Sezvazvakaita mune dzakawanda dzakapfuura St. Helens 'kuputika, izvi zvakagadzira lahars hombe (makomo anoputika emadhaka) uye mafashama emadhaka akaenderera mberi nekukanganisa matatu eaya mana mafashama emvura pagomo, uye ayo akatanga kufamba nekukurumidza se8: 50 am Lahars akafamba nekukurumidza semakiromita 90 paawa (140 km / h) vachiri pamusoro pegomo rinoputika asi zvishoma nezvishoma akaderera kusvika pamakiromita matatu paawa (4.8 km / h) pane zvikamu zvakaenzana uye zvakafara zvenzizi. Mafashama kubva kumaodzanyemba nekumabvazuva kwakapatsanuka aive nehuremu hwekongiri pavakamhanyira pasi nePine Fork, uye chikamu chavo cheSmith Creek kuRwizi rweLewis. Mabhiriji paRwizi rweLewis akaenderera mberi nekukwira kumusoro (makiromita 175,000) uye mafashama emadhaka akaenderera mberi nekukwira kumusoro.
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