Seismic wave attenuation characteristics of tertiary sediments in niger delta field | Abstract
Scholars Research Library

Scholars Research Library

A-Z Journals

+44 7389645282

Archives of Applied Science Research


Seismic wave attenuation characteristics of tertiary sediments in niger delta field

Author(s): Dagogo T, Ehirim CN, Ebeniro JO

Seismic attenuation analysis is important for several reasons, including aiding seismic risk evaluation. Quality factors and attenuation coefficients have been estimated for an X-field in the Niger Delta, whose near surface sediments has remained largely uncharacterized. Using surface waves extracted from seismic data acquired by conventional reflection methodology and employing the quality factor versus offset (QVO) technique of attenuation analysis, reliable attenuation coefficient and quality factor distributions for the field covering about 25 km2 has been generated. The value of quality factors obtained indicate that the near surface sediments are low in attenuation to surface waves, being largely unconsolidated. The value of quality factors ranges from 20 to 80, corresponding to attenuation coefficients of between 0.0006 to 0.002 m-1. The estimated attenuation factors in this study tend to have some form of dependence on the thickness of unconsolidated sediments. In most parts of the field, especially in the northern parts it is observed that areas with thin unconsolidated sediments thickness have higher attenuation factors than areas with thick unconsolidated sediments. These results correlates well with those of previous studies in similar geologic settings. Generally, the field is low in attenuation with high quality factors and therefore, susceptible to seismic hazards due to surface wave amplifications. This however, will enhance stress levels and distribution in the near surface sediments which will affect the stability of civil structures. Therefore, appropriate engineering standards must be adopted to ensure stability of engineering structures in the field.