2nd English Sector

2 04 2010

The Most Dangerous Disasters in Indonesia


Disaster, bad enough or no is always identical with a serious bad situation. Disasters are events that threaten and disrupt community life caused by natural factors or unnatural factors and human factors that lead to the emergence of the human casualties, environmental damage, property loss, and psychological impact (http://en.wikipedia.org/wiki/Disaster). In this case, the disaster meant here is a natural disaster. A natural disaster is a physical event that occurs due to natural events like earthquakes, volcanic eruptions and landslides. Humans can’t manage an emergency situation so that a human loses of property and infrastructure, even until death. Losses due to natural disasters depend on the ability of humans to prevent or avoid disasters. Many natural disasters that occur in Indonesia because the position of Indonesia is very complex based on the point of view of geologist. Disasters that occur in Indonesia are something like earthquakes, tsunamis, volcano eruption, landslide, floods, storms, forest fires, etc. From various kinds of natural disasters, earthquakes, volcano eruptions, and landslides are dangerous disasters that often happen in Indonesia.

There are many reasons that earthquake, volcanic eruption, and landslide are dangerous disasters that often happened in Indonesia.

I. Indonesia Has a Rock Basement That Always Moves Every Year

Earth is made up of several layers of rock. The outermost layer of rock is the crust. The crust is divided into several sections and then the crust moves known as plate tectonic movement. Plate tectonics is each plate move or less independently and grinds against the others, concentrating most deformation, volcanism, and seismic activity along the periphery (Parker, 1984). On the other hand, plate tectonics is a scientific theory which describes the large scale motions of Earth’s lithosphere (http://en.wikipedia.org/wiki/Plate_tectonic).

Plate tectonic is called a plate because the thickness reaches only about 100 kilometers while the length can reach thousands of kilometers. On earth there are seven major tectonic plates and several small tectonic plates. They move relative into each other at plate boundaries, divergent (spreading), convergent (collision), or transform. Earthquakes, volcanic activity, mountain formation, and oceanic trench formation generally occurs in areas along plate boundaries.

A. the Area is Among Three Plate Tectonics

In Indonesia there are also large tectonic plates that cause the rock basically to move every year. This is because Indonesia becomes an archipelagic state. Plate tectonics is located along the southern coast of Sumatra Island, the southern coast of Java Island, the southern coast of Bali Island, the southern coast of Southeast Nusa Island, and West Papua Island also the eastern of Sulawesi Island. Tectonic plates that move in the territory of Indonesia, namely: Eurasian plate, Indo-Australian plate, and Pacific plate.

–                        Eurasian plate

The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia (http://en.wikipedia.org/wiki/Eurasian_plate)

–                        Indo-Australian plate

The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters (http://en.wikipedia.org/wiki/Indo-Australian_Plate).

–                        Pacific plate

The Pacific Plate is an oceanic tectonic plate beneath the Pacific Ocean (http://en.wikipedia.org/wiki/Pacific_plate). In the other hand, the Pacific Plate is a continental margin typified by that of the western Pacific where oceanic lithosphere descends beneath an adjacent continent and produces an intervening island arc system (Parker, 1984).

B. the Area is on Subduction Zone

Each tectonic plates moves relative to each other to achieve a dynamic balance. The meeting of tectonic plates is called a subduction zone. Result from collisions between tectonic plates is an earthquake which is referred to as tectonic earthquakes. This is the answer to the question of why earthquakes frequently occur in Indonesia.

In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth’s mantle, as the plates converge (http://en.wikipedia.org/wiki/Subduction). According to Parker (1984), subduction is the process by which one crustal block descends beneath another, such as the descent of the Pacific plate beneath the Eurasian plate along the Sumatra Trench. A subduction zone is an area on Earth where two tectonic plates move towards one another and subduction occurs (http://en.wikipedia.org/wiki/Subduction). Still according to wikipedia.com, rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately 2 to 8 centimeters per year (about the rate a fingernail grows).

II. Indonesia Has a Volcanic Arc from West until East

In the territory of Indonesia there are many volcanoes ranging from Aceh on the Sumatra Island to the west of the Papua Island. This is known as volcanic arc. This is the reason that volcanic eruptions are dangerous disasters that often happened in Indonesia.

A. Melting of Rock Basement Because of Subduction Process

Many volcanoes in Indonesia are due to subduction processes that occur in the basement rocks of Indonesian territory. Because the subduction process is thaw the bedrock so that the molten rock rose into the surface and form volcano morphology on the surface of the earth. This is evidenced by the formation of a volcanic arc relatively parallel to the subduction zone.

B. Magmatic Activity

Magmatic activity is the movement of magma within the bowels of the earth because of pressure differences and temperature differences.

As a result of magma movement is could be an earthquake and it called volcanic earthquakes. Then if the movement of magma is very large and able to reach the surface there will be a volcanic eruption. Magmatic activity is caused by two main things, namely:

–                        Pressure difference

–                        Temperature difference


Natural disasters are a natural phenomenon that cannot be avoided. These phenomena occur in almost any area. Wherever we live, natural disasters will always be around us because we live in nature. Natural disasters are caused by natural disasters on our control or natural disasters beyond our control. Natural disasters may be the changes the earth’s surface, climate change, and various natural phenomena that can lead to other natural disasters. Indonesia is a large country with large natural disasters and non-natural disasters. Either volcanic earthquakes or tectonic earthquakes, landslides or scientifically called mass movements, and volcanic eruptions is natural disasters of the greatest and most often occur in Indonesia and we really need to aware of it.



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