Explosive activity at Anak Krakatau in Indonesia continues and its seismicity is reportedly going off the scale today, July 12, 2018.

"Krakatau is going crazy ... 100 times explosion a day. Very loud and could be heard until Carita, 42 km (26 miles) away," Volcano Discovery's Indonesian volcano expedition leader said July 12.

Image credit: Magma Indonesia

Just a few hours ago, photographer and volcano-enthusiast Øystein L. Andersen, said activity at the volcano is quite unique now. "It seems like you can now see a bright glow from the eruption from the coast of Java, 50 km (31 miles) away."

PVMBG reported there were four ash-producing events at Anak Krakatau on July 4 and 5, each lasting between 30 and 41 seconds. While inclement weather conditions prevented an estimation of the ash-plume height from the event at 05:22 local time on July 4, ash plumes from events at 14:09, 14:25, and 16:51 on July 5 rose 300 - 500 m above the crater rim and drifted N and NW.

At this time, the Alert Level remains at 2 (on a scale of 1-4). Residents and visitors were warned not to approach the volcano within 1 km (0.62 miles) of the crater.

Geological summary

The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. The collapse of the ancestral Krakatau edifice, perhaps in 416 CE, formed a 7-km-wide (4.3 miles) caldera.

Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano.

This eruption, the 2nd largest in Indonesia during historical time, caused more than 36 000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km (25 miles) across the Sunda Strait and reached the Sumatra coast.

After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927. (GVP)

Featured image: Anak Krakatau eruption on July 6/7, 2018. Credit Sam. Hidayat via Øystein L. Andersen