of the 1912 earthquake rup-ture along the central fault system of the Acambay Graben, Central Mexico: Boletín de la Sociedad Geológica Mexicana, 73 (2), A250121. http://dx.doi.org/10.18268/BSGM2021v73n2a250121

ABSTRACT

In this work, we have applied two geophysical techniques in two different areas of potential interest for paleoseismological assessment of the active faults of the Acambay graben. The main goal was to localize segments of buried faults suspected to break the surface during the 1912 Acambay Earthquake, in order to (1) identify favorable sites for paleoseismological investigation purpose and (2) extrapolate the data obtained with a paleoseismic trenching. On the one hand, Electromagnetic Induction (EMI) Method was used to map the horizontal variation of the apparent resistivity in order to detect the 1912 surface rupture of the Temascalcingo fault in the alluvial plain of the Lerma River. On the other hand, within a volcanic edifice, the Electrical Resistivity Tomography (ERT) tech-nique was used to characterize the electrical resistivity distribution along a profile in or-der to detect and localize the San Pedro fault, partially buried in a Holocene sedimentary filling of a small endorheic basin. Results of these studies allow defining location and orientation of the structures that potentially broke the surface during the 1912 earthquake and are partially hidden by recent deposits filling the tectonic depressions. Good correla-tion between ERT subsurface to deep imagery of faults and a trench survey which cuts across the San Pedro fault trace, illustrate the pertinence to use such techniques for pale-oseismological investigation purpose in volcano-sedimentary environments.

Keywords: active fault, geophysical characterization, electrical resistivity tomography, electromagnetic induction, paleoseismology, Temascalcingo fault, San Pedro fault.