Anak Krakatau Erupts 42 Times from Midnight to Midday

Mount Anak Krakatau (GAK) in the Sunda Strait was recorded as having erupted 42 times on Tuesday (25/8) — from midnight until midday.

This was stated in a report uploaded to the Magma Indonesia page, owned by the Ministry of Energy and Mineral Resources, based on monitoring during the period from 00.00 to 12.00 WIB.

The report states that from 00.00 WIB to 06.00 WIB, Mount Anak Krakatau erupted eight times, with amplitudes of 55–66 mm and earthquake durations of 71–971 seconds.

This was followed by 60 emission earthquakes with amplitudes of 12–59 mm and durations of 10–105 seconds. There were also six harmonic tremors with amplitudes of 45–62 mm and durations of 43–757 seconds.

Anak Krakatau also experienced three low-frequency earthquakes with amplitudes of 19–42 mm and durations of 13–20 seconds.

There were 16 hybrid or multi-phase earthquakes with amplitudes of 21–58 mm, S-P not observed, and durations of 16–27 seconds.

One continuous tremor earthquake was recorded with an amplitude of 2–50 mm, dominant at 10 mm.

“Grey and black smoke was observed from the main crater with thick, high intensity, reaching approximately 50–300 metres above the summit,” the report stated, as quoted on Tuesday evening at 15.31 WIB.

From 06.00 to 12.00 WIB, GAK was recorded as experiencing 34 eruption earthquakes with amplitudes of 44–69 mm and durations of 25–290 seconds.

In the monitoring report accessed on the Magma Indonesia website, the 34 eruptions of GAK took place from 06.00 to 12.00 WIB.

“132 emission earthquakes with amplitudes of 13–66 mm and durations of 7–21 seconds,” wrote monitoring officer Rioboniek Situmorang in his report on the Magma page.

The active volcano, located in the waters of the Sunda Strait at an elevation of 157 metres above sea level, spewed volcanic ash with thick intensity reaching heights of 100 to 400 metres.

GAK, which erupted violently in 2018 and subsequently caused a tsunami along the southern Sunda coast, also experienced four harmonic earthquakes with amplitudes of 37–61 mm and durations of 17–83 seconds during the monitoring period from 06.00 to 12.00 WIB.

“One low-frequency earthquake with an amplitude of 44 mm and a duration of 12 seconds,” he added.

There were also 23 hybrid or multi-phase earthquakes with amplitudes of 17–53 mm and durations of 7–21 seconds.

One continuous tremor earthquake was recorded with an amplitude of 3–60 mm, dominant at 20 mm.

“The public and tourists are prohibited from approaching Mount Anak Krakatau or carrying out activities within a 3 km radius of the active crater,” he said.