Mt.Pinatubo

EileenDempsey

Luzon,PhilippineIslands

•  Stratovolcano•  Formedatasubduc?onzonewherethePhilippineMobileBeltisslidingovertheEurasianplatealongtheManilaTrench

•  Andesite,Dacite

Tectonic setting of the Philippine Islands.

Eventsleadingtoerup?on

•  7.7magnitudeearthquake•  Emissionofsteamandgases•  Smalllandslides•  Asuccessionofearthquakesincreasinginmagnitude

•  Phrea?cerup?ons•  Smallerup?onscon?nuedalongwithmanyearthquakes

•  Smallmagma?cerup?ons

June7th,1991

•  ThePhilippineIns?tuteofVolcanologyandseismologyissuedanerup?onwarningaMerthefirstlargeexplosion– 7mtallashcolumn

•  Dailywarningsandupdatesweredeliveredbynewspaper,radio,television,anddoortodoor

•  Forma?onofalavadomeatthesummit•  June12th‐erup?onsbecameincreasinglyintense,witherup?oncolumns,pyroclas?cflows,andtephra

•  Largetremors/earthquakes

•  1991June15therup?on‐– Pyroclas?cflows,ashdeposits,andlahars– Ultrapliniancolumn– 10billionmetrictonsofmagma– 100mthickpyroclas?cflows

– Typhoonrainscreatesmassivelahars– AshcouldcoveredallofcentralLuzon‐bringtotaldarkness

Tephrafallfrom1991erup?on

•  10?meslargerthanMt.St.Helens1980erup?on

•  800+peoplekilled

MajorCosts

•  Displacedpeople/families•  Ash+Typhoon=Roofcollapse•  furthercostswereincurredinconstruc?ngdikesanddamstocontrolthepost‐erup?onlahars

•  volumeoflavaandashinjectedsignificantquan??esofaerosolsanddustintothestratosphere

Currently…

•  Ac?vitycon?nuedonasmallerscalethroughAugust

•  By1992July,anewlavadomewasforming