THE TRIGGERS OF SEDIMENT - RELATED DISASTER

1. INDONESIA SITUATED BETWEEN TWO VOLCANIC BELT

The location of Indonesia archipelagos in inside circum Pacific Volcanic Mobile Belt and Trans Asiatic Volcanic Belt, thus approximately 17% volcanoes in the world spread all over Indonesia. It is recognized by three volcanic zone that can be found here; there are Alphine Mountains Zone (Sunda Mountains Zone), East Asiatic Zone (Minahasa-Sangir-Ragay), and Australian Circum Zone (Halmahera-Ternate Zone). This formation is called volcanic belt.



2. INDONESIA LOCATED IN FAUTL REGION
Some part of Indonesia are active fault areas; this certain area is very unstable because it always moves. So that in Indonesia earthquake happens very often. It shake and makes particles of soil separated or in other world, it becomes less cohesion. In this condition those particles of soil will be easily washed out by water. That is how sediment-related disaster generated.

Tectonic Plate, (Simanjuntak, 1994)

3. MOUNTAINOUS TOPOGRAPHY
As mentioned before, Indonesia is located between two volcanic belt; the consequence is most of its topography mountainous with very steep slope. In some area the inclination is more than 30 degree, where is very potential for sediment-related disaster occurred.
4. DISTANT COASTAL LINE
As an archipelago country, Indonesia has very long coastal line. The abrasion of coastal line and tsunami is the matters to be concerned because beside disaster as primary effect, it may also decrease Indonesia territory.

5. HIGH RAINFALL
Indonesia is one of countries with very high rainfall. Average cumulative rainfall is about 2,000 mm per year. Furthermore, in mountain area it is reached around 4,000 mm per year. So that Indonesia becomes one of the water richest countries in the world.
















6. GLOBAL WARMING AND CLIMATE CHANGE
Climate change has caused severe climate cycles, it is notice that the temperature of earth surface in 1970 to 1980 is relatively higher previews years but in 1980 to 1990 it became colder. The cycles still continue, at the beginning of 21st centaury the earth temperature has increased again and so the temperature of atmosphere is, the increment is about 3o C. This phenomenon is related to many complex factors, whether natural or human factors. This uncertain climate behavior may also triggers natural disaster.


7. HUMAN DOMINATION
Indonesia is one of the high populated countries in the world. As the population grows, the demand for settlement will also increase. This situation will give a great effect in environment changing, such as nature balance, human relationship to other, and relationship between human with nature it self. In other world, human plays important role on environment changing.

Meanwhile, almost all natural disaster that recently occurred is as the result of irresponsible human activities that disturb nature balance. For example erosion caused by improper method of agriculture and pollution caused by vehicles, industries, etc,.

EL Nino and La Nina are some evidences related to phenomenon of climate change. In Indonesia it is recognized by typhoon or cyclone which is more frequently happened. By local people it is called Kololilimbun or Puting Beliung. This cyclone is always followed by heavy rain, and then the water will flush away the materials that is brought by it, which is consist of sediment, trees, and woods, those materials give more damages than pure water does.




.