RE.MI. technique (REfraction MIcrotremors) belongs to passive seismic surveys methodologies. Created by the University of Reno in Nevada (USA), it is similar to the MASW, as far as, the operating simplicity and the idea of using the analysis of surfeys waves to go back to the stratigraphic model, is concerned; but it is different because it uses the recording of vibrations coming from sources which are distant from the site to be investigated.
The distance of the sources allows to analize more in detail the low-frequency components of the surface waves and then to reach greater depths of investigation. Furthermore this methodology is more appropriate (compared to the MASW) to the use within the urban sector, where the seismic noise is inevitable and represents a disadvantage for the active technicques, while it is advantageous for the RE.MI.
A limitation of this technique is the necessity of a omnidirectional origin of the microtremors. The instrument needed is basically the same used for refraction seismic and active MASW, eventually with lower frequency