GNGTS 2013 - Atti del 32° Convegno Nazionale

improving some of the prototype electronics, and in particular the low-noise circuitry, the performance of the new sensor to be very close or to out-perform the acquisition system employing conventional geophones. This is expected at the lowest frequencies below the geophone natural frequency, where the sensitivity of the standard geophone declines sharply, unlike the new prototype. Further measurements and manufacturing improvements are ongoing. We expect possible drawbacks due to temperature changes between the sensor and the vibrating surface, because in principle these changes could affect the sound speed and, consequently, the observed time shifts. Fortunately, our early tests show that such a phenomenon is barely observable, when temperature changes are not extreme. Systematic laboratory and field tests are needed (and planned) to quantify precisely this effect. Conclusions. Uncoupled acoustic sensors have relevant potential applications both for active seismic on land and for seismological recording. In the first case, a faster and cheaper data acquisition is envisaged, as well as a reduction of signal distortions due to coupling with loose grounds (see e.g. Robinson and Husseini, 1982, among others). In the second case, the direct recording of the displacement, instead of velocity or acceleration, may provide more accurate data for estimating earthquakes’ magnitude. Acknowledgements. Our work was partially supported by the Grant n. 11-OIL1638-04 in the NSTIP Program by KACST, Riyadh, Saudi Arabia. We thank Stefano Gustin (Microsum) for his contribution to the prototype development, and Luca Baradello, Daniel Nieto, Lorenzo Petronio and Franco Zgauc (OGS) for their valuable help. References Poggiagliolmi E., Vesnaver A., Nieto D. and Baradello L.; 2012: The application of uncoupled sensors to seismic exploration, Expanded Abstracts, SEG/KOC Workshop on Global Single Sensor Acquisition, Kuwait City (Kuwait). Poggiagliolmi E., Vesnaver A., Nieto D. and Baradello L.; 2013: An uncoupled acoustic sensor for land seismic acquisition, 75th EAGE Meeting, Extended Abstracts, London (United Kingdom), We 04 16. Ponton F., Di Bartolomeo P., A. Govoni and D. Zuliani; 2002: Seismometer calibration at OGS, XXVIII General Assembly of the European Seismological Commission, University of Genoa, September 2-8 2002. Robinson D. K. and Husseini M. I.; 1982: Technique for reflection prospecting in the Rub’ Al-Khali. Geophysics 18, 54-69. 80 GNGTS 2013 S essione 3.1