Currently,　laser-induced　structural　modifications　in　optical　materials　have　been　an　active　field　of　research.　In　this　paper,　we　reported　structural　modifications　in　the　bulk　of　sapphire　due　to　picosecond　(ps)　laser　filamentation　and　analyzed　the　ionization　dynamics　of　the　filamentation.　Numerical　simulations　uncovered　that　the　high-intensity　ps　laser　pulses　generate　plasma　through　multi-photon　and　avalanche　ionizations　that　leads　to　the　creation　of　two　distinct　types　of　structural　changes　in　the　material.　The　experimental　bulk　modifications　consist　of　a　void　like　structures　surrounded　by　cracks　which　are　followed　by　a　submicrometer　filamentary　track.　By　increasing　laser　energy,　the　length　of　the　damage　and　filamentary　track　appeared　to　increase.　In　addition,　the　transverse　diameter　of　the　damage　zone　increased　due　to　the　electron　plasma　produced　by　avalanche　ionizations,　but　no　increase　in　the　filamentary　zone　diameter　was　observed　with　increasing　laser　energy.