“…Relatively recently, various remote sensing techniques have allowed large mountainous areas to be rapidly examined [ Metternicht et al , 2005] and diverse geophysical methods have been used to investigate unstable and adjoining stable rock at depth [ McCann and Forster , 1990; Hack , 2000]. As examples, geoelectrical, electromagnetic, seismic refraction, and surface wave surveys have supplied valuable information on the spatial variations of electrical resistivity and seismic velocity [ Bruno and Marillier , 2000; Cummings , 2000; Havenith et al , 2000; Jongmans et al , 2000; Mauritsch et al , 2000; Schmutz et al , 2000; Dussauge‐Peisser et al , 2003; Meric et al , 2005; Brückl and Brückl , 2006; Godio et al , 2006; Heincke et al , 2006b] and high‐resolution seismic reflection and ground‐penetrating radar (georadar or GPR) studies have yielded accurate subsurface images of active fractures and faults [ Bruno and Marillier , 2000; Dussauge‐Peisser et al , 2003; Heincke et al , 2005, 2006a; Spillmann et al , 2007]. …”