THE ASSESSMENT INTERRELATIONSHIP BETWEEN FAR-FIELD AND NEAR-FIELD SEISMIC PARAMETERS USING THE CORRELATION CONCEPT

Ground motions consequent to an earthquake re ect the features of the seismic source, the rupture process, the source-site travel path, and local site conditions. Consequently, the characteristics of ground motion in the vicinity of an active fault can be signicantly dierent from those of the far-eld. Recordings from recent earthquakes show that near-eld earthquakes have dierent characteristics than far-eld earthquakes. Overall, these characteristics are caused by a directivity eect in near- eld earthquakes. This phenomenon causes the fault normal component of the recorded near-fault to have long-period velocity pulses. This paper investigates the relationship between the near-eld of seismic parameters, including range, energy and frequency content parameters, and the results are compared with far-eld earthquakes. 30 records of far and near-eld earthquakes have been used. The data were analyzed by the Pearson correlation coecient. It is a measure of the linear correlation (dependence) between two variables, X and Y, giving a value between +1 and -1 inclusive, where 1 is total positive correlation, 0 is no correlation, and -1 is total negative correlation. The results show that the correlation between the parameters of the horizontal component of near-eld not only has a direct relationship, but that the correlations, on average, are powerful. The results show that maximum velocity of ground motion is better than maximum acceleration in prediction of other seismic parameters in three-components. On the other hand, the relationships between horizontal and vertical components of the parameters of the near-eld dier considerably. So, in the horizontal component, no inverse relationship is seen between the parameters.