Task: Question Answering
Input (English): Passage: In the years following the eruption, despite earning rapid fame and opportunities to research internationally in Japan, New Zealand, and Guadeloupe, Glicken still failed to obtain a job at USGS. Senior employees at the Survey found his behavioral oddities unsettling. Activity at Mount St. Helens diminished, prompting USGS to reduce CVO's budget and contemplate closing the station. He continued helping the Survey until 1989, also serving as an assistant researcher at the University of California at Santa Barbara.From 1989 to 1991, Glicken continued his volcanological studies in Japan as a postdoctoral fellow at the Earthquake Research Institute of the University of Tokyo, supported by grants from the U.S. National Science Foundation. Later, while a research professor and translator at Tokyo Metropolitan University, Glicken became involved with research at Mount Unzen. The volcano had recently resumed eruptive activity in November 1990, after being dormant for 198 years. In the months after its first activity, it erupted sporadically, and the government evacuated its vicinity near the end of May 1991. On June 2, 1991, Glicken visited the mountain with Katia and Maurice Krafft. The three entered a danger zone near the base of the volcano the following day, assuming that any potentially hazardous pyroclastic flows would follow a turn in the landscape and safely bypass them. Later that day, a lava dome collapsed, sending a large flow down the valley at 60 miles per hour (97 km/h). The current reached the turn before separating into two parts, and the upper, hotter part swiftly overcame the volcanologists' post, killing them upon impact. In total, 41 or 42 people died in the incident, including press members who had been watching the volcanologists. The volcano burned down 390 houses, and the remains of the flow extended 2.5 miles (4 km) in length. Glicken's remains were found four days later, and were cremated according to his parents' wishes. To date, Glicken and Johnston are the only American volcanologists known to have been killed by a volcanic eruption. 
Question: What is the last name of the American volcanologist that has died along with the man continued his volcanological studies in Japan?
Output (English): Johnston.