JAKARTA, Sept 6 — Indonesia’s Anak Krakatoa volcano remains highly active and could intensify despite a significant decline in the strength of volcanic seismic signals recorded today.

Volcanology and Geological Hazard Mitigation Centre (PVMBG) Head Siti Sumilah Rita Susilawati said the volcano’s seismic amplitude had declined significantly, but its dynamics remained very high, with the Geological Agency continuing round-the-clock monitoring.

“The dynamics remain very high, so this decline does not necessarily indicate that the activity has stopped. There is still a possibility that the activity could increase,” she told an online press conference today.

The National Disaster Management Agency (BNPB), in an update today, said the continuous eruption began at about 11.07pm on September 4, accompanied by rumbling and banging sounds as well as lava fountains, while the Geological Agency, in a September 5 special report, said the latest activity was part of a series of eruptions that began on July 2.

On the latest ash distribution as of 10.30am, Siti Sumilah said a dense ash cloud at about 50,000 feet, or 15 kilometres above sea level, had moved away from the active crater and was drifting southwest towards the Indian Ocean.

“At around 20,000 feet, or six kilometres, volcanic ash emissions continuing from the crater vent are being carried westward by the wind, while residual fine ash from the previous eruption phase is shifting eastward towards waters south of the Sunda Strait,” she said.

Meanwhile, Geological Agency Head Lana Saria said Anak Krakatoa remained at Level III (Alert), the second-highest level in Indonesia’s four-tier volcano alert system, with the threats identified in the agency’s overall assessment remained concentrated around the volcano and within the recommended three-kilometre radius.

She said no potential threat to residential areas identified at present.

“The recommended radius may be expanded if there is a significant increase in the energy or scale of the eruptions, volcanic material reaches greater distances, deformation or pressure within the volcano increases, or pyroclastic flows or other hazards emerge beyond the three-kilometre radius,” she said.

According to a 2006 paper by a PVMBG volcanologist published in the Indonesian Journal on Geoscience, Anak Krakatoa emerged above sea level in 1929 within the caldera formed by the catastrophic 1883 Krakatoa eruption, which generated tsunamis that killed more than 36,000 people.

Anak Krakatoa was itself associated with a deadly tsunami nearly 90 years later, with BNPB saying in a 2018 disaster report that an underwater landslide linked to its eruption triggered a tsunami in the Sunda Strait on December 22 that year, killing 437 people. — Bernama