Observations from the Implementation of a Combined Active and Passive Surface Wave Based Methodology

摘要

This paper presents the application of a combined Multichannel Analysis of Surface Waves (MASW) and Microtremor Analysis Method (MAM) methodology using a linear array of 16 geophones in three selected sites. The methodology allows for a comparison of the dispersion curves generated independently from each technique and, if the dispersion curves yield consistent results, the development of a combined dispersion curve that has broader frequency content. In this study, the dispersion curves generated from MASW (active) and MAM (passive) surveys are compared and the reliability of the MAM results is associated to the relative orientation of the background noise and the linear array. It is observed that in the cases where the linear array is in-line with the propagation direction of the background noise, or when the background noise is omni-directional, the active and passive dispersion curves are consistent. When the linear array is oriented perpendicular to the background noise propagation direction, the passive data are unreliable and inconsistent with the active data, indicating higher apparent phase velocities. These observations are important, particularly, when implementing exclusively the passive technique as a site investigation tool.