Detecting Underground Mines by Seismic Noise Autocorrelation and
Geophysical Methods
- Martín Cárdenas-Soto,
- Jesús Sánchez-Gónzalez,
- José Martínez-González,
- Gerardo CIFUENTES-NAVA,
- David Zenil
Martín Cárdenas-Soto
National Autonomous University of Mexico (UNAM), National Autonomous University of Mexico (UNAM)
Corresponding Author:martinc@unam.mx
Author ProfileJesús Sánchez-Gónzalez
National Autonomous University of Mexico (UNAM), National Autonomous University of Mexico (UNAM)
Author ProfileJosé Martínez-González
National Autonomous University of Mexico (UNAM), National Autonomous University of Mexico (UNAM)
Author ProfileGerardo CIFUENTES-NAVA
UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO, UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO
Author ProfileDavid Zenil
National Autonomous University of Mexico (UNAM), National Autonomous University of Mexico (UNAM)
Author ProfileAbstract
Seismic noise correlation is one of the most used tools to know the
earth's structure in the last decade. In this study, we used
autocorrelation to determine the presence of underground mines by
extracting the normal seismic response in transmission between the
ground surface and the cavity roof. The experiments are carried out in
the urban environment of the Mexico City western zone, where a high risk
of mines collapse subsists. For this, we use ambient noise recorded for
30 min in vertical 4.5 Hz geophone arrays. We obtain zero offset
sections of power spectra density from the stacking of autocorrelations
in 4 s time windows. The results are compared with GPR, ERT, and seismic
refraction studies. We observe that surface cavities such as drainpipe
systems are present at frequencies greater than 30 Hz. Between 10 and 30
Hz, the seismic response is produced by resonances associated with
cavities that can be delimited laterally by spectral maxima and whose
presence agrees with discontinuities on radargrams. The mine roof depth
is related to half-wavelength and the compression wave velocity of the
surface layer determined by seismic refraction. The autocorrelation
method does not determine the shape or vertical extent of the cavity,
which is well resolved by the high resistivity values of the ERT method.
However, low spectral amplitudes are observed on saturated materials
where the electromagnetic wave is noisy and low resistivity values are
resolved.