Exploring a near‐surface subsidence over a rehabilitated underground mine through ambient seismic noise tomography in combination with other geophysical methods

Abstract

An unexpected surface subsidence in Mexico City on 19 May 2015 prompted a detailed geophysical investigation of the three‐dimensional structure of a collapsed‐soil mine located in a section of the Chapultepec Park in the vicinity of an artificial lake. As revealed from past geological explorations, the subsoil at the site consists of volcano‐sedimentary materials that were quarried in the mid‐20th century; subsequently, during the construction of the park, most of those mines had been only partially rehabilitated, with a potential risk of land subsidence. Near‐surface imaging techniques based on ambient seismic noise as well as microgravimetry, electrical resistivity tomography, shallow seismic refraction methods were evaluated for their applicability to characterize the structure of the collapsed mine. Tomography images computed using ambient‐noise array data characterized the extent of the underground mine showing high‐velocity anomaly, while results from microgravimetry and electrical resistivity tomography analyses indicated the structure through weak contrasts in gravity and resistivity anomalies. Additionally, electrical resistivity tomography results also illustrated the saturated nature of the subsoil. While different methods exhibit different capabilities to constrain such a small spatial feature, the present study highlighted the scope of an integrated approach in confirming the existence of potential voids as well as to estimate soil‐subsidence hazard. In terms of operational convenience and rapid performance, the ambient noise tomography method proved to be a relatively efficient and economical reconnaissance tool for identifying 3D velocity contrasts in an urban environment.

Application of microgravity and electrical resistivity imaging techniques to identify ground subsidence prone zone

“…In general, it is useful as a complementary tool in the structural interpretation of the subsurface geomaterials, as it allows the identification of anomalies with low and high amplitude. As reported by Cárdenas-Soto et al (2020), the TDR filter tends to constraint the amplitude of potential field to values ranging from − /2 to + /2.…”

“…soil compaction, development of subterranean voids by the solution of host rocks, tectonic and volcanic activities) and anthropogenic activities (e.g. subsurface mining, tunnel construction and extraction of groundwater) are known to be the principal causes of subsidence (Cárdenas-Soto et al, 2020;Marschalko et al, 2015). The aftermath of ground subsidence is often disastrous, especially in the urban area.…”

“…Near-surface geophysical techniques such as Microgravity Imaging, Electrical Resistivity Imaging, Ground Penetrating Radar, Seismic Refraction and Ambient Noise Tomography offer a solution to the aforementioned limitation of RS and GIS techniques (Cárdenas-Soto et al, 2020;Martínez-Moreno et al 2013;Sastry and Mondal, 2013). Quite a number of researchers employed the geophysical techniques to study subsidence.…”