Mount Semeru's Alert Level Downgraded, Caution Still Advised

TEMPO.CO, Bandung - The Geological Agency has lowered the alert level of Mount Semeru in Lumajang Regency, East Java, due to a decrease in the volcano’s activity. “As of July 15 at 15:00 WIB (Western Indonesia Time), Semeru’s alert level has been lowered from Level III (Siaga) to Level II (Waspada),” Head of the Volcanology and Geological Disaster Mitigation Center (PVMBG), Priatin Hadi Wijaya, said on Monday, July 15.

This change in status allows for some easing of restrictions on nearby communities. Previously, there was a 13-kilometer exclusion zone at level III. Now, the danger zone has been reduced to a 3-kilometer radius from the crater. However, activities in the Besuk Kobokan area, southeast of the volcano, are still restricted to within 8 kilometers.

“Beyond this distance, people are advised not to carry out activities within 500 meters of the river bank along Besuk Kobokan due to the risk of hot clouds and lava flows extending up to 13 kilometers from the summit,” Hadi underlined.

The Geological Agency further reported visual observations within the last week, between July 8-14, 2024. Researchers still saw gray-white smoke emissions reaching 100-900 meters above the crater and incandescent lava flows with a sliding distance of 300-1,000 meters towards Besuk Kobokan.

Additionally, instrumental monitoring detected 955 earthquake eruptions, 133 avalanche earthquakes, 58 gust earthquakes, 5 harmonic earthquakes, 1 local tectonic earthquake, and 48 distant tectonic earthquakes.

Tiltmeter monitoring data—a mountain deformation measuring tool that functions to detect the swelling or deflation of the body of a mountain—at the Argosuko Tiltmeter Station showed a horizontal deformation pattern. Continuous GPS monitoring data also showed changes between GPS station baselines, generally indicating distance shortening.

While eruptions, hot clouds, and lava avalanches persist, a decrease in deep volcanic earthquakes has been observed. The significant increase in eruption earthquakes suggests an increase in material reaching the surface and accumulating near the Jonggring Seloko crater.

“Then, from ambient noise seismic monitoring on Mount Semeru, it was concluded that there was no increase in stress or pressure on the body of the mountain,” said Hadi.

Therefore, the monitoring suggested a decrease in the immediate threat posed by Mount Semeru. However, the Geological Agency continued to closely monitor the volcano and urged residents to remain vigilant and follow official recommendations.

AHMAD FIKRI (BANDUNG)

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