Seismological Research Letters; November/December 2007; v. 78; no. 6;
p. 635-648; DOI: 10.1785/gssrl.78.6.635
© 2007 Seismological Society of America
A Report on the Atoyac, Mexico, Earthquake of 13 April 2007 (Mw 5.9)
S. K. Singh1,2,
M. Ordaz2,
J. F. Pacheco1,
L. Alcántara2,
A. Iglesias1,
S. Alcocer2,
D. García1,
X. Pérez-Campos1,
C. Valdes1, and
D. Almora2
L. A. Aguilar2,
M. Ambriz2,
J. G. Anderson3,
M. Ayala2,
C. Cárdenas1,
G. Castro2,
J. L. Cruz1,
R. Delgado2,
L. Domínguez4,
J. Estrada1,
S. I. Franco1,
L. E. Flores4,
C. Gutierrez4,
M. A. Macías2,
I. Molina2,
C. Morquecho4,
J. Ortíz1,
M. A. Pacheco-Martínez4,
A. Quezada1,
R. Quaas4,
L. Quintanar1,
C. Pérez2,
J. Perez1,
A. L. Ruiz2,
H. Sandoval2,
M. Torres2,
R. Vázquez2,
J. M. Velasco2,
J. Velázquez2, and
M. Velázquez2
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INTRODUCTION
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An inslab earthquake occurred below Atoyac, Guerrero, Mexico, on 13 April
2007 (Mw 5.9) at a depth of 37 km. It was strongly felt in
Acapulco (
65 km) and Mexico City ( 270 km); the peak
ground accelerations (PGAs) at soft sites in these two cities were as high as
200 cm/s2 and 12 cm/s2, respectively. This was the first
significant earthquake in Mexico since the recent strengthening of
strong-motion and broadband networks in the country. This was also the first
moderate event for which ground-motion maps for Mexico City were produced and
distributed without human intervention in near real time. In this paper, we
report on the source characteristics and the tectonic implications of the
earthquake and the ground motions that it produced. We also discuss the
performance of the seismic alert system (SAS) and near real-time generation
and distribution of expected ground-motion maps for Mexico City during the
earthquake.
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DATA AND ANALYSIS
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Our analysis of the Atoyac earthquake is based on broadband seismograms and
accelerograms from stations operated by the National Seismological Service
(SSN) of the Instituto de Geofísica (IG) at the Universidad Nacional
Autónoma de México (UNAM), and the Instituto de
Ingeniería (II), UNAM. We also used data from an accelerograph operated
by the Centro Nacional de Prevención de Desastres (CENAPRED) in
Acapulco.
About 35 aftershocks with M 
3.4 were reported by SSN in the
first four days of the earthquake, the largest being one of magnitude 5.3. The
SSN network is sparse. However, the accelerograph network operated by the II
is relatively dense in Guerrero (Anderson
et al. 1994) where a mature seismic gap has been
identified (Singh et al.
1981). Merged data from both networks permit reliable location of
earthquakes in the region. As the accelerograms from the II network are . . . [Full Text of this Article]
Instituto de Geofísica
Universidad Nacional Autónoma
de México
C.U. 04510. México
D.F.
krishna@ollin.igeofcu.unam.mx
(S.
K. S.)
Copyright © 2009 by Seismological Society of America
