ossa ▁Airport ▁shut ▁down ▁operations ▁during ▁the ▁night ▁for ▁safety ▁pre ca utions . ▁ ▁An ▁er u ption ▁on ▁the ▁morning ▁of ▁ 1 3 ▁May ▁ 2 0 0 8 , ▁immediately ▁to ▁the ▁east ▁of ▁Et na ' s ▁sum mit ▁cr aters ▁was ▁accompanied ▁by ▁a ▁sw arm ▁of ▁more ▁than ▁ 2 0 0 ▁earth qu akes ▁and ▁significant ▁ground ▁de formation ▁in ▁the ▁sum mit ▁area . ▁The ▁er u ption ▁continued ▁at ▁a ▁slowly ▁dimin ishing ▁rate ▁for ▁ 4 1 7 ▁days , ▁until ▁ 6 ▁July ▁ 2 0 0 9 , ▁making ▁this ▁the ▁longest ▁fl ank ▁er u ption ▁of ▁Et na ▁since ▁the ▁ 1 9 9 1 – 1 9 9 3 ▁er u ption ▁that ▁last ed ▁ 4 7 3 ▁days . ▁Pre vious ▁er u ptions , ▁in ▁ 2 0 0 1 , ▁ 2 0 0 2 – 2 0 0 3 , ▁and ▁ 2 0 0 4 – 2 0 0 5 ▁had ▁last ed ▁ 3 ▁weeks , ▁ 3 ▁months , ▁and ▁ 6 ▁months , ▁respectively . ▁L ava ▁flows ▁advanced ▁ 6 . 5   km ▁during ▁the ▁first ▁few ▁days ▁of ▁this ▁er u ption ▁but ▁there after ▁st agn ated ▁at ▁many ▁minor ▁distances ▁from ▁the ▁v ents ; ▁during ▁the ▁last ▁months ▁of ▁the ▁er u ption ▁la va ▁rarely ▁advanced ▁more ▁than ▁ 1   km ▁down s lo pe . ▁ ▁Through ▁January ▁