▁May ▁and ▁in ▁Spain , ▁Portugal , ▁northern ▁Italy , ▁Austria , ▁and ▁southern ▁Germany ▁on ▁ 9 ▁May . ▁Irish ▁and ▁UK ▁air space ▁closed ▁again ▁on ▁ 1 6 ▁May ▁and ▁re open ed ▁on ▁ 1 7 ▁May . ▁ ▁The ▁er u ption ▁occurred ▁beneath ▁gla cial ▁ice . ▁The ▁cold ▁water ▁from ▁the ▁mel ting ▁ice ▁ch illed ▁the ▁la va ▁quickly , ▁causing ▁it ▁to ▁fragment ▁into ▁very ▁small ▁particles ▁of ▁glass ▁( sil ica ) ▁and ▁ash , ▁which ▁were ▁carried ▁into ▁the ▁er u ption ▁pl ume . ▁The ▁extremely ▁fine ▁ash ▁particles ▁and ▁the ▁large ▁volume ▁of ▁steam ▁from ▁the ▁gla cial ▁m elt water ▁sent ▁an ▁ash ▁pl ume ▁ha z ard ous ▁to ▁aircraft ▁rapidly ▁high ▁into ▁the ▁upper ▁atmosphere . ▁The ▁presence ▁and ▁location ▁of ▁the ▁pl ume ▁dep ended ▁upon ▁the ▁state ▁of ▁the ▁er u ption ▁and ▁the ▁wind s . ▁The ▁large ▁amount ▁of ▁gla cial ▁m elt water ▁flow ing ▁into ▁the ▁er u ption ▁vent ▁made ▁this ▁er u ption ▁so ▁explos ive ▁that ▁it ▁e ject ed ▁its ▁ash ▁pl ume ▁directly ▁into ▁the ▁jet ▁stream , ▁which ▁was ▁unus ually ▁stable ▁and ▁south - e aster ly . ▁The ▁ash ▁was ▁then ▁carried ▁over ▁Europe ▁into ▁some ▁of ▁the ▁bus iest ▁air space ▁in ▁the ▁world . ▁ ▁The ▁International ▁Air ▁Transport ▁Association ▁( I ATA ) ▁estimated ▁that ▁the ▁air line ▁industry ▁world wide ▁would ▁lose ▁ ▁( , ▁) ▁a ▁day ▁during