GNGTS 2018 - 37° Convegno Nazionale

662 GNGTS 2018 S essione 3.2 In order to determine the position of each measuring point and so create a geo-referenced grid (Fig. 1d), a GNSS survey (Global Navigation Satellite System) was carried out using a Topcon HiperSR (a dual frequency receiver, 256 channels). The GNSS receiver has been configured in Stop and Go mode. Normally this method is based to use a reference point (of known coordinates). For this survey the permanent station RESU (Resuttano), belonging to RING network (INGV RING Working Group, 2016) was chosen as reference site, and a second receiver (rover), is used to acquired points, moving at regular intervals on the studied area. The Stop and Go method require the continuous recording of at least four satellites. During the recording, 18 satellites were visible. The data acquired has been post-processed with Magnet Office Tool software. Fig. 1 - a) location of Caltanissetta town; b) location of the Santa Barbara mud volcano area; c) geological map of the Santa Barbara mud volcano area (extracted from the Geological Map of Italy 1:50000, F. 631- Caltanissetta, ISPRA), d) geo-referenced grid obtained through GNSS survey, with location of seismic noise sampling sites (dots) and MASW survey (yellow line): the red dots highlight the sampling points used for obtain the seismic impedance contrast sections (an alphanumeric reference was used to name HVSR samplings).