Tectonic Map of Indonesia, Source : www.arif652.wordpress.com
Tectonically, Indonesia is located on the active plate
margin. flanked by three large plates. two of which are oceanic plates, the
Indo-Australian oceanic plate which is located in the south, the Pacific Plate
is located in the east, and one continental plate is the Eurasian continental
shelf in the North part. The meeting of three tectonic plates produces a unique
framework to form islands which are in Indonesia and surrounding areas
(Malaysia, Philippines and others). In Indonesia, there are 17,508 islands that
are a result of meeting these three large plates. Consists of large islands
such as Sumatra, Kalimantan / Borneo, Java, Sulawesi, Maluku and Irian (Papua
New Guinea). While the rest of the islands are small to medium size such as
Bali, Lombok Island, Thousand Islands, Mentawai Islands, We Island, etc.
In this article, the authors only focused discussion, to the
resulting impact. Be it positive or negative. While the discussion of the
general tectonic framework of several islands that are considered fairly
representative of the tectonic structure in Indonesia, only in the form of an
introduction as a reference. so that, the reader can follow the flow of this
paper. Discussion of the details will be discussed in the next article with a
special category.
1 Tectonic Framework of Sumatra Island and Surrounding area:
Sumatra Island has a land area of 473.481 km2, which is
converging belt between the Indo-Australian plate ocean, with the Eurasian
continental plate with the type of oblique (angled). Indo-Australian plate
under the Eurasian plate crushed on Azzimuth (Direction) N 200 E with average
speed 6-7 cm / year. This convergence also causes rotation of the island of
Sumatra, which originally had the East to West direction (E - W) into Southeast
to Northwest (SE - NW) starting from the Eocene - Oligocene (See Geological
time scale) with a clockwise direction of rotation. This also indicates an
increase of occurrence of horizontal movement by the Sumatran fault.
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| Tectonic of Sumatra, Source : www.ptbudie.wordpress.com |
Various lane complexity generated by this convergence, has
two conflicting effects when seen from the resultant effect on the lives of the
people in it, including:
a. The positive impact and benefit
- The formation of an active fire mountain arc that
stretches from West to East Sumatra. This was followed by the formation of a
variety of primary metal mineral mineralization system, such as: gold, silver,
copper, etc., which have a high economic value.
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| Mineralization System, Source : www.geolamanyofan.blogspot.com |
- The formation of multiple systems basins in the island of
Sumatra. This basin is formed and deposited as a place of hydrocarbons, such as
oil and gas. Some metal minerals that are plaser, such as gold plaser, tin
plaser, and non-metallic mineral deposits and rock produced by weathering
processes, sedimentation, and evaporation. Such as quartz sand, gypsum, talc,
coal and limestone.
- The results of an active volcano on the island of Sumatra
in the form of vomit lava and pyroclastic hurl high nutrients, can increase
soil fertility. So good for soil cultivation activities in the island.
- A range of mountains located on the island of Sumatra, is
part of the arc volcanic mountain world (Ring of Fire). Have a high tourism
value as a recreation. One of the mountain which became a tourist destination
both foreign tourists and domestic travelers is Mount Kerinci (3.805 masl /
12,484 ft) with type Statovulkano. This mountain is the highest active volcano
in Indonesia and the second highest mountain in Indonesia After Jayawijaya summit
(Carstensz Pyramide).
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| Krinci Mountain, Jambi Province, Sumatra, Indonesia, Source : www.look-outside.blogspot.com |
- Tectonic Framework of the Sumatran island and set up a
stable zone order unstable zone. In these stable zones, are zones that can be
developed as a residential place, as well as the development of vital state
assets, such as the construction of nuclear power plants, airports construction
of commercial and non-commercial and others.
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| Kualanamu International Airport, North Sumatra, Source : www.uniqpost.com |
b. Negative Impact and Adverse
- With its many active volcanoes number, the greater the
potential for volcanic eruption on the island of Sumatra, which is harmful.
This was evident after Mount Sinabung (North Sumatra, Indonesia) has erupted 7
times since August 2010 (id.wikipedia.org). which has claimed many lives.
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| Sinabung Eruption, North Sumatra, Source : www.sumutpos.co |
- The eruption of the volcano, potentially inviting volcanic
earthquakes. This occurs due to the release of energy / force abruptly due to a
high pressure magma broke through rocks around it. In theory, this type of
earthquake is local. With the extent of the vibration / shock, influenced by
the strength of the eruption. But it was likely this type of regular seismic
casualties or material losses..
- Potential Earthquake Tectonics. This is the kind of
earthquake that are most harmful to human civilization. In contrast with the
volcanic earthquakes, tectonic earthquakes are regional, with wider coverage.
Even up to hundreds of kilometers. Each region has a different effect, where
the area is divided into several zones based on the MMI scale (Modified Mercally
Intensity). This type of earthquake can also trigger other disasters, such as
volcanic eruptions, volcanic earthquakes, tsunamis, landslides etc.. Not
infrequently this type of earthquake claimed many lives.
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| Earthquake in Padang, West Sumatra 2009, Source : seocool.blogspot.com |
- The potential for a tsunami. Still remember the tsunami in
Aceh Province and parts of North Sumatra on December 24, 2004? yes .. it is one
of the world's most powerful disaster, with casualties in the hundreds of
thousands. In fact, not just Indonesia who are victims of ferocity. Other
Countries bordering the Indian Ocean are also affected. such as Malaysia,
Thailand, India, Sri Lanka, even reaching the East Coast of Africa. Tsunamis
can be triggered by several causes. Among them, tectonic or volcanic earthquake
with epicenter in the sea / ocean, underwater volcanic eruptions, submarine
landslides, and due to hit the meteor that crashed in the sea / ocean.
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| Aceh Tsunami Tragedy, Desember 2004, Source : www.ibtimes.co.uk |
- The potential for ground movement. Disasters of this type
is not as powerful as the above disasters. However, this type of disaster still
cause harm to the people who live around it. The cause of this disaster varies,
but some of the main factors that lead to this disaster are: degrees / percent
slope, type of lithology (rock), the level of rainfall and vegetation in the
vicinity.
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| Houses destroyed by a landslide, Deli Serdang, North Sumatra, Source : m.menit.tv |
Disasters on the offensive. Both the areas hit by the
disaster that directly, or indirectly. Losses incurred manifold. Starting from
death or disability, loss material such as building damage, as well as the
nature of psychology such as: fear, psychiatric disorders up / insane.
to be continued...
