Krakatoa eruption

Lore & Background

Earthquakes had shaken the region for years beforehand, including one in 1880 that damaged a lighthouse. On 20 May 1883 steam and ash began venting from Perboewatan, the northernmost of the island's three cones, with explosions rattling windows in Batavia (Jakarta) 160 km away.

Activity waxed and waned through June and July as new vents opened between Perboewatan and Danan, and the Dutch engineer Captain H. J. G. Ferzenaar found vegetation stripped bare in early August. The climactic phase began at about 1:00 p.m. on 26 August, with an ash cloud 27 km high by mid-afternoon. On 27 August eleven enormous explosions followed, and at 10:41 a.m. a landslide tore away half of Rakata's cone.

Reader's Guide

The third explosion was heard 3110 km away in Perth, Western Australia, and on Rodrigues near Mauritius, 4800 km distant, where people mistook it for cannon fire. Its pressure wave was recorded seven times over five days on barographs worldwide, circling the planet more than three times, and it burst the eardrums of sailors on RMS Norham Castle about 64 km away.

The energy released is put at about 200 MtTNT. Tsunamis did the most killing: one 46 m wave destroyed the town of Merak, and waves reached up to 42 m on the west coast of Java. Later reports of activity were set aside by Rogier Verbeek's investigation.

Did You Know?

• Near the volcano itself the largest blasts were barely heard, possibly because sound was deflected up into the stratosphere.
• The low-lying Thousand Islands, some 80 km away, were covered by 2 m of seawater.
• Volcanic material was hurled out at 2575 km/h.
• Distant islands probably heard the blast nearly four hours after it happened.