Geonics EM31 survey for sand and gravelPublished February 13, 2017 at dimensions 640 × 478 in Request to Write for SeismicRental.com. Next → https://seismicrental.com/files/2012/01/Geonics-EM31-survey-for-sand-and-gravel.jpg https://seismicrental.com/files/2012/01/Geonics-EM38-Agricultural-Geophysics.jpg