JAKARTA - The Geological Agency of the Ministry of Energy and Mineral Resources (ESDM) reported that the eruption and non-harmonic tremor dominated the volcanic activity of Mount Marapi in West Sumatra (Sumbar).
"The earthquake data of Mount Marapi is dominated by thrust earthquakes and non-harmonic tremors during the period of 1-15 April 2026," said Acting Head of the Geological Agency Lana Saria through a written statement received in Padang, Tuesday, quoted by Antara.
This was conveyed by Lana regarding the evaluation of the activities of Mount Marapi which is located in Agam Regency and Tanah Datar Regency for the period 1 to 15 April 2026.
During the last two weeks, the Geological Agency recorded five times of eruption or eruption earthquakes. Then 61 times of eruption earthquakes, 103 times of non-harmonic tremors, eight times of low frequency earthquakes, eight times of shallow volcanic earthquakes, 17 times of deep volcanic earthquakes, 17 times of local tectonic earthquakes, one time of earthquake felt with a scale of III MMI, and 42 times of distant tectonic earthquakes.
During the observation period, he continued, visually Mount Marapi was clearly visible until it was covered with fog. The main crater smoke was observed to be white and gray with a thin to medium intensity with a height of 50-600 meters from the volcano's peak.
Then visually Mount Marapi showed an eruption and the eruption was still going on with a relatively stable intensity without significant increase compared to the previous period.
According to him, the volcanic activity is relatively stable, there is no increase in earthquakes indicating the addition of magma supply from depth.
Shallow fluid-pressure related earthquakes are observed in a limited number without significant tremor increase. In general, this condition indicates that there is no sign of increased activity leading to an increase in the level of activity of the mountain.
Furthermore, he explained that the value of the Real Time Seismic Amplitude Measurement (RSAM) fluctuated around the baseline so as not to show any significant energy accumulation in Mount Marapi.
Furthermore, the value of seismic velocity variation (dv/v) is dominated by negative values with fluctuations in the low to medium range that physically reflect the decrease in elastic modulus (stiffness) of the medium in the shallow part.
However, he continued, the negative value does not show a pattern of continuous and sustainable decline but fluctuates around a relatively similar range without deepening anomalies. Meanwhile, the coherence value is at a medium to high level and relatively stable.
"Based on the evaluation of monitoring data in the last two weeks, the activity of Mount Marapi in general still shows a fluctuating pattern," said Lana Saria.
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