Table 4 Example titles of four representative articles for each cluster

— Ontake area in the summer, climbing season on the side of the town of Kiso, removal of a warning alert. (Y, July 2, 2019)

— To climb Mt. Ontake, regulations will again be established, starting today. (C, October 8, 2018)

— A warning alert for part of the Kurosawa-guchi route at Mt. Ontake’s ninth station will be removed today. (C, June 28, 2016)

— The town of Kiso decided to remove a warning alert for the Mt. Ontake trail from July 1 to October 16. (Sh, March 7, 2019)

— Volcanic eruption of Mt. Kusatsu-Shirane. Imperfect volcano evacuation plan in most towns, including Kusatsu-machi, Gunma. (M, January 26, 2018)

— There was a phreatic eruption at Mt. Kusatsu-Shirane. Evacuation plans are inadequate in two-thirds of all municipalities in volcanic areas. Kusatsu-machi was also undecided. Obligations have not been firmly followed. (N, January 25, 2018)

— Volcanic evacuation plans are created in 51 municipalities, and two-thirds of all plans are being considered. (C, June 24, 2017)

— Thirty percent of the municipalities in volcanic zones have produced volcanic evacuation plans. Many municipalities have been unable to keep up with the revised law. (A, January 28, 2018)

— Bereaved families completed a memorial climb on Mt. Ontake and commemorated the victims of the eruption. (N, July 24, 2017)

— The second anniversary of the Mt. Ontake eruption. Grieving families requested that a tombstone be built for the victims at a commemorative ceremony site. (Sh, September 28, 2016)

— The unveiling of the tombstone for the victims was conducted in the village of Otaki in Nagano Prefecture. (A, September 27, 2017)

— The Mt. Ontake executive committee that built the tombstone was dissolved. (Sh, June 27, 2019)

— The town of Kiso created an evacuation plan and added it to the Kiso’s disaster prevention plan. This is due to the obligation of the revised Act on Special Measures Concerning Active Volcanoes. (C, October 2, 2018)

— Nagano Prefecture announced the revised Nagano’s disaster prevention plan this year. The Volcanic Disaster Council’s role was stipulated. (Sh, December 23, 2015)

— The town of Kiso designed an evacuation plan in the case of an eruption. (Sh, October 3, 2018)

— The Mt. Ontake Volcanic Disaster Council decided to work out detailed evacuation and guidance procedures for hikers when the action plan was revised in FY2017. (Sh, March 22, 2017)

— An advanced team will go to Mt. Ontake tomorrow. (C, July 11, 2015)

— The volcanic eruption of Mt. Ontake. An advanced team will be sent tomorrow, Nagano-Gifu. (M, July 11, 2015)

— The volcanic eruption of Mt. Ontake. An advanced team will re-investigate tomorrow, and 44 members will be sent. Press release from the prefecture’s disaster countermeasures office. (Sh, July 11, 2015)

— To resume the search for missing persons, an advanced team will be sent to the summit of Mt. Ontake starting on July 7. (C, July 4, 2015)