Empirical Ground-Motion Relations in Northeastern Mexico from intraplate moderate earthquakes
Por:
Villalobos-Escobar, Gina P., Marquez-Ramirez, Victor H., Castro, Raul R., Pena-Alonso, Tomas A.
Publicada:
17 feb 2023
Ahead of Print:
1 feb 2022
Resumen:
We present attenuation relations for peak ground velocity (PGV) and
acceleration (PGA) for northeastern Mexico, where seismic activity has
been underestimated over the years. We tested four models derived from a
parametrical form previously proposed for intraplate earthquakes in
Central Mexico but using regional data recorded by the Mexican National
Seismological Service (Servicio Sismologico Nacional de Mexico, SSN).
For comparison and as a selection criteria, we used the decaying trend
of the models, the ratio between the observed and the predicted data
(logarithmic) as a function of the distance and its standard deviation,
and we determined the following attenuation relations:
log PGV = -4.36 + 0.8Mw - 0.00015R - 0:97 log(R) - 0.0041H + sigma(A) +
sigma(E)
log PGA = 0.31 + 0.23Mw + 0.0011R 1:48log(R) 0:0022 + sigma(A)
Where M-W is the moment magnitude, R the hypocentral distance, and H the
focal depth (both in km). sigma(A) and sigma(E) correspond to the
intra-event and inter-event standard deviations. For PGV sigma(A) and
sigma(E) are 0.18 and 0.004, while for PGA sigma(A) and sigma(E) are
0.25 and 0.30, respectively. We found that by using the original
distance definition R, (dependent on the hypocentral distance and on the
magnitude altogether), the results are basically the same as when using
the hypocentral distance directly. We also tried to incorporate an
independent variable to characterize the local soil conditions of the
recording stations. Despite the fact of finding a good residual behavior
with that incorporation, the empirical functions of acceleration (PGA)
stopped decaying around 250 km, implying a physical impasse and making
the models inadequate for greater distances, situation that did not
occur with velocities (PGV). The obtained constants found for the local
site conditions on both PGA and PGV were similar between stations,
showing no strong impact on the site effects on the predictive
equations. The proposed models fulfill the purposes of having small
residual fitting and simple attenuation relations that depend only on
magnitude, hypocentral distance and focal depth, making them practical
and easy to apply for engineering or seismic risk assessment purposes
with the available data from local or regional networks.
Filiaciones:
Villalobos-Escobar, Gina P.:
Univ Autonoma Tamaulipas UAT, Fac Ingn Arturo Narro Siller, Tampico, Mexico
Marquez-Ramirez, Victor H.:
Univ Nacl Autonoma Mexico, Ctr Geociencias CGEO, Juriquilla, Mexico
Castro, Raul R.:
Ctr Invest Cient & Educ Super Ensenada CICESE, Dept Sismol, Div Ciencias Tierra, Ensenada, Baja California, Mexico
Pena-Alonso, Tomas A.:
Univ Autonoma Tamaulipas UAT, Fac Ingn Arturo Narro Siller, Tampico, Mexico
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