The Physics of the Plasma Universe by Anthony Peratt describes magma as a plasma, a medium containing moving charges. So we should expect volcanoes not only to exhibit electrical behavior but to have that behavior connected with the larger plasma environment, that is, to be elements in a larger electrical circuit.
Makes sense. I think I agree with the fixed timeline. But I also think you should be able to change anything that doesn't cause a paradox. An important event in someone else's life for example, leaving a note for yourself that the task is required in the future.