“…In many cases, detecting and monitoring the presence or movement of fluids within such systems from multimodal signal sensing and imaging are a primary objective for several reasons, and require accurate knowledge of the structure holding or confining the fluids. In the Earth sciences for instance, accurate characterization of material heterogeneity and its influence on fluid flow or storage in subterranean reservoirs is of crucial importance in a wide range of contemporary issues including the use of groundwater resources, volcano and earthquake monitoring, methane storage in wetlands, carbon dioxide sequestration and efficient extraction of fossil fuels and landfill methane [e.g., Beckwith and Baird , 2001; Hertrich and Yaramanci , 2002; Binley et al , 2002; Gedney et al , 2004; Roecker et al , 2004; Comas et al , 2005; Chen et al , 2006; Alpak et al , 2004, 2008; Bedrosian et al , 2007]. (A glossary of some common geophysical terms is included and their first appearance is in italics).…”