The frequency of the volcano's multiphase quakes was higher on Friday, with magma moving upward to a distance of 1.5 kilometers away from the surface, said BPPTKG chief, Hanik Humaida.
The magma has come close to the surface, but it has not emerged from the volcano's peak, he added.
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The areas at the highest risk will be in the northwest, and west to southeast of the volcano, which straddles the provinces of Central Java and Yogyakarta, he informed.
Hence, residents living in areas stretching from the northwest to southeast of the volcano must remain on high alert, he said. However, those living north and northeast of the volcano should also remain vigilant, he added.
Mount Merapi has frequently erupted over the past decade. In 2010, ANTARA had reported an eruption that had claimed about 300 lives.
On June 21, 2020, the 2,930-meter-high volcano, situated on the border of Yogyakarta's Sleman district and Central Java province, had erupted twice, spewing a six thousand-meter-high column of ash.
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