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Seismic site effects in the city of Mendoza and surroundings (Argentina)
Effets de site sismique dans la ville de Mendoza et les environs (Argentine)
Barchiesi A.M., Mancipe-Herrera C.
Geotechnical Research Section - IMERIS, Faculty of Engineering, National Cuyo University, Mendoza, Argentina.
ABSTRACT: The city of Mendoza and its surroundings constitute an urban nucleus developed in a region of strong seismic activity.
Therefore, studies aimed to establishing the local seismic response are needed. The first stage of these studies are given by the
compilation of geotechnical information enabling an approximate characterization of the existing alluvial deposits, in terms of their
shear wave velocities, soil densities and stiffness and damping degradation curves. On the other hand, assessments on the seismic site
effects were made taking into account the seismicity of the area by means of signals representing earthquakes both in near field
condition and in far and intermediate distant condition. Both activities have been carried out from the available information that is not
completely enough for a definitive study. This paper presents a synthesis of calculations of seismic site effects in different points of
the urban area are presented as information basis for the preparation of maps of free field maximum accelerations, surface
amplifications and design spectra.
RÉSUMÉ : La ville de Mendoza et ses alentours constituent un noyau urbain développé dans une région de forte activité sismique. Il
faut donc des études visant à établir la réponse sismique locale. La première étape de telles études est donnée par la compilation
d'informations géotechniques permettant une caractérisation approximative des dépôts alluvions existants, en fonction de leur vitesse
des ondes de cisaillement, la densité du sol et des courbes de dégradation de la rigidité et l'amortissement. En revanche, les
évaluations sur les effets de site sismique ont été faites au moyen de signaux des tremblements de terre les deux près de conditions sur
le terrain et en état proxène, lointain et intermédiaire, en tenant compte de l'activité sismique de la région. Les deux activités ont été
menées après les informations disponibles ne sont pas assez complètement pour une étude définitive. Ce document présente une
synthèse des calculs des effets de site sismique en différents points de l'agglomération comme base d'information pour la préparation
de cartes des accélérations maximales de champ libre, les amplifications de surfaces et les spectres del design.
KEYWORDS: Mendoza, seismic site effects, seismic micro-zonation, near field condition.
1
INTRODUCTION
Mendoza city and its surroundings, in the province of Mendoza,
is the fourth city by number of inhabitants of Argentina, with
about 850,000 inhabitants. Figures 1 and 2 illustrate the location
of the area and its six municipalities: Las Heras, Guaymallén,
Maipu, Godoy Cruz, Luján de Cuyo, and Capital (or Mendoza
city).
The area has been subjected to various seismic events during
its history, the most important of which was on the 20 March
1861 earthquake (estimated Richter magnitude: 7.2) with lX
Mercalli intensity. According to Mingorance 2006, the epicenter
of this event was located in the La Cal fault zone (though the
INPRES placed the epicenter in Barrancas, Maipú, Mendoza).
During the 20th century the area was affected directly by
events smaller than the aforementioned ones: 26 January 1985
(M: 5.7) with epicenter in Barrancas (25km to Mendoza city)
according to Poder Ejecutivo Nacional 1989.
This paper concerns a synthesis of the research developed to
determine approximately the surface seismic loads based on the
information available.
One aspect that has received particular attention is given by
the seismic site effects corresponding to the amplifications and
modifications that suffer the seismic loads when arriving to the
surface associated with the geotechnical characteristics of each
particular site. A general presentation of the problem can be
seen in Barchiesi et al 2010 and Barchiesi 2010. A more
detailed presentation can be found in Lanzo & Silvestri 1999.
A preliminary zoning based on the expected response, taking
into account the results of maximum acceleration, spectra of
pseudo-acceleration and periods of amplification was performed
in this study.
Figure 1: Location of Mendoza city and surroundings in Argentina
Also a study of sensitivity whereas the great uncertainty of
geotechnical parameters was taken into account was developed.
