The Eruption of Toba - Case Study Example

The Eruption of Toba Table of contents Introduction………………………………………………………………………….…… 3 Geological setting of Toba…………………………………………………………………3 The Toba super-eruption………………………………………………………………..…5 The Toba catastrophism theory…………………………………………………………...6 Conclusion………………………………………………………………………………....8 The Eruption of Toba Introduction Since the formation of the earth, several natural events have taken place. Events such as faulting, volcanic eruptions, and folding among others have been in the front line in shaping the earth. Volcanic mountains were formed when heated larva from underneath the ground surface erupted onto the ground surface. The various sizes of the volcanic mountains formed are as a result of varied amount of larva produced and the topography of the place at which the eruption occurred. Depending on the density of the larva and the force of eruption, some volcanic materials may not form a mountain but other features such as volcanic plateaus or plains. Based on the energy build up, some eruptions are very violent and consequently destroy many vegetation and animal species. One such eruption is the Toba super-eruption which occurred between 69,000 and 77,000 years ago. The event is called a super-eruption because it had a volcanic explosivity index of magnitude 8. The volume of the magma material released during the eruption was approximately between 2000 and 3000 cubic kilometers. It was more than 100 times more than the largest volcanic eruption that have occurred in the recent times. This paper talks about the Toba super-eruption and its consequence. Also, it explains the theories that were formed based on it. Lastly, it explains the tectonic setting of the region around which the eruption occurred. Geological Setting of Toba Most of the volcanic activities of the world are factor of the geological setting of the place of occurrence. The same case applies to earth quakes. Over the years, the South Asian region has witnessed several earth quakes. This is the same area around which the Toba super-eruption occurred. The Toba super-eruption occurred near Sumatra in Indonesia as noted by Arion (2008). The place of eruption is currently occupied by Lake Toba. It resulted in the deposition a volcanic ash which spread to the whole of South Asia. Figure 1 shows the map of the region where the super-eruption occurred. Fig. 1: The region where the super-eruption occurred Toba volcano is found in northern Sumatra and is next to Lake Toba. This area is considered to be the most seismically active in the world. It sits on the intersection of two tectonic lineaments (Arion 2008). This area served as the epicenter for the catastrophic tsunami earth quake of 2004. The entire region is prone to earth quakes as it lies near Sumatra fracture zone. Lake Toba is positioned near the Sumatra Fracture Zone. This is a fault line which runs through Sumatra center. The Java and Sumatra volcanoes form part of Sunda Arc (Arion 2008). At this point, the Indo-Australian Plate lies under the Eurasian Plate. This makes the area around Lake Toba active. The scientists have pointed out that the tectonic plates boundary in this region is the genesis of the earth quakes and eruptions witnessed in the recent past. The same case applies to the Toba super-eruption. The epicenter of most of the earth quakes in the region is near the Sumatra center (Arion 2008). There have been minor eruptions reported near Toba since the super-eruption occurred. The volcanic materials which were deposited during the super-eruption collapsed to form a caldera. This is the biggest caldera in the world. The edges of this caldera have been active over the years (Williams 2011). The fact that the Sumatra region lies in the area of weakness makes scientists have an easy task. The tectonic boundary could allow hot materials to emerge into the surface. The pressure build up of the volcanic material made it possible for the eruption. The extent of the explosion was determined by the inability of the earth tectonic layers to contain the material. Though there have been no signs of occurrence of an eruption of the same magnitude, the frequent earth quakes makes it hard to rule out an eruption. The Toba Super-eruption The Toba super-eruption was one of the biggest eruptions in history. It was felt by the whole of the universe due to its far reaching consequences. The region around which it occurred is seismically active (Natural historian 2012). In addition, the fault line that exists in the region made it possible for the eruption of a big magnitude. The Toba super-eruption was the last eruption of Toba out of the three which occurred over the last 1 million years. It led to formation of 100km by 30km caldera complex which is the biggest in the universe (Chesner 2011). The Toba super-eruption deposited 15 cm thick ash-layer all over South Asia (Gatti et al 2011). The records of the global climatic changes show that the Toba super-eruption occurred at approximately 74, 000 years ago. This information rhymes with the Antarctic ice and Greenland cores (Chesner 2011). This is also the age of the Toba tuff sediments. The dating methods used in this exercise proved beyond any reasonable doubt the age of the sediments by comparing them with other deposits across the globe (Gatti et al 2011). The feature that resulted from the eruption is no longer considered to be volcano because it was blown to form a caldera. This caldera is filled with water to form a large lake of about 100km x 30km (Chesner 2011). The Toba super-eruption occurred in series of explosions which threw larva material of about 2800 cubic kilometers into the air. Estimates range between 2000 and 3000 cubic kilometers (Chesner 2011). This makes it to be the largest sing volcanic eruption in history.      Up to date, it is hard to comprehend the extent of Toba super-eruption. Near the volcano, the ash layer measures about 1000 feet thick and spreads to over 2000 miles away from the volcano (Gatti et al 2011). It spreads all over the Indian subcontinent and Southeast of Asia. This vast hole which resulted and which is now Lake Toba is an indicator that the eruption was massive. The ash that resulted from this eruption is found even in the South China Sea and Indian Ocean (Chesner 2011). Researchers have estimated that the Toba super-eruption coincided with the last glacial period onset. It is believed to cause the decrease in the average global temperature by about 3 to 5°C (Williams 2011). This temperature decrease accelerated the temperature transition for the last glacial cycle from warm to cold. Further research shows that the super-eruption was followed by high dust deposition and 1, 000 years of lower temperatures. This notion is supported by scientists who claim that the eruption of this magnitude is characterized with emission of noxious gases and widespread ash fall (Gatti et al 2011). Presence of these gases in the atmosphere has far reaching consequence on weather and climate. The living organisms could not cope with the new climatic conditions without adjustments. Many animals and plant species adapted to the new conditions so as to survive. This explains why the Toba super-eruption was a threat to various species of animals and plants (Williams 2011). The Toba Catastrophism Theory Almost every incidence with far reaching consequences in the universe has a theory explaining it. The Toba super eruption is no exception as the Toba catastrophism theory was postulated to explain its consequences on humans. The Toba Catastrophism Theory is based on the adverse effects of the Toba super-eruption. Around the time of the occurrence of the super-eruption, the human population was on a steady decline as noted by Drinnon (2011). This situation was made worse by the eruption as it abruptly changed climatic and weather conditions. Scientists have noted that the human race was almost wiped out of the universe by the Toba super-eruption (Drinnon 2011). This is because it was linked to the genetic bottleneck in evolution of human in the period about 50,000 years ago. The eruption had severe effects on the global climate which threatened human races. This was indicated by severe reduction in the human population. The current human population is believed to have come from few people who remained after this severe decline. The lowest human population was witnessed about 70, 000 years ago (Drinnon 2011). This is the period about which the Toba super-eruption occurred. It resulted into destruction of vegetation and consequently caused ecological disaster. The destruction of vegetation was accompanied by severe draught in the monsoonal regions and tropical rainforest belt. The volcanic winder of about 10 years which resulted from the eruption was detrimental to sources of food (Drinnon 2011). Population of many species was reduced. The changes witnessed among people are suggested to have occurred due to the effects of the eruption. From the origin of human being, there have been gradual changes but they are believed to have been suppressed by the Toba eruption. Many people are also believed to have been wiped away by the Toba super-eruption. Archaeologists have found some remains of the human being and other organisms under the ash layers in India (Natural historian 2012). There was also widespread deforestation in the area and the global community at large. This made people to adapt to new ways of life.  The theory is challenged by the fact that it is hard to determine regional effects of the eruption to global climate. This may mean that some places were not adversely affected as other and therefore the decrease of the population may not have due to the Toba super-eruption. The Toba catastrophe theory however suggests that, human population bottle neck occurred 70, 000 years ago (Natural historian 2012). This led to decrease of human population to about 15,000 individuals (Drinnon 2011). This occurred because the eruption caused widespread environmental changes. It also caused volcanic winter. These changes hindered functionality of some genes such as mitochondria DNA, some nuclear genes and Y-chromosomes. This hindered human reproduction in some way although it was not very detrimental. People who survived the Toba super-eruption migrated to other regions after the climatic conditions stabilized. The research shows that most of the surviving human population was in Africa. These people migrated later and occupied the entire world. Conclusion Toba super-eruption is one of the biggest eruptions in the history of the world. It occurred near Sumatra in Indonesia. The resulting volcanic feature was then blown to form a caldera which was filled with water to form Lake Toba. It led to displacement of volcanic materials of about 2800 cubic kilometers. These materials spread all over the South Asia and some volcanic ash settled at the bottom of Indian Ocean and Arabian Sea and in South China,. The eruption destabilized the global climatic conditions and weather patterns and directly led to the destruction of animal and plant species living on earth. As a result of the super-eruption, humans and other organisms had to adapt to new ecosystem. It threatened the human species by destroying sources of foods and creating unfavorable conditions in the ecosystem. This is explained by the Toba catastrophe theory. The only surviving human species were found in Africa and migrated later to occupy the entire world. The place of occurrence of the eruption is bordered by a big fault line which served as the weak line for underground materials to emerge onto the surface. The area is also characterized by the occurrence of frequent earth quakes in the recent times. This makes people not to rule out the possibility of occurrence of a similar eruption. The eruption also resulted in the formation of the biggest caldera in the world. The materials and the ash produced covered the whole of South Asia and nearby seas and oceans. The eruption also led to a volcanic winter which greatly lowered global temperatures. The lowering of temperatures and destruction of vegetation led to destruction of many species of plants and animals. This left every living creature affected. References Arion (2008). Lake Toba Geology. Retrieved February 19, 2014 from http://laketoba-samosir.blogspot.ca/2008/07/lake-toba-geology.html Chesner, C. A. (2011). The Toba Caldera Complex, Quaternary International. Department of Geology/Geography, Eastern Illinois University, United States . Retrieved February 19, 2014 from http://www.geo.mtu.edu/~raman/VBigIdeas/Supereruptions_files/Toba%20QI.pdf Drinnon, D. (2011). Toba Bottleneck: Toba catastrophe theory. Retrieved February 19, 2014 from http://frontiers-of-anthropology.blogspot.ca/2011/02/toba-bottleneck.html Gatti, E., Durant, A.J., Gibbard, P. L., Oppenheimer, C. (2011). Youngest Toba Tuff in the Son Valley, India: A weak and discontinuous stratigraphic marker. Retrieved February 19, 2014 from http://hal.archives-ouvertes.fr/docs/00/70/71/53/PDF/Gatti-QuaternaryScienceReviews-2011.pdf Natural historian (2012). The Toba Super Eruption: A Non-Flood Catastrophe – The Artifacts Say Yes!. Retrieved February 19, 2014 from http://thenaturalhistorian.com/2012/05/04/toba-tuff-adam-super-volcano-flood-geology/ Williams, M. (2011). The w73 ka Toba super-eruption and its impact: History of a debate Geography, Environment & Population. University of Adelaide, Australia. Retrieved February 19, 2014 from http://www.segemar.gov.ar/bibliotecaintemin/INTEMINSEGEMA RHEMEROTECA/%281040-6182%29quaternaryinternational2582012/19-29.pdf Read More