Krakatoa may just be the most famous volcano of all time. More devastating than Mt. St. Helens, closer in time than Vesuvius; the volcano that destroyed itself and its island in one tremendous eruption is nearly iconic in the public eye.
The famous eruption of Krakatoa on August 27, 1883 has been estimated as the biggest bang in recorded history, heard over 3000 miles away. It killed over 36,000 people, and destroyed more than 3/4 of its island, literally blowing it to pieces. The cataclysm affected weather world-wide, cooling summers, and causing sunsets so vivid that in Poughkeepsie, NY, firefighters were called to put out the apparent conflagration.
All of this is well-known. What is less well known is that this same volcano is a repeat offender, and it is still with us. The sea bed just to the north of what remains of Rakata island began rising steadily shortly after the famous cataclysm. In 1927, a new island called Anak Krakatoa (Son of Krakatoa) emerged from the sea to take its father's place.
Krakatoa itself is the reformation of an earlier volcano.
The original volcano also exploded, creating the strait between Java and Sumatra. The event is recorded in the Javanese Book of Kings.
"A thundering sound was heard from the mountain Batuwara ... a similar noise from Kapi ... The whole world was greatly shaken and violent thundering, accompanied by heavy rain and storms took place, but not only did not this heavy rain extinguish the eruption of the fire of the mountain Kapi, but augmented the fire; the noise was fearful, at last the mountain Kapi with a tremendous roar burst into pieces and sank into the deepest of the earth. The water of the sea rose and inundated the land, the country to the east of the mountain Batuwara, to the mountain Raja Basa, was inundated by the sea; the inhabitants of the northern part of the Sunda country to the mountain Raja Basa were drowned and swept away with all property... The water subsided but the land on which Kapi stood became sea, and Java and Sumatra were divided into two parts."
The book claims a date of 416 AD for the eruption, though the geologic evidence seems to indicate an eruption of 535 AD. The eruption drowned the land between Java and Sumatra in the ocean, leaving behind only a small ring of tiny islands. The largest of these eventually grew into Krakatoa, an island with three volcanic peaks, and an explosive future.
When Krakatoa exploded, it destroyed two of those three peaks, leaving only the southernmost - Rakata - still above sea level. The original site of the explosion was buried under a thick layer of fallen debris. However, Krakatoa was not to remain hidden for long. In 1927, Javanese fisherman reported seeing steam and debris rising from the collapsed caldera. Anak Krakatoa rose above water for the first time on January 26, 1928. For three years the new island fought a war with the sea, slipping back beneath the waves repeatedly as the waves washed away the pumice and ash that formed it. In 1930, the son of Krakatoa won its battle, and surfaced above the waves for good.
Today Anak Krakatoa is 2 km in diameter, and rises more than 150 meters out of the ocean. It has grown an average of 13 cm (5 inches) per week in the last sixty years. It's an active - very active - volcano with multiple episodes of volcanic activity since 1963, the most recent having started in 1994. Since then Anak Krakatoa quiet periods have been measured in days, punctuated with explosions and eruptions. Reports from 2005 indicate that volcanic activity at Anak Krakatoa is increasing. Thus far the eruptions of Anak Krakatoa have been mild, especially as compared to the father. Nonetheless, given its illustrious ancestry, the awe with which many view it seems amply justified.