Seismic noise array measurements using broadband stations and vertical geophones: preliminary outcomes for the suitability on f-k analysis

In recent years, seismic noise array measurements have emerged as a promising way for estimating Vs profiles and characterizing the corresponding soil structure. Although methods based on analysis of seismic noise are simpler, cheaper and faster than conventional soil penetrating techniques, array deployment requires the use of several stations which are not always available for all the research groups. Broadband stations are expensive, but even short-period sensors can require a significant economical effort as it is necessary to use several. In this paper, the results from broadband stations and vertical geophones using the f-k method have been compared. Circular arrays with both types of instruments were installed north and south of the Himalayan Frontal Thrust (HFT) also known as Mohand Thrust, with different soil characteristics. The comparison carried out in terms of dispersion curves shows an excellent agreement between broadband stations and geophones recordings in the frequency range of applicability of the arrays used. These results indicate the possibility of using seismic refraction equipments for the f-k analysis in the frequency band of geotechnical engineering interest. This has potentially great importance since the same equipment is indicated to be applicable for both seismic noise measurements as well as for active reflection seismic surveys.