Mount Semeru in Lumajang, East Java, experienced six eruptions between early Thursday and noon, April 17, 2025, with the highest volcanic ash column reaching 1,000 meters above the summit during the 9:17 AM local time eruption. The more severe alert levels are Alert and Danger.The Level II (Caution) status mandates that communities and visitors avoid all activity in the southeast sector along Besuk Kobokan within 8 kilometers of the peak (eruption center). Beyond this, no activity is permitted within 500 meters of the riverbank along Besuk Kobokan due to the risk of hot clouds and lava flow extending up to 13 kilometers from the summit. A 3-kilometer radius around the crater/peak is also off-limits due to the danger of pyroclastic fall. "Furthermore, communities and visitors must remain vigilant for potential hot clouds, lava flows, and mudflows along streams originating from Mount Semeru's peak, particularly Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as potential mudflows in tributaries of Besuk Kobokan."