Electrical resistivity tomography (ERT) is a well-established method of imaging the electrical conductivity structure of the subsurface. Electrical conductivity is a useful metric for understanding the subsurface, because it is governed geology, minerology, and geochemistry. ERT has been used characterize subsurface geologic structure, and to monitor the evolution of subsurface processes ranging from microbially induced mineral transformations to steam migration through unsaturated sediments. Such time-lapse imaging typically involves collecting data during the process of interested, and then processing the data to produce images days, weeks, or months after the process has occurred.