Mount Semeru again showed intense volcanic activity on Thursday (11/6/2026). Based on data from the Mount Semeru Observation Post, 18 eruptions were recorded within a six-hour timeframe, specifically from 06:00 to 12:00 WIB.
Observation Post officer, Sigit Rian Alfian, reported that the volcanic ash column reached a maximum height of 1,000 meters above the peak, or about 4,676 meters above sea level. The observed ash tended to be white to gray with thick intensity moving toward the southwest. This phenomenon was clearly recorded on the seismograph with a maximum amplitude of 22 mm and an eruption duration of 114 seconds.
In addition to eruption activity, officers also recorded material avalanche phenomena with a runout distance reaching 600 meters heading toward the southeast sector. This condition demands extra vigilance from residents around the mountain slopes.
To avoid unwanted risks, authorities strictly instructed the public not to conduct any activities within a 13-kilometer radius from the peak. In addition to the danger of pyroclastic flows, residents living along river basins originating from Mount Semeru are also advised to beware of secondary threats such as lava flows and cold lahar floods.
