to these reflectors changed over time as the domes deformed. Glicken monitored the volcano for two weeks, taking shelter in a trailer at the Coldwater II site located a little more than northwest of the volcano. On May 18, 1980, after working for six days straight, Glicken took the day off to attend an interview for his graduate work with his professor, Richard V. Fisher, in Mammoth Lakes, California. His research adviser and mentor David A. Johnston replaced him at his post, despite expressing concerns about its safety given indications of mobile magma within the volcano. After a magnitude 5.1 earthquake centered directly below the north slope triggered that part of the volcano to slide at 8:32 a.m., Mount St. Helens erupted. Johnston was killed after he was enveloped by swift pyroclastic flows that traveled down the mountain's flanks at near supersonic speeds. After the eruption, Glicken went to Toutle High School, the center for relief efforts, where he joined Air Force Reserve Rescue Squadron officials in a helicopter to look for Johnston or any sign of his post. Despite searching with three separate crews over a span of nearly six hours, Glicken found no trace. He attempted to enlist a fourth helicopter crew to aid his search, but they declined, fearing dangerous conditions. In his distraught state, Glicken refused to accept Johnston's death, and had to be comforted by Swanson before calming down. In mid-1980, after the May eruption, USGS Survey scientists decided to establish the David A. Johnston Cascades Volcano Observatory (CVO) in Vancouver, intending to closely monitor volcanoes in Oregon, Washington, and Idaho. Glicken returned to St. Helens to analyze the remains of the volcano's lateral blast. However, as other CVO employees had already commenced their research at the mountain, Glicken's offer to help USGS on his own was declined by senior scientists. Instead, he found work with newly appointed Survey employee Barry Voight, a specialist in landslides. Under Voight's guidance, Glicken absorbed himself in his work, motivated to earn a job at the Survey, and to relieve some of his anguish over Johnston's death. Glicken and a team of geologists mapped the debris field left over from St. Helens's structural collapse, which consisted of roughly a quarter of the mass of the volcano. Through extensive, meticulous analysis, the team traced the origins and the means of movement of each piece of debris, ranging from blocks in