An officer at the Semeru Volcano Observation Post, Ghufron Alwi, said that the cold lava tremor occurred on December 25 from 12 p.m. to 6 p.m. local time, based on the observation of the mountain's seismic activities.
"We observed a flood tremor earthquake with an amplitude of 15 mm that lasted for 5,400 seconds (1.5 hours)," he noted in his written statement in Lumajang on Monday.
Based on the observation, Alwi said the area also experienced 15 eruption jolts, with the amplitude in the range of 11-22 mm that lasted for 68-145 seconds as well as an avalanche tremor, with an amplitude of 66 mm, and lasted for 68 seconds.
The seismic activities of the highest mountain on Java Island also involved two gust tremors and two distant tectonic tremors, he pointed out.
"The volcano is still visible despite being covered by fog at times, while smoke from its crater is not apparent. The weather ranges from sunny to rainy, with weak-to-moderate winds blowing to the north and northeast," he said.
Meanwhile, Head of Prevention, Preparedness, and Logistics at the Lumajang Disaster Mitigation Agency (BPBD) Wawan Hadi Siswoyo emphasized that the agency, along with volunteers, had continued to appeal to local people and sand miners to remain vigilant toward Mount Semeru's cold lava.
"We keep disseminating information and urging people to remain alert, especially in the event of rain pouring down the peak of Semeru. We have also been appealing to miners to stay away from river basins stretching along Semeru," he pointed out.
He said that the volcano is still under a standby level, meaning people should not conduct any activities in the south eastern sector of the mountain area, or within 13 kilometers from the peak.
Siswoyo also urged people to not venture within 500 meters of the river bank, as there is a possibility of the area being affected by hot clouds and lava flows.
"Furthermore, people are not allowed to carry out activities within a 5-km radius of the peak of Mount Semeru because the zone is prone to incandescent stones," he said.
He called on local residents to be vigilant toward the threats of hot clouds, lava, and volcanic mudflow along rivers and valleys in the regions of Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat.
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Translator: Tegar Nurfitra Putra Rofian
Editor: Tia Mutiasari
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