Famous for telling reporters that being on the mountain was like "standing next to a dynamite keg and the fuse is lit", Johnston had been among the first volcanologists at the volcano when eruptive signs appeared, and shortly after was named the head of volcanic gas monitoring. He and several other volcanologists prevented people from being near the volcano during the few months of pre-eruptive activity, and successfully fought pressure to re-open the area. Their work kept the death toll at a few tens of individuals, instead of the thousands who possibly could have been killed had the region not been sealed off.