HYOGO, May 13, 2026 (News On Japan) - A popular geological attraction in Toyooka known for its distinctive volcanic rock formations has reopened after being temporarily closed following a large-scale rock collapse.
Genbudo, designated as a national natural monument, was formed around 1.6 million years ago when magma from volcanic activity cooled and solidified into column-like structures.
The site had been closed since March 21st after a slope located about 35 meters above the cave collapsed on a large scale.
"The collapsed section measured roughly 10 meters wide and 6 meters high. Rather than rocks simply falling, it felt as though an entire wall had peeled away," a representative explained.
The facility has now fully reopened after safety measures, including the installation of protective barriers, were completed. Operators said more comprehensive countermeasures will be considered later based on the findings of expert investigations.
The park is home to five major cave formations — Genbudo, Seiryudo, Byakkodo, Minami Suzakudo and Kita Suzakudo — each displaying distinct patterns and colors in their columnar rock structures formed by volcanic activity around 1.6 million years ago. The site is widely regarded as one of Japan’s finest examples of columnar joints, where cooling magma contracted into remarkably regular hexagonal pillars.
The formations have also played an important role in the history of geology and geomagnetic research in Japan. Genbudo in particular became internationally known after studies of its magnetic properties contributed to research into geomagnetic reversals, helping scientists better understand shifts in the Earth’s magnetic field over geological time.
At the same time, the site continues to fascinate visitors beyond its scientific explanation. Many observers describe the towering stone columns as resembling giant plant fibers or petrified organic tissue rather than ordinary rock, with the almost artificial symmetry of the formations leaving a strong visual impression. The contrast between scientific interpretation and the emotional response experienced when standing before the cliffs has become part of the attraction itself.
Source: ABCTVnews
