Semeru Eruption This Morning Spews Ash 800 Meters High

Lumajang: Mount Semeru again showed increased volcanic activity on Tuesday morning, November 25, 2025. The eruption was recorded at 4:45 a.m. Western Indonesian Time (WIB), accompanied by a column of ash approximately 800 meters high above the summit, or approximately 4,476 meters above sea level.

This report was submitted by Mukdas Sofian, an officer at the Semeru Volcano Observation Post on Mount Sawur, who directly monitored the activity from the monitoring post. The ash column was observed to be white to gray in color, moderate in intensity, and tilted northward.

Eruptive activity was also recorded on a seismogram with a maximum amplitude of 22 millimeters and a duration of approximately 1 minute and 59 seconds. As of the report's publication, the eruption was still ongoing.

According to Mukdas Sofian, the increased activity at Semeru was detected early on through a continuous visual and instrumental monitoring system.

"We ensure all monitoring data is updated in real time. We immediately report any changes, no matter how small, to support mitigation measures," he said in a text message on Tuesday morning, November 25, 2025.

He emphasized that Mount Semeru's current status remains at Level IV (Alert). All residents in disaster-prone areas are asked to increase their vigilance and comply with official recommendations from authorities.

"The status remains at Level IV, or Alert. We urge the public to strictly comply with all official recommendations. This is not about distance on the map, but about safety," Mukdas emphasized.

Under this status, the public is prohibited from carrying out activities in the southeastern sector along the Besuk Kobokan stream up to a distance of 20 kilometers from the summit. Furthermore, areas within an 8-kilometer radius of the crater must be evacuated due to the potential for ejection of incandescent rocks.

Residents living near rivers that originate at the summit of Mount Semeru, such as Besuk Kobokan, Besuk Bang, Besuk Kembar, Besuk Sat, and their tributaries, are advised to be vigilant for potential pyroclastic flows, lava flows, and lahars, which can occur at any time, especially during rain.

Meanwhile, mitigation efforts continue to be strengthened. Several measures are being prepared, including emergency post readiness, evacuation route checks, and cross-agency coordination to ensure any changes in volcanic activity can be responded to quickly and measurably.

Mukdas Sofian confirmed that the monitoring team continues to operate 24/7. This is to ensure the public receives accurate and up-to-date information.

"We work 24/7. Mount Semeru is alive, and our job is to ensure the public receives the most accurate information so they can take safe measures," said Mukdas.