Aso-Kuju National Park
Features of Sunasenri
Sunasenri ga hama is a crater floor covered with volcanic ash. The area is dotted with volcanic ash deposits and masses of hardened magma called “volcanic bombs.” The size of these volcanic bombs can vary from several centimeters to tens of centimeters, some even measuring more than 1 m in diameter, and can be seen distributed across the rugged terrain of the Sunasenri ga hama.
The terrain of the Sunasenri ga hama is 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 from the heat and pressure of a pyroclastic flow). Volcanic ash and pumice fragments discharged from the nearby active crater are distributed over Sunasenri ga hama, creating an ever-changing landscape. During an eruption, ash fall can dramatically decrease visibility and obscure the view.
Sunasenri ga hama is a barren landscape. The area is subject to high steam levels and volcanic gases, such as hydrogen sulfide and carbon dioxide. These gases are constantly emitted from the Nakadake crater, fumaroles or vents, and from hot spring sources. The hazardous gases create an environment in which few plants can grow. Visitors are strongly advised to stay on the wooden walkway.