Evaluación del hipotético sistema de falla transcurrente este-oeste de Costa Rica
Fecha
1996
Tipo
artículo original
Autores
Fernández Arce, Mario Enrique
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Resumen
Se analizaron los siguientess criterios que ayudan a evaluar la existencia de un sistema de fallas mayor en la parte central de Costa Rica: configuración geologica del territorio costarricense, fallamiento, distribución de la simicidad total del area, dstribución de sismos mayores, mecanismos focales, la transcurrencia profunda y resultados de datos gravimétricoe. El fallamiento predominante es el de orientación noroeste seguido por el noreste. Fallas de orientación este-oeste, requisito importante para la existencia de un sistema transcurrente en la parte central de Costa Rica son muy escasas.
La distribución de sismos indica que en las dos cordilleras hay fuentes sísmicas. En in Cordillera volcánica central ral (CVC) los temblores ocurren principalmente en las depresiones ubicadas entre los macizos volcánicos. La Cordillera de Talamanca tiene mayor sismicidad que CVC y hay por lo menos cinco importantes focos sísmicos en ella. Temblores de magnitudes superiores a 5 se han registrado en ambas cordilleras. Los mecanismos focales son principalmente normales. Los transcurrentes no sugieren un fallamiento de orientacion este-oeste, ni noreste, más bien indican activación de fallas con rumbo noroeste.
Se compararon lineamientos obtenidos con datos gravimétricos con el hipotético trazo de la falla transcurrente de Costa Rica pero no se encontró correlación entre ellos. Se concluye que no hay evidencia del sistema de falla transcurrente en la parte central de Costa Rica.
The following criteria were analysed in order to evaluate the existance of the hipotetic transcurrent fault system (FTCR) of Costa Rica in its central part: geologic setting, faulting, earthquakes distribution, focal mechanisms, deep transcurrence, and gravimetric data. The predominant faulting is the one with northwest orientation, secondly the faulting with the northeast orientation. This faulting is more abundant in the Talamanca Ridge rather than the Central Volcanic Ridge. Faults oriented east-west, a neccesary requirement of the existence of FTCR, are scarce. The distribution of epicenters indicates that in both ridges there are seismic resources. In the Central Volcanic Ridge earthquakes take place in spaces between volcanoes. In the Talamanca Ridge there are at least five very active seismic zones. Earthquakes with more than 5-degrees in magnitud occur in both ridges. Focal mechanisms are manily normal. Transcurrent mechanisms suggest an active faulting oriented Northwest. There is no correlation between gravimetric lineament and the FTCR. To conclude, there is no geophysical evidence of the FTCR in the central part of Costa Rica.
The following criteria were analysed in order to evaluate the existance of the hipotetic transcurrent fault system (FTCR) of Costa Rica in its central part: geologic setting, faulting, earthquakes distribution, focal mechanisms, deep transcurrence, and gravimetric data. The predominant faulting is the one with northwest orientation, secondly the faulting with the northeast orientation. This faulting is more abundant in the Talamanca Ridge rather than the Central Volcanic Ridge. Faults oriented east-west, a neccesary requirement of the existence of FTCR, are scarce. The distribution of epicenters indicates that in both ridges there are seismic resources. In the Central Volcanic Ridge earthquakes take place in spaces between volcanoes. In the Talamanca Ridge there are at least five very active seismic zones. Earthquakes with more than 5-degrees in magnitud occur in both ridges. Focal mechanisms are manily normal. Transcurrent mechanisms suggest an active faulting oriented Northwest. There is no correlation between gravimetric lineament and the FTCR. To conclude, there is no geophysical evidence of the FTCR in the central part of Costa Rica.
Descripción
Palabras clave
Sistema de fallas mayor, COSTA RICA, Fallamiento, SISMO, Mecanismos focales