Lava flows at Merapi volcano as it enters new effusive eruption phase, Indonesia

Mount Merapi has entered a new effusive eruption phase on January 29, 2019. The Alert Level remains at 2 (on a scale of 1-4), and residents are warned to remain outside of the 3-km (1.8 miles) exclusion zone.

Lava flow produced by the eruption reached a distance of 1.4 km (4 590 feet) down its slopes on January 29, head of the Volcanology and Geological Hazard Mitigation Center said. He added that the volcanic material that spewed out late Tuesday was the volcano’s longest lava flow since it began erupting again in August.

The activity at the volcano on January 26 and 27 was characterized by 9 rockfalls, 3 explosions and 1 low frequency and 2 tectonic quakes. Lava avalanches were visually observed and recorded on both days.

Increased activity at the volcano was reported two weeks ago, when lava flow reached a distance of up to 800 m (2 624 feet) down the slope of the volcano. Authorities said they were preparing evacuation routes and emergency shelters as well as calculating logistical needs in anticipation of a major eruption. 

Apart from incandescent lava, the volcano was emitting booming sounds resembling thunder more frequently, prompting local residents to also increase the frequency of their independently organized patrols.

PVMBG advised people to stay away from the upper slopes of the mountain for their own safety, especially considering the lava flow.

Thousands of people are living on the flanks of Mount Merapi, active stratovolcano regularly erupting since 1948. It is located about 28 km (17 miles) north of Yogyakarta city (population 2.4 million).

At least 353 people were killed and more than 350 000 other displaced after the volcano erupted in 2010 (VEI 4).

In November 1994, a large explosion at the volcano produced pyroclastic flows that killed 27 people. 

Official Merapi webcams

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. 

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.

Featured image credit: BPPTKG