Lumajang, East Java - Vibrations from the cold lava flood of Mount Semeru in Lumajang Regency, East Java, were recorded for more than 3 hours because heavy rain poured down the peak area of the highest mountain on Java Island, Sunday.
Mount Semeru Observation Post Officer Mukdas Sofian in his written report in Lumajang Regency stated that observations of Mount Semeru's seismic activity on March 3 2024 at 12.00-18.00 WIB showed that there was a flood vibration earthquake.
"Indeed, there was one flood shaking earthquake with an amplitude of 35 mm, and the earthquake lasted 10,819 seconds or more than 3 hours," he said in Lumajang, Sunday.
Apart from flood vibrations, Mount Semeru's activity also experienced 10 earthquake eruptions/eruptions with an amplitude of 11-22 mm, and an earthquake lasting 50-125 seconds, then 2 harmonic earthquakes with an amplitude of 2 -6 mm and the earthquake duration was 75-120 seconds.
"For visual observation, Mount Semeru was clearly visible until it was covered in 0-III fog. Crater smoke was not observed. The weather was cloudy to rainy, the wind was weak to the north," he said.
In CCTV footage monitored by the Lumajang BPBD, secondary eruptions were observed in the Besuk Kobokan and Kali Lanang river basins, so the public is advised to be alert to hot lava flows.
The highest mountain on the island of Java experienced an eruption on Sunday at 00.13 WIB with no visual eruption being observed, however the eruption was recorded on a seismograph with a maximum amplitude of 22 mm and a duration of 134 seconds.
Then the eruption of Mount Semeru occurred again at 19.10 WIB with no visual eruption being observed, the eruption was recorded on a seismograph with a maximum amplitude of 22 mm and a duration of 114 seconds.
The status of the mountain, which has a height of 3,676 meters above sea level, is still at alert status or level III, so that people are prohibited from carrying out any activities in the southeastern sector along Besuk Kobokan, as far as 13 km from the peak (center of the eruption).
Outside this distance, people are asked not to carry out activities within 500 meters of the river bank (river border) along Besuk Kobokan because they have the potential to be affected by the expansion of hot clouds and lava flows up to a distance of 17 km from the peak.
Then, people are not allowed to carry out activities within a 5 km radius of the crater/top of Mount Semeru because they are prone to the danger of throwing stones (flare).
The public is also advised to be aware of the potential for hot clouds, lava avalanches and lahars along rivers/valleys that originate at the peak of Mount Semeru, especially along Besuk Kobokan, Besuk Bang, Besuk Kembar and Besuk Sat as well as the potential for lahars in small rivers which are tributary of Besuk Kobokan.