Krakatoa

Eskander

Overview

• On August 27th, 1883 a series of blasts on the island of Krakatoa culminated in a colossal explosion that blew the island apart in one of the largest eruptions in recorded history. Below are a few brief facts about the blast and its effects.

How the eruption took place

• 1. The 23km square island of Krakatoa existed at a height of 450m above sea level. The blast leveled most of the island to 250m below sea level.

2. Pyroclastic flows traveled as far as 40km from the island consuming traversing ships in fire and ash.

• 3. The sound of the final explosion was heard over 4500km away and covered 1/13th of the Earth's surface.

• 4. The eruption generated tsunamis 40m high that devastated nearby coastlines.

• 5. The final death toll from pyroclastic flows, volcanic explosions, and tsunamis was calculated to be a devastating 36,417.

Questions?

• What was the death toll for krakatoa?

• The death toll for Krakatoa was a estemated 36,417

• In what ways did the eruption affect the weather globally?

• The eruption affected the climate because there was so much ash shot up into the atmosphere.

• How would you classify the type of destruction that took place?

• Based on what you know, how would you explain the sires of eruptions and the stages of devastation?

• What made this eruption so deadly?

Fun Facts• Tephra from the eruption fell as far as 2,500

km downwind in the days following the eruption. However, the finest fragments were propelled high into the stratosphere, spreading outward as a broad cloud across the entire equatorial belt in only two weeks. These particles would remain suspended in the atmosphere for years, propogating farther to the north and south before finally dissipating.

• The stratospheric cloud of dust also contained large volumes of sulfur dioxide gas emitted from Krakatau. These gas molecules rapidly combined with water vapor to generate sulfuric acid droplets in the high atmosphere. The resulting veil of acidic areosols and volcanic dust provided an atmospheric shield capable of reflected enough sunlight to cause global temperatures to drop by several degrees.

• This aerosol-rich veil also generated spectacular optical effects over 70% of the earth's surface. For several years after the 1883 eruption, the earth experienced exotic colors in the sky, halos around the sun and moon, and a spectacular array of anomalous sunsets and sunrises. Artists were fascinated by these aerial displays and captured them on canvas. The painting shown here is one such sunset captured by the artitst William Ascroft on the banks of the River Thames in London, on November 26, 1883 (Courtesy of Peter Francis).

Bibliography

• How Volcanoes work, KRAKATAU, INDONESIA (1883)

• http://www.geology.sdsu.edu/how_volcanoes_work/Krakatau.html

• http://www.earlham.edu/~bubbmi/krakatoa.htm Author: Michael BubbCreation/revision date: April 18, 2004