▁Indian ▁R idge ▁( SE IR , ▁between ▁the ▁Ind o - Austral ian ▁and ▁Ant ar ctic ▁pl ates ) ▁ 6 0   mm / yr . ▁ ▁The ▁SE IR ▁has ▁the ▁highest ▁spread ing ▁rates ▁at ▁the ▁R T J , ▁and , ▁while ▁now ▁considered ▁an ▁intermediate ▁spread ing ▁centre , ▁it ▁was ▁a ▁fast ▁spread ing ▁r idge ▁between ▁anom al ies ▁ 3 1 ▁and ▁ 2 2 , ▁with ▁a ▁rate ▁of ▁ 1 1 0   km / my r ▁at ▁anom aly ▁ 2 8 . ▁ ▁The ▁spread ing ▁rate ▁is ▁similar ▁in ▁the ▁C IR ▁but ▁slower ▁and ▁the ▁r idge ▁has ▁a ▁more ▁complex ▁geometry . ▁ ▁The ▁SW IR ▁has ▁ult ra - slow ▁spread ing ▁rates , ▁a ▁rough ▁top ography , ▁and ▁great ▁number ▁of ▁large ▁offset ▁f ract ure ▁zones . ▁ ▁All ▁three ▁boundaries ▁are ▁themselves ▁inter se cted ▁by ▁diff use ▁boundaries : ▁the ▁C IR ▁is ▁inter se cted ▁by ▁the ▁Indian – Cap ric orn ▁boundary ; ▁the ▁SE IR ▁by ▁the ▁Cap ric orn – Austral ian ▁boundary ; ▁and ▁the ▁SW IR ▁by ▁the ▁N ub ian – S om al ian ▁boundary . ▁ ▁For ▁example , ▁the ▁East ▁African ▁R ift ▁div ides ▁Africa ▁into ▁the ▁N ub ian ▁and ▁Som al ian ▁pl ates . ▁ ▁These ▁pl ates ▁conver ge ▁in ▁the ▁southern ▁part ▁of ▁the ▁r ift ▁valley ▁( 2   mm / yr )