Strong eruption at Merapi volcano — ash to 7.8 km (25 500 feet) a.s.l., Aviation Color Code raised to Red, Indonesia

A moderately strong eruption took place at Indonesia's most active volcano — Mount Merapi, on Friday, March 27, 2020, ejecting ash up to 7.8 km (25 500 feet) above sea level and forcing authorities to raise the Aviation Color Code from Green to Red. This is Merapi's second major eruption this month.

The eruption started at 03:56 UTC (10:56 LT) and lasted for 420 seconds with a max amplitude of 75 mm. The Aviation Color Code was raised from Green to Red at 04:15 UTC.

Pyroclastic flows traveled 2 km (1.2 miles) to the south-southeastern sector following the eruption.

Ashfall was reported in places up to 20 km (12.4 miles) away from the volcano, especially in the Western sector where it reached the Mungkid sub-district of the Magelang regency. Ashfall was also reported in the village of Banyubiru in the Dukun district, about 15 km (9.3 miles) from the volcano.

Image credit: BPPTKG

Volcanic ash is clearly discernable on the latest satellite imagery, the Darwin VAAC reported at 06:25 UTC. High-level volcanic ash to 7.6 km (25 000 feet) a.s.l. and 3.3 km (11 000 feet) a.s.l. has disconnected from the summit. Low-level volcanic ash observed to 3 km (10 000 feet) a.s.l. is moving west.

National disaster mitigation agency spokesman Agus Wibowo said there have been no reports of damage. "We urge people to stay calm and not panic," he added.

Residents are advised to stay away from the summit within a 3 km (1.9 miles) radius.

The eruption came without a clear precursor– a day prior, only three volcanic earthquakes were recorded, volcanologist Tom Pfeiffer of the Volcano Discovery reports. "This type of eruption can thus, occur with little to no warning."

It is also 'an indication that the (currently slow) supply of magma into the volcanic edifice is still ongoing.' The last estimated volume of the lava dome was 291 000 m³ (10.3 million ft³) on February 19.

On March 2, a high-level eruption took place at the volcano, shooting ash up to 10.7 km (35 000 feet) above sea level. The Adi Soemarmo International Airport in Surakarta temporarily closed following the explosion.

Mount Merapi's last major eruption was in 2010, resulting in more than 300 fatalities and the displacement of 280 000 residents.

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 the 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.

Subsequently, the growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive 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 during historical time. (GVP)

Featured image credit: BPPTKG