The Nakadake Crater No. 4
The Nakadake peak of Mt. Aso was formed by a series of multiple eruptions. Today, Nakadake has seven craters located within a 1 km area, running north to south. Crater No. 4, in contrast to craters number 1 and 2, has not erupted in recent years. However, the entire crater area is constantly under surveillance to ensure the safety of visitors, and to enable large-scale volcanic research into disaster prevention measures.
The terrain around Crater No. 4 is barren and made up of volcanic rock: pumice, scoria (a pumice-like rock created by the hardening of gaseous basaltic magma), and welded tuff (a hardened rock created by the heat and pressure of a pyroclastic flow).
Even though Crater No. 4 is inactive, the level of sulfuric acid in the air from the remaining active crater areas is still high. Please do not step beyond the "No Entry" barriers.
The Fourth Crater
East side wall of the Fourth Crater
West side wall of the Fourth Crater
Sunasenri-ga-hama