▁putting ▁at ▁risk ▁population ▁and ▁cost ly ▁infrastr ucture ▁in ▁the ▁areas ▁surrounding ▁the ▁vol cano . ▁Typ ical ▁events ▁during ▁such ▁vol can ic ▁episodes ▁include ▁py ro cl astic ▁flows , ▁super - he ated ▁gas ▁clouds ▁rapidly ▁desc ending ▁the ▁vol cano ' s ▁east ▁fl ank , ▁conce iv ably ▁reaching ▁as ▁far ▁as ▁Bo qu ete , ▁Al to ▁Bo qu ete , ▁and ▁the ▁Cal der a ▁River , ▁and ▁fall out ▁of ▁ash ▁and ▁other ▁particles ▁r anging ▁in ▁size ▁from ▁dust ▁to ▁ 1 - meter ▁blocks , ▁known ▁as ▁te ph ra , ▁causing ▁fires , ▁roof ▁col laps es , ▁water ▁cont am ination , ▁c rop ▁damage ▁and ▁eye ▁and ▁lung ▁ir rit ation , ▁especially ▁among ▁el ders ▁and ▁inf ants . ▁A ▁third ▁type ▁of ▁event , ▁mud ▁and ▁de br is ▁flows , ▁known ▁as ▁la h ars , ▁create ▁land sl ides , ▁ob struct ▁rivers ▁courses , ▁and ▁could ▁have ▁long - term ▁effects ▁in ▁the ▁zone . ▁ ▁The ▁sever ity ▁of ▁these ▁events ▁is ▁directly ▁related ▁to ▁the ▁la va ▁flows ▁and ▁their ▁interaction ▁with ▁under ground ▁water ▁depos its . ▁ ▁A ▁compreh ensive ▁set ▁of ▁maps ▁is ▁included ▁with ▁the ▁study , ▁clearly ▁showing ▁the ▁most ▁likely ▁affected ▁areas ▁in ▁Bo qu ete , ▁Vol c án , ▁B amb ito ▁and ▁other ▁towns ▁in ▁vic inity ▁of ▁the ▁Vol c án ▁Bar ú . ▁The ▁study ▁recomm ends ▁local ▁authorities ▁should ▁make