The disclosure relates to a method of evaluating characteristics of an earth formation, comprising deploying a packer assembly in a borehole penetrating an earth formation, the packer assembly comprising an instrumented inflatable packer element including fiber optic sensors; inflating the instrumented inflatable packer elements; detecting, using the fiber optic sensors, events occurring in the earth formation; and transmitting data corresponding to the detected events to a surface processing system. The disclosure also relates to a packer element and a instrumented packer assembly system. The disclosure may enable to derive formation characteristic in several configurations such as a stress test or a hydraulic fracturing configuration.