Kirishima Remains Active – Dangerous Pyroclastic Flows at Shinmoe-dake
Kagoshima, July 8, 2025 – The Shinmoe-dake crater, part of Japan’s Kirishima volcanic complex on Kyushu, continues to show intense volcanic activity. Ash plumes are rising several thousand meters into the sky, and multiple pyroclastic flows have been observed. These deadly currents pose a serious threat to anyone who enters the restricted zone around the volcano.
Pyroclastic Flows – Virtually Unsurvivable
Pyroclastic flows are fast-moving clouds of superheated gas, fine ash, and rock fragments. They race down volcanic slopes on a cushion of gas, often with little to no warning or sound. Depending on the steepness of the slope and the eruption’s intensity, they can travel at incredible speeds, leaving little chance for escape.
These flows typically form in one of three ways: the collapse of a large Plinian eruption column, the breakdown of a lava dome or the front of a viscous lava flow, or through lateral explosions. In addition to their speed, pyroclastic flows are extremely hot – often causing fatal burns not only to the skin but also to the lungs, leading to death by asphyxiation.
As such, pyroclastic flows are among the most dangerous hazards associated with volcanoes. To protect the public, a 3-kilometre exclusion zone has been established around Shinmoe-dake. The Japan Meteorological Agency (JMA) estimates that the current flows can travel up to 2 kilometres, though significantly greater distances are possible during stronger eruptions. Recent photos from Sunday show a glowing cloud extending all the way to the base of the cone.
Activity Ongoing Since Late June – Pyroclastic Flows First Documented on Sunday
Shinmoe-dake entered its current active phase on June 22, with activity steadily intensifying since. On Saturday, ash plumes rose as high as 5,000 metres above the crater. The first pyroclastic flows were documented on Sunday afternoon, followed by additional flows on Monday. Poor weather has limited visibility today, but a webcam image from this morning suggests that another pyroclastic flow may have occurred.
Visitors are strongly urged to heed all warnings and avoid entering the restricted area. A safe and panoramic view of the volcano can be had from the 1,700-metre-high Karakuni-dake, the tallest peak within the Kirishima complex. Located about 3 kilometres northeast of Shinmoe-dake, it is still within range of modern drones—though their operation is, of course, legally limited to visual line-of-sight.
Signs the Eruption May Be Easing
Recent geophysical data show a slight contraction of the crater, likely due to increased ash emissions. It appears that less magma is currently rising from depth than is being expelled at the surface. This could indicate that the current eruptive phase may be nearing its end.