“…In addition to the electrokinetic effects studied here, SP anomalies in volcanic settings can also arise from electrochemical, thermoelectric and redox‐processes (e.g., Zlotnicki & Nishida, 2003) within hydrothermal systems and alteration zones and may need to be quantified separately. Furthermore, SP amplitudes are sensitive to the water‐saturation in soils above aquifers (Matsushima et al., 2017) and heterogeneities in subsurface resistivity (e.g., Ishido, 2004). A number of studies show that the streaming potential coupling coefficient depends not only on the water salinity but also on hydraulic rock properties, temperature, pore water conductivity and EDL properties (e.g., Ishido, 2004; Jouniaux & Pozzi, 1995; Jouniaux et al., 2000; Revil, Saracco et al., 2003).…”