▁Vol can ic ▁er u ptions ▁ ▁There ▁are ▁three ▁V E I - 7 ▁vol cano es ▁in ▁Japan . ▁These ▁are ▁the ▁A ira ▁Cal der a , ▁K ikai ▁Cal der a ▁and ▁A so ▁Cal der a . ▁▁ ▁Mount ▁A so ▁is ▁the ▁largest ▁active ▁vol cano ▁in ▁Japan . ▁Mount ▁A so ▁had ▁four ▁er u ptions ▁ 3 0 0 , 0 0 0 ▁to ▁ 9 0 , 0 0 0 ▁years ▁ago . ▁It ▁em itted ▁huge ▁amounts ▁of ▁vol can ic ▁ash ▁that ▁covered ▁all ▁of ▁Ky ush u ▁and ▁up ▁to ▁Yam ag uch i ▁Pref ect ure . ▁ ▁Earth qu akes ▁Japan ▁has ▁had ▁a ▁long ▁history ▁of ▁earth qu ake ▁cat ast rop he ▁and ▁se ism ic ▁activity . ▁In ▁the ▁past ▁twenty ▁years , ▁the ▁most ▁severe ▁earth qu ake ▁that ▁occurred ▁was ▁the ▁ 2 0 1 1 ▁T oh oku ▁earth qu ake ▁and ▁t sun ami . ▁ ▁'' ▁ ▁List ▁of ▁recent ▁earth qu akes ▁in ▁Japan ▁ ▁M ud sl ides ▁ ▁A ▁mud slide , ▁or ▁mud flow , ▁occurs ▁when ▁rocks , ▁sand , ▁and ▁earth ▁are ▁lo os ened ▁and ▁fall ▁from ▁hills ▁and ▁mountains ▁due ▁to ▁earth qu ake , ▁rain ▁or ▁snow . ▁In ▁Japan , ▁over ▁two - third s ▁of ▁the ▁land ▁is ▁mountain ous ▁and ▁therefore ▁pr one ▁to ▁mud sl ides . ▁ ▁Major ▁mud slide ▁events ▁ ▁Japan ▁has ▁experienced ▁several ▁major