° F ) ▁and ▁the ▁formation ▁of ▁fro st ▁is ▁frequent ▁during ▁the ▁dry ▁season . ▁The ▁peak ▁is ▁host ▁to ▁a ▁large ▁installation ▁of ▁broadcast ▁to wers . ▁ ▁Description ▁De ▁Bo er ▁et ▁al . ▁were ▁the ▁first ▁to ▁show ▁that ▁El ▁Bar ú ▁vol cano ▁is ▁active ▁and ▁part ▁of ▁the ▁extension ▁of ▁the ▁Central ▁American ▁Vol can ic ▁Arc ▁in ▁Pan ama . ▁ ▁Further ▁detailed ▁work ▁on ▁the ▁ge och em istry ▁of ▁the ▁la vas ▁from ▁El ▁Bar ú ▁and ▁other ▁vol cano es ▁in ▁Pan ama ▁was ▁completed ▁by ▁Def ant ▁et ▁al . ▁They ▁subst anti ated , ▁based ▁on ▁ge och em istry , ▁that ▁the ▁la vas ▁were ▁derived ▁by ▁sub du ction ▁( calc - alk al ine ). ▁ ▁Rad i ometric ▁dates ▁also ▁showed ▁that ▁the ▁vol can ism ▁falls ▁into ▁two ▁groups ▁that ▁range ▁from ▁ 2 0 ▁million ▁years ▁to ▁recent . ▁They ▁also ▁showed ▁that ▁the ▁young est ▁vol can ism ▁consists ▁primarily ▁of ▁ad ak ites ▁( partial ▁mel ts ▁from ▁the ▁sub duct ed ▁sl ab ) ▁whereas ▁the ▁older ▁vol can ism ▁is ▁normal ▁calc - alk al ine ▁la vas . ▁ ▁US GS ▁Vol cano - H az ards ▁Ass ess ment ▁Study ▁In ▁ 2 0 0 6 , ▁an ▁earth qu ake ▁sw arm ▁was ▁registered ▁in ▁the ▁Vol c án ▁Bar ú ▁area . ▁This ▁was ▁not ▁the ▁first ▁one ; ▁research ers ▁c ite ▁at ▁least ▁three ▁other