Read and Grade Henry's Volcano Report

Mrs. Ridley's science class is studdying volcanos. You could make a model of a volcano or write a report. Henry wrote a report. In the comment area following or by email ( give Henry a grade. Please include an explanation of why that grade. If you are student please share what grade you are in.

Student: Henry Miller
Teacher: Ms. Ridley

Krakatoa: A Blast in the Past

Krakatoa is a volcanic island in the Indonesian chain of islands by the same name. The islands are located between Java and Sumatra. The name is used for the island group, the main island (also called Rakata), and the volcano as a whole. On maps and in Indonesian it is spelled Krakatua. I will use the name to speak of the volcano. Krakatoa is probably one of the most famous volcanos in the world, possibly only Mount Vesuvius is better known. (When asked, my parents could name both of them, Friends at school had not heard of either of them.)

The islands are in the straits of Sundra and were frequently passed by British and Dutch ships during the colonial period. Krakatoa was at times through history inhabited but in the 1883 there were no residents. Beginning on August 26, 1883 and continuing on the 27th the volcano erupted in four blasts that blew away two thirds of the island. The eruption was estimated to be 13,000 times greater than the atomic bombs used in World War Two. The sound was so great that it was reported to be heard in Perth, Australia, 1,930 miles away and in the island of Rodrigues, 3000 miles away. It is estimated that it caused deafness to anyone within ten miles of the blast.

Though no one lived on the island of Krakatoa it is estimated that the number of people killed range from an official estimate of 36,000 to as high as 120,000. Most people were killed in three different ways. The initial eruption sends out a pyroclastic flow. This is a wave of super-hot gas and rock that moves out from the volcano at speeds as fast as 700 miles an hour. This wave travels very close to the surface of the land or water. 

The volcanic ash can also kill people. The ash plume from Krakatoa was estimated at 50 miles high.  Most people though were killed by the tsunami. Like an earthquake, an eruption of this size has the ability to create a tsunami that would spread far beyond the region. Because the island was made by the volcano much of the island was pumice. Pumice is a stone but it is so lite it floats. There were documented reports of large chunks of pumice found floating in the Indian Ocean with human skeletons on them. There were also less documented claims that floating islands with wild animals on them were seen.

The area remains active. In 1927 a new island emerged a little north of the previous volcanic center. This new active volcano is known as Anak Krakatoa or child of Krakatoa. Lava flows continue to build the island and expand its size. And the possibility of life threatening eruptions remains.

Our modern technology has given us many ways to monitor volcanos but we still have no accurate means of predicting an eruption and little ability to control the effects. A few years ago an Icelandic volcano caused the airports of Europe to close for a week. Volcanic eruptions regularly cause airplanes to alter their routes.

In modern times only one other volcano was more deadly than Krakatoa. That eruption was also in Indonesia and occurred in 1815.  Quite possibly, that eruption is not as well-known because it occurred before the invention of the telegraph. Until international telegraph communication was established news between America and Europe took as much as a week. News from other parts of the world took weeks or months. Telegraph communication between Australia and Europe was established in 1872 just 11 years before the eruption of Krakatoa.  The news of the Krakatoa eruption traveled around the world in less than 24 hours making it possibly the first natural disaster news to do so.


 Hopkinson, Deborah (Jan 2004). The Volcano That Shook the world: Krakatoa 1883.

Wikipedia articles:


Pyroclastic Flow

List of Natural Disasters By Death Toll