Amplitude Inversion in Seismic Traveltime Tomography – An Application in Subsurface Imaging at a Historical Site

Seismic amplitude is an important parameter for it carries information about the structure of the subsurface which complements that provided by the traveltimes. However, both the need for a special pre-inversion processing of amplitudes and their complex relationship to subsurface features, has often resulted in a preference to traveltimes. Nevertheless, for relatively confined datasets and use of independent information, amplitudes can readily contribute to a better imaging and interpretation of subsurface features. The present work is concerned with the application of seismic first arrival amplitude inversion using ray theory, on a set of seismic tomographic data acquired at a historical site. Amplitude inversion results are compared with those of traveltime inversion. Results show that amplitudes and traveltimes are sensitive to different features of the subsurface. Attenuation distance is more related to the geological bedrock and deeper and broader (low wavenumber) structure, whereas velocity is more related to shallower and detailed (high wavenumber) structure. Amplitude inversion contributes thus to the improvement of the overall subsurface imaging. Seismic tomographic exploration of historical and other near surface sites of historical and engineering interest can benefit from the use of amplitude inversion.