Mt. Asama-yama (#43 of the 100 Famous Mountains in Japan)
What is one hundred mountains in Japan?: http://beauty-of-japan.com/article/japan-one-hundred-best-mountains/
Asama-yama is one of the 100 Famous Mountains and has the illustrious reputation of being the only one presently closed to climbers. (Iwate-san in Tohoku and Meakan-dake in Hokkaido sometimes share this distinction). It has erupted violently several times over history and since 1957 has been deemed to be too unstable for the general public to climb (the original 4km approach limit relaxed to 3km in 1997). This doesn't stop people from completing their 100 mountains by climbing Asama-san but, if you do decide to do it against this advice, be aware that you are on your own should you get into difficulties Ironically, it is not the volcanic activity that often proves dangerous but the weather. In April 1999 three Japanese hikers got lost on the mountain in a sudden storm and died of exposure. Unless you are a dedicated '100 mountains peak-bagger' there is no point bucking the system anyway - this is one of those mountains best appreciated from a distance and this hike provides a great view of the peak from Kurofu-yama.
Asama-yama is actually three volcanoes piled on top of each other. The first of these was the Kurofu volcano, centred 400m west of the present peak and accounting for 70% of the present mass of the mountain. This is believed to have been 400m higher than the current peak of Asama-yama. Approximately 30,000 years ago a new eruption to the east created what has been named the Hotokeiwa volcano. Subsequently, about 13,000 years ago, a third huge eruption created the Maekake volcano and produced the present-day 200m deep crater. There have been 71 recorded eruptions of Asama, some were nothing more than gaseous explosions but others, such as the 1783 eruption when 1600 people in the villages below the mountain were killed, were huge disasters. This 1783 catastrophe is the worst in Japanese history. Asama is seen as being one of Japan's most active volcanoes. In recent times it has erupted in 1973, explosively in 1983, had a 3 month 'episode from September 2004, and in February of 2008 it erupted again sending out clouds of ash as far as Tokyo.
- Karuizawa, Kitasaku District, Nagano