In our everyday, technology filled lives; it is easy to forget that the earth is dynamic. Our planet is constantly changing, whether we realize it or not. The landforms that we take for granted are in many cases the result of earth’s violent and relentless activity that has persisted for billions of years. This third planet from the sun is our home, but Earth does not care about us. Nature is not required to make sense nor consider human existence regarding its activity. What seems static from a human perspective is in a constant state of movement. Natural disasters often remind us that Mother Nature is more powerful than humans and she must be respected.
Tectonic activity, such as volcanic eruptions are illustrations of Earth’s volatility. Though there have been more recent blasts in modern times, none have been more deadly than the eruption of Krakatoa on August 26, 1883. Krakatoa (or Krakatau) is a small island located between Java and Sumatra in the Indonesian Island Arc. The island is only about 3 miles wide and 5 miles long. These islands and the volcanic activity in the region is the result of tectonic movement below the sea floor. The Indo-Australian plate is subducted under the Eurasian and Pacific plates as it moves slowly northward toward the Asian mainland. When Krakatoa erupted in August of 1883, an estimated 36,000 people were killed. Many perished due to the eruption, but many more died after the resulting tsunami following the collapse of the volcano into the caldera below.
With our advanced modern technology, we are able to detect natural hazards like severe weather and also monitor earth’s internal movement. For example, in 1980, geologists were able to detect seismic activity and knew that Mount St. Helens would erupt soon, saving the lives of many. The brave Krakatoans (10 points if you caught the Seinfeld reference there) had no warning system or advanced notice. Before nature was understood at the level it is today, it was more respected and spawned many legends and folktales of angry gods and evil spirits. Those closest to the volcano in western Java and Sumatra were victims of the volcanic debris and hot gases from the blast. Countless thousands more were killed by the 120 foot high wall of water from the following tsunamis. After the initial eruption on August 26, a cloud of gas and debris was sent some 15 miles into the atmosphere and it is believed that debris from this eruption clogged the neck of the volcanic cone, allowing pressure to build inside the magma chamber. The next morning, four massive explosions were heard as far away as Perth, Australia (about 2800 miles) and much of the island collapsed into the caldera. According to the Volcanic Explosion Index (VEI), the eruption of Krakatoa is given a rating of 6, which is comparative to the explosive force of 200 megatons of Trinitrotoluene (TNT). The eruption of Mount St. Helens in 1980 had a VEI rating of 5.
Just a few months prior to the eruption in May of 1883, the captain of a German warship reported a cloud of ash over Krakatoa that he estimated to be over 6 miles high. Other vessels in the area reported seeing similar sites and heard explosions. Inhabitants of the neighboring islands celebrated and held festivals in honor of the display of lights in the night sky. The celebrations would end tragically with the eruption and ensuing tsunami on August 27.
The first explosion ruptured the magma chamber, sea water rushed in causing the water to flash-boil. The force of this phenomenon created a steam-generated explosion that propelled pyroclastic materials over 25 miles at speeds of over 60 mph. The eruption sent about 11 cubic miles of volcanic debris in the lower atmosphere that darkened the skies for nearly 300 miles from the volcano. The effects of the eruption of Krakatoa were not only felt in the immediate area of the volcano. Because of the debris in the atmosphere, Europe and the United States experienced unusually brilliant sunsets and for the next five years, the average global temperatures would be about 1.2 F degrees cooler.
Krakatoa was not the largest eruption in the modern era, but it was certainly responsible for the largest loss of life. Could an eruption of this magnitude happen again? Absolutely. Do we know where or when? Nope. But be assured that the U.S. Geological Survey has its eye on many locations. Nevertheless, there is nothing that we can do about an eruption other than be prepared.
So stop worrying and enjoy this beautiful day. Earth always wins in the end.
- McKnight’s Physical Geography: A Landscape Appreciation, Tenth Edition, Hess