After almost one month since the local volcano institute decreased the alert status for the volcano, activity started to rise again over the past two weeks.
Since 15 May, glowing lava blocks have been observed detaching from the Main Crater’s lava dome that reached a 1.5 km sliding distance over the south and southwestern slope. The activity has been accompanied by ongoing release of gas and steam emissions (so-called degassing) to an estimated 2500 meters altitude, dissipating into various directions.
Visible glow and near-constant emissions of gas and steam at the North Crater’s lava dome suggest continuing fresh magma injection into the dome, as well.
The increasing trend of the activity is also shown in a continuous rise of seismic activity detected by the volcano observatory. During 1-17 May, the seismic station detected about 170 volcano-tectonic earthquakes. Magma continues to squeeze through surrounding rocks under the surface, which generates the elevated seismic energy. Afterwards, more and more unstable hot lava material in domes is accumulating and prone to collapse into hot rock falls, which in turn often develop into very dangerous pyroclastic flows as we know from previous activities.
To conclude, this led volcanologists to make a decision to rise the alert status from Level II (Waspada) to Level III (Alert).
In order to risk mitigation, people are not allowed to approach the Main crater area (south) within a 2.5 km radius and the North crater area within a 3.5 km radius. Due to the accumulation of relatively fresh lava material, resulting from lava flows and dome blocks, the current hazards for people may pose hot avalanches that are prone to collapse and can become mobilized into pyroclastic flows of various sizes.
In early February, the volcano entered into the intense phase by generating incandescent avalanches from the fresh magma-filling lava dome within Crater 1 onto the western and eastern slopes. The situation intensified by dangerous pyroclastic flows on the southeastern side in late February.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi volcano activity update 19 May 2023