Multimodal tool jar

Methods and apparatus for alleviating a stuck condition of a tool string, including using a jarring assembly to collide a plurality of impact surfaces together. The collision results in at least a shock wave inducing i) translational motion along the longitudinal axis of the tool string, and ii) motion in at least one other degree of freedom sufficient to alleviate the stuck condition of the tool string, which may be at least one of: i) translational motion along an axis substantially normal to the longitudinal axis, and ii) rotational motion. Methods may include generating at least one test impact load using a jarring assembly; generating movement information from a sensor responsive to the at least one test impact load; and generating further impact loads using the jarring assembly in dependence upon the movement information.