In situ measurement of electrical resistivity of marine sediments, results from Cascadia Basin off Vancouver Island

Electrical properties of sediments encompass information about other linked physical properties, such as porosity and thermal conductivity. In situ measurements of electrical resistivity offer a cost- and time effective method for obtaining a comprehensive overview of near surface sediment physical properties. They also provide a quality check for in situ measurements of related sediment properties or for data obtained from sediment core analysis. sent results from the deployment of a sediment penetrating in situ probe which logs electrical resistivity of marine or limnic sediments up to 4 mbsf. Additionally, acceleration and pressure are recorded during sediment penetration. As the integration of acceleration delivers penetration depth with respect to time, a resistivity–depth profile can be derived. asurements presented were performed during cruise SO-149 in the Cascadia Basin and at the eastern flank of the Juan de Fuca Ridge. The in situ probe is attached to a Lister-type heat flow instrument; therefore simultaneous measurements of thermal and electrical resistivities are possible. Strongly influenced by porosity, both data sets show good correlation. Continuous recordings of electrical resistivity can be used to validate and supplement the thermal data, which is only measured in depth intervals of 30 cm. Comparison with other independent measurements such as porosity measured on sediment cores also confirm the correct operation of the probe.