Elements in the media made the event controversial. They suggested that the expedition leader, geologist Stanley Williams, who survived along with four others, had ignored safety procedures. A prediction had been made three days before the eruption, based on B-Type activity seen on a seismograph. Seismic B-types had been used successfully to predict eruptions on other volcanoes. However, the prediction was based simply on the one seismographic printout viewed in the light of previous history of Galeras, without any additional scientific measurements showing any serious activity within the volcano.