The Mexico Earthquake of September 19, 1985—New Accelerograph Network for Mexico City

1989 ◽  
Vol 5 (1) ◽  
pp. 249-255 ◽  
Author(s):  
J. M. Espinosa-Aranda ◽  
A. Uribe ◽  
B. Frontana ◽  
O. Contreras ◽  
G. Ibarrola

As a result of the observed effects induced by the earthquakes of September 1985 in Mexico City's structures, the local government authorities increased their support for the installation of accelerographs in a network covering different zones of Mexico City. This paper presents the activities developed by the Centro de Instrumentación y Registro Sísmico (CIRES) concerned with: selection and procurement of suitable instruments, identification of the installation sites, and the installation of field stations. We also describe methods applied to the processing of seismic records and include a summarized catalog of accelerograms recorded to date.

2018 ◽  
Author(s):  
Itzel Coca Rios

Between 2012 and 2014, there were ten events in Mexico City that were repressed through arbitrary arrests which affected 365 persons. Through data analysis about the protest in that period it’s verified a change in police strategy by means of more selective tactics of repression and protest disarticulation. A sample of massive demonstrations with more than 2 thousand assistants was taken to test the hypothesis of repression as a response to two main characteristics of the events: 1) a protest directed to the federal scope, that local government cannot negotiate with, and 2) that threatens public order and status quo through: violence, several claims directed to many authorities, and radical petitions. The binomial logistic regression with “rare events” package and QCA tests reveal that the federal scope of the claim and the presence of violence from the protestors are necessary conditions for the repression to occur, while radicalism and variety of claims receive partial support. The study concludes with a nested analysis of the cases of December 1st 2012 and 2013.


1989 ◽  
Vol 5 (1) ◽  
pp. 41-50 ◽  
Author(s):  
E. Sordo ◽  
A. Terán ◽  
J. J. Guerrero ◽  
H. Juárez ◽  
J. Iglesias

This paper describes the study of a twelve floor concrete building with a waffle slab system located 300 meters from the accelerometer at Secretaria de Comunicaciones y Transportes (S.C.T) in Mexico City. First, the reduced seismic coefficient associated with the failure of the critical story is calculated by a linear dynamic analysis which reproduces the damage provoked by the 1985 earthquake to the real structure. Second, the ductility factor associated with the damaged stories is obtained through a step-by-step non-linear dynamic analysis. Finally, the peak value of the S.C.T. maximum ordinate for spectral response corresponding to 5 percent of critical damping was determined from this analysis.


1989 ◽  
Vol 5 (1) ◽  
pp. 153-174 ◽  
Author(s):  
D. A. Foutch ◽  
K. D. Hjelmstad ◽  
E. Del Valle Calderón ◽  
E. Figueroa Gutiérrez ◽  
R. E. Downs

The earthquake that shook Mexico City on 19 September 1985, destroyed several hundred buildings and took thousands of lives. Two buildings located in the most highly damaged part of the city experienced strong shaking, but suffered only slight damage. These reinforced concrete frame buildings had been retrofit with steel bracing systems and infill reinforced concrete walls prior to the earthquake. Forced vibration tests, analytical studies and geotechnical investigations for each building have been conducted. The results indicate that the steel bracing systems strengthened the buildings and stiffened them, moving their natural periods away from the 2.0-second predominant ground period in that part of the city. Implications for the design of strengthening systems have been determined.


1989 ◽  
Vol 5 (1) ◽  
pp. 145-151 ◽  
Author(s):  
J. Aguilar ◽  
H. Juárez ◽  
R. Ortega ◽  
J. Iglesias

The 1985 Mexico City earthquake caused very serious damage, especially in reinforced concrete buildings, making it necessary to repair and strengthen many structures. The authors had the opportunity to study 114 of these retrofitted buildings. The data base created with the collected information contains the description of the building, its damages and the retrofitting techniques used. The statistical analysis of this information makes it possible to identify the correlation among the structural and foundation types, the dominant failure modes, the causes of damage and the repair and strengthening techniques used in this group of buildings.


1989 ◽  
Vol 5 (1) ◽  
pp. 175-193 ◽  
Author(s):  
M. Jara ◽  
C. Hernández ◽  
R. García ◽  
F. Robles

It is the aim of this paper to describe the most important techniques that are being used in Mexico City to retrofit buildings damaged during the 1985 earthquake. The information is presented by means of four case studies. These cases offer practical design examples of the typical solutions adopted and illustrate the various aspects of the repair and strengthening process such as damage assessment, emergency measures for temporary protection, the retrofitting technique employed in each case and considerations and decisions made in the analysis and design.


1988 ◽  
Vol 4 (3) ◽  
pp. 469-479 ◽  
Author(s):  
S. Tobriner

Why is one of the most populous cities in the world built on land which has a history of subsidence, seismicity, and flooding? Mexico City illustrates how early decisions in a city's history can create difficult conditions for building well and living safely. The Aztecs had little choice but to live on the muddy islands in Lake Texcoco which now lie beneath downtown Mexico City. But the Spanish did have a choice. By selecting the island capital of Tenochtitlan for their colonial capital they bequeathed to succeeding generations problems which were apparent to them almost immediately after they began construction. Their solution to the hydraulic problems of the site only exacerbated ecological and seismic problems which the inhabitants of Mexico City face today, and destroyed the reason the first settlers inhabited the Valley of Mexico.


1989 ◽  
Vol 5 (1) ◽  
pp. 121-143 ◽  
Author(s):  
E. Miranda ◽  
V. V. Bertero

This paper summarizes the results of analytical studies conducted to understand the observed performance of low-rise buildings located in the soft-soil zone of Mexico City during the 1985 Michoacan earthquake. Two low-rise reinforced concrete moment resistant space frames were designed in accordance with the 1976 Code for the Federal District of Mexico. They were subjected to a series of static and time history dynamic analyses. The results indicate that the designed buildings have significantly larger lateral strengths than required by the Code and that these overstrengths were the main reason for the excellent performance of most of the low-rise buildings in Mexico City during the 1985 Michoacan earthquake.


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