Merapi volcano, Central Java 17-18th April 2021

Published: 19th April 2021


Activity of the Volcano:

Observed Merapi from a distance of 5 to 6.5 km to the South/Southwest of the volcano, for several hours on the 17-18th April. Weather conditions: 17th April clear conditions, 18th April fog but short periods were observation was possible.

The frequency of rockfall events from the 2021 lava dome was lower than during my visit in March 2021. On the 17th April, 74 rockfall events were recorded by Indonesian Authorities (BPPTKG). On the 18th April the number increased to 173 rockfall events and 1 pyroclastic flow. Because of the relatively poor weather conditions, I only were able to observe a few rockfall events visually. A particular rockfall event just before midnight on the 18th April produced the heaviest impact sounds that I heard from rockfall events from this lava dome (photo 14). In addition to observing the new 2021 lava dome on the SW flank of Merapi, I were able to spot the new lava dome that has emerged behind the 2018 lava dome within the summit crater of Merapi (see photo 13). My camera picked up some Incandescence on this lava dome, however it was not visible to the naked eye.

The 2021 lava dome on the SW flank has a volume of 1.034.800 m3 (as of 16th April 2021) according to BPPTKG.

5 km restriction zone is currently in place for Merapi volcano, according to Indonesian Authorities BPPTKG, The Center for Volcanology and Geological Hazard Mitigation, Geological Agency. The volcano is as of today 18th April still on alert level III.


Total photos in this article: 15 (Available in Jpg/Raw.) 

Total videos: not published online

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17-18th April 2021

Photo 1. Rockfall from the 2021 Lava dome.
Photo 2. Lenticukar cloud above the summit.
Photo 3.
Photo 4.
Photo 5.
Photo 6.
Photo 7.
Photo 8. Lawu volcano in the distance.
Photo 8. Aerial 180 degrees image of Merapi. 6 other stratovolcanoes are visible in this image as well: Sumbing, Prau (Dieng) Sindoro, Andong?, Merbabu and Lawu.
Photo 10.
Photo 11.
Photo 12. Merapi from the South, looking towards the 2018 lava dome. Incandescent rockfall on the SW flank can also be seen in this photo.
Photo 13. Glow from the lava dome.
Photo 14. Incandescent rockfall. Must have been some heavy rocks involved in this one, since the sound of the falling rocks could be heard very well.
Photo 15.