The Shinzan Lava Dome, formed by the eruption in 1801, has a diameter of 300 m and a relative height of 70 m. Also known as Kyōwadake, Shinzan Peak’s estimated volume is 900,000 m³, and the total volume of ejected material (including volcanic ash) is estimated at approximately 1,025,000 m³.
There are vertical joints at the summit of the mountain, and cracks have developed east-west with a maximum width of more than 10 m and a length of approximately 100 m.

Volcanic bombs are scattered near the crater. These are masses of volcanic rock that partially cooled as they flew from the volcano’s crater. As the outside cools and the inside remains hot, the gas inside can expand and form cracks in the surface. Volcanic bombs with a cracked surface like this are known as breadcrust bombs.
The largest volcanic bomb, located next to the main shrine of Mt. Chokai Ōmonoimi Shrine, weighs 300 tons, which tells us how intense the eruption was.