ThesisPDF Available

Relaciones Neuronales Para Determinar la Atenuación del Valor de la Aceleración Máxima en Superficie de Sitios en Roca Para Zonas de Subducción

Authors:

Figures

Content may be subject to copyright.
A preview of the PDF is not available
Conference Paper
Full-text available
RESUMEN: En este artículo se presenta un modelo neuronal de atenuación sísmica capaz de estimar los valores de la aceleración máxima en superficie para sismos, registrados en sitios en roca, provenientes de zonas de subducción. El modelo está constituido por tres módulos neuronales de alimentación al frente y propagación rápida hacia atrás cuya construcción se realizó sobre 354 series de tiempo de aceleraciones en la estación Ciudad Universitaria CU (estación en superficie). La base de datos comprende sismos ocurridos desde la década de los 60 hasta el año 2013. ABSTRACT: In this paper, a neural seismic-attenuation model to estimate values of peak ground acceleration, registered in rock sites due to earthquakes originated on subduction zones, is presented. The model is constituted by three neural feed forward and quick back propagation modules which were developed using 354 acceleration time series recorded in Ciudad Universitaria CU station (surface station).The database includes earthquakes occurred from the early 60’s until 2013.
Article
Full-text available
Seismic gaps and recurrence periods of large, shallow interplate earthquakes along the Mexican subduction zone are reexamined after combining information from a catalog of nineteenth century's earthquakes, some relocated epicenters of the early part of this century, source parameters of recent large earthquakes, and redetermined magnitudes of great, shallow earthquakes of this century. Tehuantepec and Michoacan gaps have not experienced a large shock in this century and perhaps none in the past century; they are either aseismic or have anomalously large repeat times. Guerrero, Jalisco, and Ometepec regions presently appear to have a high seismic potential. Observed average repeat times of large earthquakes (Ms ≳ 7.4) in six regions (east, central, and west Oaxaca, San Marcos, Petatlan, and Colima) are between 32 to 56 yr. Data of this century indicate that the strain is released mostly in large events (Ms ≳ 7.4). A simple dislocation model with parameters obtained from the studies of recent earthquakes explains the observed recurrence periods quite well. The b value for this zone is not meaningful, an observation which is of significance for seismic risk estimation. Most of seismic moment (or, equivalently, seismic energy) release since 1800 appears to occur for 15 yr followed by relative quiescence in the next 15 yr.
Conference Paper
Full-text available
Cooperation between six Central American countries (Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama) and Norway, within the frame of the CEPREDENAC organization, has made it possible to collect, collate and analyze a data base of 280 sets of three-component strong motion recordings from Central America, including some recordings from the Guerrero array in Mexico in order to obtain a better coverage in magnitude and distance. Response spectral attenuation relations are developed.
Conference Paper
Full-text available
RESUMEN La aplicación de diferentes sistemas de aislamiento sísmico ha sido analizada en México durantes los últimos años por varios investigadores, aunque las aplicaciones prácticas han sido escasas, en parte por la falta de códigos de diseño específicos. Este artículo muestra el procedimiento desarrollado para obtener leyes de atenuación en aceleración (para el diseño de la estructura) y en desplazamiento (para el diseño propio de los mecanismos de aislamiento) a partir de acelerogramas registrados en la Costa Mexicana del Pacífico. Las leyes de atenuación obtenidas son el resultado del análisis de una base de datos de más de 2000 acelerogramas registrados de 1966 a 1999 en la zona de subducción entre Oaxaca y Michoacán. Las leyes de atenuación obtenidas son comparadas con aquéllas elaboradas hace más de diez años. ABSTRACT The application of different systems from seismic isolation has been studied in Mexico during the last years by some researchers, although there have been few applications of this technique, in part because of the absence of specific design guidelines advocated by building codes. This paper presents attenuation laws in acceleration (for the design of the structure) and in displacement (for the design of the isolation mechanisms) obtained from accelerograms registered in the Mexican Pacific Coast. The obtained attenuation laws are the result of the analyses of a database composed of more than 2000 acceleration records from earthquakes events recorded from 1966 to 1999 in the subduction zone between Oaxaca and Michoacán. The attenuation laws have been compared with those elaborated more than ten years ago.
Article
Attenuation relationships are presented for estimating peak acceleration and spectral velocities on rock sites in the near field of large subduction zone earthquakes. The attenuation relationships were developed from regression analysis of recorded ground motions and numerical simulations of ground motions for large earthquakes. The empirical data consists of the available recordings obtained on rock from 60 earthquakes including the 1985 events in Chile and Mexico. Near field, ground motions for events were simulated by superposition of a large number of subevents. The source models for the subevents were derived from finite difference simulations of faulting and wave propagation was modeled using ray theory.
Article
This paper presents the application of artificial neural networks (ANNs) for the estimation of peak ground acceleration (PGA) for the earthquakes of magnitudes more than 5.0 and hypocentral distances less than 50 km. Earthquake magnitude, hypocentral distance, and average values of four geophysical properties of the site, i.e., standard penetration test (SPT) blow count, primary wave velocity, shear wave velocity, and density of soil, have been used as six input variables to train the neural network. An attempt has also been made to train the neural network with magnitude, hypocentral distance and average shear wave velocity as three input variables. This study shows that ANN is a valuable tool for the prediction of peak ground acceleration at a site, given the magnitude and location of earthquake, and local soil conditions. It has also been observed that the prediction using the trained network with six inputs is better than that with three inputs.
Article
We have taken advantage of the recent increase in strong-motion data at close distances to derive new attenuation relations for peak horizontal acceleration and velocity. This new analysis uses a magnitude-independent shape, based on geometrical spreading and anelastic attenuation, for the attenuation curve. An innovation in technique is introduced that decouples the determination of the distance dependence of the data from the magnitude dependence. The resulting equations are log A = − 1.02 + 0.249 M − log r − 0.00255 r + 0.26 P r = ( d 2 + 7.3 2 ) 1 / 2 5.0 ≦ M ≦ 7.7 log V = − 0.67 + 0.489 M − log r − 0.00256 r + 0.17 S + 0.22 P r = ( d 2 + 4.0 2 ) 1 / 2 5.3 ≦ M ≦ 7.4 where A is peak horizontal acceleration in g, V is peak horizontal velocity in cm/ sec, M is moment magnitude, d is the closest distance to the surface projection of the fault rupture in km, S takes on the value of zero at rock sites and one at soil sites, and P is zero for 50 percentile values and one for 84 percentile values. We considered a magnitude-dependent shape, but we find no basis for it in the data; we have adopted the magnitude-independent shape because it requires fewer parameters.
Article
We present attenuation relationships for peak ground acceleration and response spectral acceleration for subduction zone interface and intraslab earthquakes of moment magnitude M 5 and greater and for distances of 10 to 500 km. The relationships were developed by regression analysis using a random effects regression model that addresses criticism of earlier regression analyses of subduction zone earthquake motions. We find that the rate of attenuation of peak motions from subduction zone earthquakes is lower than that for shallow crustal earthquakes in active tectonic areas. This difference is significant primarily for very large earthquakes. The peak motions increase with earthquake depth and intraslab earthquakes produce peak motions that are about 50 percent larger than interface earthquakes.