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Copyright of Revista EIA is the property of Escuela de Ingenieria de Antioquia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Boletín de Ciencias de la Tierra is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A problem in the reflection seismology is the precise determination of field statics correction that have to be applied to the reflection data in order to eliminate effects of weathering layer. Normally these corrections are calculated by shallow Reflection Surveys. The waves refractated at the weathering layers are in the reflection seismograms and constitute part of the called "first breaks". These are waves where the source-receiver ray trajectories are located within the weathering layer and partly along its bottom. The arrival times through the weathering layer needed to computed the field statics corrections. In this work, a simple and efficient method is described to obtain field statics using only field seismograms recorded by the CDP configuration. As input data ones considered: a) the surface topography of the seismic line, b) the first breaks and c) the geometry data. The method consists of determining from a starting velocity model, this model has a layer constructed taking into average thickness a velocity for the area. The method propose to seismic processing, was tested on raw register an a seismic line with abrupt topography in a Colombia area. The obtained corrections with variable velocity were better than those computed with a constant velocity model. The statics solutions are necessary to obtain a good subsurface image. But in the initial processing sequence it is necessary, and do not spend time in surveys with other process, that do not resolve the static problem. In this paper a processing using static model calculate with variable velocity is proposed. This method have been development in the processing data in areas with irregular surface. For instance, Piedemonte Llanero. The software calculation is ProMAX, algorithm Gauss-Sediel. [ABSTRACT FROM AUTHOR]

In order to establish the regional model of attenuation of macroseismic intensity with distance in the Colombian territory, the isoseismal maps of thirty four strong earthquakes were analysed in this paper. Using some teorical models of attenuation and the macroseismic focal depth we chose three different intervals (h ≤ 20km, h ≤ 60 km and h > 60 km). From here the following three attenuation relations were obtained: Ii=I0 -0.019(x-15)-0.76 ln(x-15), con σ² =0.08; para h≤20km I =(2.3mb - 6.8)1.lx-0.06 e-0.001x, con σ² =0.26; para h≤60km I = I01.26e-0.004x, con r² =0.80; para h>60km For superficial earthquakes, the geometrical spreading coefficient its more important than the coefficient of physical absorption. [ABSTRACT FROM AUTHOR]