▁this ▁stage ; ▁er upt ed ▁from ▁an ▁unknown ▁vent , ▁they ▁lack ▁am ph ib oles . ▁The ▁total ▁volume ▁is ▁, ▁indicating ▁a ▁flux ▁rate ▁of ▁. ▁A ▁fl ank ▁collapse , ▁possibly ▁triggered ▁by ▁a ▁large ▁earth qu ake , ▁occurred ▁during ▁this ▁stage . ▁ ▁The ▁third ▁stage ▁is ▁the ▁C um bre ▁Neg ra ▁stage , ▁named ▁after ▁the ▁western most ▁sum mit ▁and ▁principal ▁vent ▁of ▁this ▁stage , ▁Cer ro ▁C um bre ▁Neg ra ▁( ). ▁The ▁time ▁course ▁of ▁its ▁activity ▁is ▁less ▁defined ▁than ▁the ▁previous ▁two ▁stages ; ▁it ▁may ▁have ▁occurred ▁between ▁ 1 – 0 . 4 7 ▁my a , ▁but ▁most ▁likely ▁ 0 . 6 – 0 . 5 ▁my a ▁based ▁on ▁pot ass ium – arg on ▁d ating . ▁Four ▁la va ▁flows ▁derived ▁from ▁the ▁main ▁vent , ▁all ▁less ▁than ▁one ▁kilomet re ▁long ▁and ▁ ▁th icker ▁than ▁previous ▁stages . ▁They ▁all ▁have ▁hyd r ation ▁r inds ▁but ▁no ▁native ▁sul fur ▁depos its . ▁This ▁stage ▁generated ▁A uc an qu il cha ' s ▁only ▁py ro cl astic ▁flow ▁during ▁a ▁la va ▁d ome ▁collapse ▁as ▁occurred ▁on ▁Mer api ▁in ▁Indones ia . ▁The ▁total ▁volume ▁of ▁this ▁stage ▁is ▁, ▁indicating ▁a ▁flux ▁rate ▁of ▁. ▁ ▁The ▁young est ▁stage , ▁known ▁as ▁Ang ulo , ▁last ed ▁from ▁ 0 . 6 6 ▁to ▁ 0 . 2 4 ▁my a