Knowledge Article: World Geography Ring of Fire Plate Tectonics Certain regions of the world are more vulnerable to natural disasters because of where they are located. Tectonic plates beneath the surface of the earth are constantly grinding against each other. This action produces a great amount of energy, which is sometimes released through geologic episodes, including earthquakes and volcanic eruptions. One region of the planet experiences this activity more than any other the "Ring of Fire." The Ring of Fire The Ring of Fire runs along the edges of the Pacific Ocean, including Southeast Asia. There, the main Pacific Plate and several smaller ones collide with each other. This ongoing collision creates massive mountain chains, volcanic islands, frequent earthquakes, and highly destructive tsunamis. It should also be noted that the Ring of Fire contains some of the largest population centers in the world, including Japan, Indonesia, and the western coast of the United States. As a result, when a natural disaster does occur along this zone, it can cause severe damage and claim many lives. The Pacific "Ring of Fire" stretches around the rim of the Pacific Ocean. 1 2013 EDMENTUM, INC.
The tectonic plates on Earth s surface drift over time. Hundreds of millions of years ago, the modern continents were all part of one supercontinent. Slowly, over the course of time, the continents moved to their current positions. As you might imagine, when huge forces such as these plates come together, there is a massive amount of energy produced. In these regions, much of that energy gets released as seismic (earthquake related) or volcanic activity. One of the most commonly seen plate boundaries is a subduction zone. At a subduction zone, an oceanic plate collides with a continental plate, and because the oceanic plate is denser, it slides (subducts) under the continental plate. This subduction results in the creation of continental volcanic mountain ranges and volcanic islands along the plate boundaries. This exact process has played itself out along many of the edges of the Pacific Ocean, creating the Ring of Fire. As the edges of the hard, rocky oceanic plates disappear under the continents, the heat of the Earth melts them back to a molten state. With nowhere to go, this magma forces its way up through the earth. Eventually it spews through volcanoes as lava. The Ring of Fire itself contains more than half of the worlds' volcanoes. Over millions of years, the subduction of tectonic plates has been an unending process in this area of the world. Like the conveyer belt in a grocery store checkout line, the sea floors have constantly been pushing under the continents. Fiery Indonesia The Ring of Fire has created a zone of geological chaos around the Pacific Rim. The ocean is surrounded on virtually every side by sizeable mountains and islands. From New Zealand through the islands of Southeast Asia, to Japan and Eastern Siberia, and along the coast of the Americas from Alaska to the Southern tip of South America, there are active and dormant volcanoes. These geological forms provide the fire in the name Ring of Fire. They are, however, by no means the only danger in the region. Earthquakes are especially prominent in Southeast Asia, Japan, and the Pacific Coast of the Americas. These movements deep within the earth are caused by sudden shifts when the continents, constantly grinding against each other, suddenly release pressure. The effects of the Ring of Fire on Southeast Asia can clearly be seen by looking at a physical map of the region. Thousands of islands dot this Major volcanic sites of Indonesia are indicated with red triangles. Marked in green are the approximate sites of Krakatoa and the point where the 2004 earthquake-tsunami began. 2
region from eastern New Guinea to the Indian Ocean. Many of these islands were first created by volcanic activity or other tectonic events. However, the same natural forces that have helped shape the region also threaten it. The islands of Southeast Asia lie on the boundaries of three massive tectonic plates the Australian, Pacific, and Eurasian plates. The Indian and Philippine plates are also large and actively moving. With all these forces pushing against each other, the region has become a center of seismic and volcanic activity. Often at sea level, and with few natural barriers against waves, many islands of Southeast Asia are easily damaged by tectonic activity. In some extreme cases, islands can literally be washed away or blown apart. The remainder of this article will examine two of the most destructive natural disasters in this area's recent history the 1883 Krakatoa eruption and the 2004 tsunami. The Deadly Volcanoes of Krakatoa The imposing sight of Krakatoa's south side was obvious to all that saw it. However, its lurking danger was unknown to many at the time. Indonesia is an archipelago in Southeast Asia that lies within the Ring of Fire. The country has a long history of fiery volcanic eruptions, which continue today. In fact, the archipelago currently has more than 100 active volcanoes. Indonesia was the setting for modern history's most powerful volcanic eruption, which took place on the island of Krakatoa in 1883. Although not much is left of this island, originally located between Java and Sumatra, its hollowed shell is a reminder of its important past. Krakatoa's volcanic eruptions had been documented for hundreds of years before the 1800s. By that time, the island had developed an unusual feature: it had three volcanoes that were connected together below the surface. So a single eruption could cause lava to flow out of two or more volcanoes at the same time. After a series of earthquakes struck in May 1883, Krakatoa's volcanoes started to rumble and churn out lava. These eruptions were not especially dangerous: they were small and confined to a small section of the uninhabited island. In fact, people traveled to Krakatoa to watch the volcanoes in action, and some even landed their sea vessels on the island to get a better look. Although it seemed like a magnificent sight, it did not compare to what was about to happen. 3
The mild volcanic activity continued through the summer, until an explosive eruption occurred on August 26. This outburst, which created an ash cloud that was 36 kilometers (22 miles) high, signaled the start of two days of volcanic activity that would slowly grow more powerful, intense, and deadly. Unfortunately, many people lived close enough to Krakatoa to experience this flare-up. They watched in terror as the volcanoes spewed out ash and molten lava. But the worst was yet to come. The next day, August 27, the most explosive eruptions of that summer destroyed Krakatoa. As the volcanoes' fiery energy spread ash and lava all over the region, the huge island collapsed into an underwater crater. Only a third of it remained above the ocean's surface. This volcanic activity was so loud that it was heard nearly 3,000 miles away! To put this distance in perspective, 3,000 miles is greater than the distance between Los Angeles and Washington, D.C. The eruptions of August 26 and 27 combined to form a catastrophe for Southeast Asia. Thousands of people died when pyroclastic flows and tsunamis swept through the region. The pyroclastic flows, or clouds of toxic gas and extremely hot volcanic material, floated out from the volcanoes first. They burned and killed many as they drifted away from Krakatoa. However dangerous they sound, the pyroclastic flows were not responsible for nearly as many deaths as the tsunami which followed. The Killer Waves Shockwaves from the eruptions sent powerful tsunami waves throughout Southeast Asia. The places nearest to Krakatoa were devastated by these waves. They were often submerged under many feet of water, leaving little untouched. On Sebesi, one of the islands closest to Krakatoa, the entire population drowned, and their bodies washed away. Not even the plants or trees on Sebesi were left behind by the sea waves. Other islands around Krakatoa were also hit by massive tsunamis. One eyewitness, who was five miles inland, described the terror of witnessing the water approach: All of a sudden there came a great noise. We...saw a great black thing, a long way off, coming towards us. It was very high and very strong, and we soon saw that it was water. Trees and houses were washed away The people began to...run for their lives. Not far off was some steep sloping ground. We all ran towards it and tried to climb up out of the way of the water. The wave was too quick for most of them, and many were drowned almost at my side one after another, they were washed down and carried far away by the rushing waters. You can see the marks on the hill side where the fight for life took place. Some dragged others down with them. They would not let go their hold, nor could those above them release themselves from this death-grip. --account of a Javanese field hand, from Krakatau, Indonesia,San Diego State University 4
The ocean was no safe place for people to be either. The powerful tsunamis threw ships off course, or even ejected them from the water altogether, carrying them onshore. The waves also battered many ships, leaving them damaged or destroyed. After ravaging Southeast Asia, the energy from the tsunami's waves radiated out and traveled across the world. In Sri Lanka, an island off the coast of India, it was powerful enough to kill one person. In more distant areas, the waves were not deadly, but still noticeable. For example, waves in South Africa were a few feet higher as a direct result of the tsunami. By the time it had reached Europe, the tsunami had become so weak that it was indistinguishable from normal waves. In the aftermath of Krakatoa, the Dutch (who controlled Indonesia) estimated that more than 36,000 people perished during the August eruptions and subsequent tsunamis. This estimate does not include the damage done to areas outside of Dutch control, which was substantial. The Effects of Krakatoa The explosive eruptions at Krakatoa rippled across the world and changed the sky, ocean, and air temperature. Some of these changes lasted for weeks, others for years. To those living during the 1883 eruptions, these effects were inspiring, strange, and frightening. Some of the most obvious results of the August 1883 eruptions were changes in the sky. Krakatoa's eruption launched several million tons of dust and ash into the atmosphere. For two years, this cloud made sunrises and sunsets look more vivid, and occasionally altered the apparent shape or color of the sun and moon. These changes in the sky inspired a number of works of art and literature, including a famous painting by Edward Munch called The Scream. The skies were not the only thing that changed after Krakatoa's eruption: the oceans and air temperature were also affected. The oceans filled with pumice, a volcanic rock that floats. Sometimes the pumice washed ashore in places as far away as South Africa. Air temperatures also changed after the August eruptions. The temperature dropped greatly in Southeast Asia, and there were slight dips in temperature across the rest of the world. 5 Krakatoa s physical changes over time, including the 1883 eruption and the beginnings of Anak Krakatoa s formation
However, the largest and longest lasting transformation happened on Krakatoa itself. As mentioned previously, the final day of eruptions destroyed most of the island. The underwater crater where the volcanoes once stood serves as a physical reminder of this event. Krakatoa may not look this way forever: a new volcano formed in place of the old ones during the early 20th century. It is named Anak Krakatoa, which translates to "Child of Krakatoa" in English. 2004: The Indian Ocean Tsunami The force of Krakatoa s eruption soon faded, along with memories of the event. However, Indonesia has remained a geologically active place. Although most geological events are mild, occasionally some are devastating. A recent example occurred in Southeast Asia occurred in the early 21st century. In the morning hours of December 26, 2004, the Eurasian and Indian plates began to rumble. Located off the coast of the Indonesian island of Sumatra, a 1,200-mile-long underwater fault suddenly moved. This event created one of the largest and longest lasting earthquakes ever recorded. In contrast to most earthquakes which last a few seconds, this one rumbled for 8 to 10 minutes. As a result, the seafloor moved violently, and a massive tsunami formed. The first waves were estimated to be as tall as 100 feet. Traveling quickly, they approached the shores of Indonesia and the Indian subcontinent in a matter of minutes. A crowd watches from a safe distance as waves come ashore in the Maldives islands during the 2004 tsunami. No Warning There was no warning system in place at the time for the people who lived in this area. Making matters worse, tsunamis are not noticeable to the average person until directly before they reach shore because the seafloor rapidly rises near landmasses. Simply put, as the water becomes shallower, the waves become taller. As the waves began crashing into nearby islands, buildings were quickly destroyed, and many people were washed out to sea, drowned, or crushed. The devastation was particularly bad in the poorer regions where the waves hit because many of the buildings in these areas were flimsy and poorly constructed. In addition, many people in those areas struck by the tsunami did not have the means to evacuate the disaster area. As a result, they had to wait among the destruction until help arrived. 6
While Indonesia s island of Sumatra was the worst hit area, within an hour Sri Lanka, Thailand, and India had all been hit by the tsunami. Of these, Thailand and Sri Lanka were particularly damaged. The death toll in these four countries was immense. Even thousands of miles away, waves 10 feet high reached the east coast of Africa. Although they were much smaller than the waves that had hit South and Southeast Asia, they still caused some casualties. Relief Pours In Just as was the case with Krakatoa over a century before, the actual geological event (in this case the earthquake) was not the primary source of destruction. Instead, the massive tsunami waves that resulted caused the most damage. The sheer number of people killed differed significantly between the Krakatoa eruptions and 2004 tsunami. Indonesians on Sumatra receive critical food aid from a U.S. Navy Helicopter. In all, around 200,000 people died as a result of the 2004 tsunami. These deaths were not limited to the native citizens of Southeast Asia and East Africa. Many of the countries directly hit by the tsunami were popular tourist destinations. As a result, people from all over the world vacationing in Southeast Asia were also caught in the destruction. Images of devastation from the disaster were flashed around the world and drew a massive response from many countries. Many Western governments came out immediately to pledge funding for the relief efforts. The fact that the disaster occurred one day after Christmas also inspired a great deal of sympathy. Several countries mobilized military forces to help deal with the crisis. Non-governmental organizations and aid workers rushed to the region, and donations from ordinary citizens around the world poured in. This massive response at least limited the number of people who suffered from the post-tsunami effects. All told, the official and private funds donated for the crisis came to more than $12 billion within a year of the event. The quick and massive responses from many countries undoubtedly helped save lives after the initial shock of the disaster. 7
Preparing for the Future Despite the fact that the tsunami had been detected by many monitoring stations in other parts of the world, a warning did not arrive in South or Southeast Asia in time to save lives. The Pacific Tsunami Warning Center (PTWC) already existed in the Pacific Ocean to guard against the possibility of just such a disaster. However, due to lack of funding and coordination, the same system did not exist in the Indian Ocean, where the threat of tsunamis was just as high. The United Nations helped found the IOTWC or Indian Ocean Tsunami Warning Center. It works much like its Pacific counterpart, using a network of ocean-bound buoys to detect wave height and strength. Using technical help from Japanese and American groups, the organization included all the countries in the region that were struck by the 2004 tsunami. Training, drills, and evacuations are also coordinated by the IOTWC. With proper preparation and warning systems in place, it is hoped that many lives will be saved from the destruction of any future tsunamis. With populations in South and Southeast Asia continuing to rise, these precautions are more important than ever. Although humans can never prevent such destructive events from happening, we can work to minimize the damage. An electronic buoy monitors the Indian Ocean as part of the IOTWC system. Sources Camp, Vic. "Krakatau, Indonesia." San Diego State University. Pararas-Caryannis, George. "Nar and far-field effects of tsunamis generated by the paroxysmal eruptions, explosions, caldera collapses and massive slope failures of the Krakatau volcano in Indonesia on August 26-27, 1883." The International Journal of the Tsunami Society 4 (2003): 119-221. Accessed February 19, 2013. 8