Activity from Anak Krakatau's 100-m-diameter 1978 crater resumed in mid-July. Bombs (average diameter 1 m), lapilli, and ash were ejected every 5-15 minutes, rising 200 m and covering the area within about 700 m of the crater. Lava flowed W, reaching the coast about 450 m away. A danger zone has been delineated within 3 km of the crater.

The 1979 eruption is stronger than that of 1978, when ash and lapilli were ejected, but no bombs or lava flows.

Geological Summary. The renowned Krakatau (frequently mis-named as Krakatoa) volcano lies in the Sunda Strait between Java and Sumatra. Collapse of an older edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of that volcano are preserved in Verlaten and Lang Islands; subsequently the Rakata, Danan, and Perbuwatan cones were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption caused more than 36,000 fatalities, most as a result of tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km 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 Danan and Perbuwatan cones. Anak Krakatau has been the site of frequent eruptions since 1927.

Information Contacts: A. Sudradjat, VSI.