BPPTKG reported that parts of Merapi’s summit lava dome collapsed during 9-10 March, sending pyroclastic flows as far as 5 km SE down the Gendol drainage. At around 2318 on 9 March ash plumes rose at least 3 km above the summit and drifted SE. Ashfall was reported in several villages downwind, including in the Kemalang, Sawangan, Dukun, and Selo sub-districts, and 50 people from Bale Rante Village evacuated. The total volume that collapsed was an estimated 646,000 cubic meters, making the volume of the remaining dome material about 2,582,000 cubic meters.

Overall, during 4-10 March, there was a total of 101 lava avalanches and one pyroclastic flow that descended the Bebeng drainage on the SW flank a maximum distance of 2 km. Extrusion at the SW lava dome continued; the volume of the dome was an estimated 1.58 million cubic meters, similar to the previous few weeks. Pyroclastic flows in the Gendol drainage totaled 18 during the week, and there were 17 lava avalanches that traveled as far as 1.5 km. Seismicity remained at high levels with an increase in the intensity of signals. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-5 km away from the summit based on location.

Geological Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

Sources: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG), Badan Nacional Penanggulangan Bencana (BNPB)