/ 2 0 1 2 ▁when ▁there ▁was ▁an ▁increased ▁se ism ic ▁activity ▁and ▁probably ▁vol can ic ▁activity ▁on ▁the ▁cal der a ▁floor ▁ ▁( there ▁is ▁no ▁exact ▁information ▁about ▁the ▁cal der a ▁floor ▁at ▁that ▁time ). ▁In ▁ 2 0 1 4 ▁the ▁same ▁research ▁team ▁carried ▁out ▁a ▁further ▁expedition ▁into ▁the ▁cal der a ▁and ▁set ▁a ▁new ▁record : ▁over ▁ 1 2 ▁days ▁the ▁investig ations ▁of ▁ 2 0 1 3 ▁were ▁continued . ▁ ▁Mon itor ing ▁▁ ▁Indones ia ' s ▁population ▁has ▁been ▁increasing ▁rapidly ▁since ▁the ▁ 1 8 1 5 ▁er u ption . ▁In ▁ 2 0 1 0 , ▁the ▁population ▁of ▁the ▁country ▁reached ▁ 2 3 8 ▁million ▁people , ▁of ▁which ▁ 5 7 . 5 % ▁ ▁concentr ated ▁on ▁the ▁island ▁of ▁Java . ▁An ▁event ▁as ▁significant ▁as ▁the ▁ 1 8 1 5 ▁er u ption ▁would ▁impact ▁about ▁eight ▁million ▁people . ▁ ▁Se ism ic ▁activity ▁in ▁Indones ia ▁is ▁monitor ed ▁by ▁the ▁Director ate ▁of ▁Vol can ology ▁and ▁Ge ological ▁Haz ard ▁Mit ig ation ▁with ▁the ▁monitoring ▁post ▁for ▁Mount ▁Tamb ora ▁located ▁at ▁D oro ▁Pet i ▁village . ▁They ▁focus ▁on ▁se ism ic ▁and ▁t ect onic ▁activity ▁by ▁using ▁a ▁se ism ograph . ▁There ▁has ▁been ▁no ▁significant ▁increase ▁in ▁se ism ic ▁activity ▁since ▁the ▁ 1 8 8 0 ▁er u ption . ▁Mon