Mount Semeru's Lahar Flood Tremors Recorded for Nearly Four Hours

The water level in the river has increased, so we urge the public to be careful when crossing the Regoyo River.

Lumajang, East Java (ANTARA) - Tremors from the lahar flood of Mount Semeru in Lumajang Regency, East Java, were recorded for almost four hours due to heavy rain that hit the highest mountain on the island of Java on Thursday.

“During the observation period on Thursday from 00:00 to 06:00 WIB, one lahar flood tremor was recorded with an amplitude of 17 mm, and the duration of the tremor was 13,304 seconds or 3 hours and 42 minutes,” said Officer at the Mount Semeru Observation Post, Sigit Rian Alfian, in a written report received in Lumajang.

In addition to the lahar flood tremors, during the last six hours, 17 eruption/ejection tremors were also recorded with an amplitude of 11-22 mm and a duration of 65-104 seconds, three rockfall tremors with an amplitude of 2-3 mm and a duration of 33-40 seconds, and one ash tremor with an amplitude of 6 mm and a duration of 51 seconds.

“Visually, the mountain was covered in fog. No crater smoke was observed. The weather was cloudy to rainy, with weak to strong winds blowing to the north and northeast,” he said.

Outside of this distance, he said, people should not carry out activities within 500 meters of the riverbank (river buffer zone) along Besuk Kobokan because it has the potential to be affected by the expansion of hot clouds and lava flows up to a distance of 17 kilometers from the peak.

“People are also prohibited from carrying out activities within a radius of 5 kilometers from the crater/peak of Mount Semeru, because they are at risk of being hit by flying rocks (incandescent material),” he said.

The public needs to be aware of the potential for hot clouds, lava flows, and lahar along the river/valley that originates at the peak of Mount Semeru, especially along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as the potential for lahar in small rivers that are tributaries of Besuk Kobokan.

Meanwhile, the Head of the Regional Disaster Management Agency (BPBD) of Lumajang, Isnugroho, said that his party received reports that the lahar flood of Mount Semeru occurred at night, but the conditions were still safe and did not overflow into residential areas.

“The water level in the river has certainly increased, so we urge the public to be careful when crossing the Regoyo River, especially residents in Dusun Sumberlangsep. Until Thursday morning, it had no impact on community activities, everything was running normally,” he said.