The current shape of the earth's surface at this time is the result of what happened in the past. This is one of the theories of the History of Development of Geological Sciences
Earth's Layers
Source: Ilmubatugeologi
After the devastating earthquake of 26 December 2004 in Aceh, we do not know which areas will experience similar earthquakes. One thing we know for sure is just a matter of conviction that when earthquakes happen, how much, whether it will cause a tsunami or not, everything is still the secret of God Almighty.
Of all the natural disasters that exist, earthquakes are the most difficult natural to predict. The disaster can occur suddenly without knowing the time. Can be morning, noon, even midnight. The consequences can also cover a very large area with its destructive nature is also remarkable. Earthquakes are a natural phenomenon, even the symptoms that will precede the end of the world.
Tsunami wave illustration in Aceh, December 26, 2004
Source: Wikipedia
In recent years, Indonesia is often hit by an earthquake that caused a lot of victims. Both wealth and soul. Noted, for example, the earthquake in Flores, East Nusa Tenggara, on December 12, 1992, that caused a tsunami wave to drown the island of pigs and killed 2.100 people. Recorded also earthquake and tsunami in Banyuwangi on June 3, 1994, an earthquake in Liwa, earthquake in Kerinci, and finally earthquake and tsunami in Aceh on December 26, 2004.
After the earthquake in Aceh, we do not know which areas will experience this natural phenomenon. Until now humans are only given knowledge to the extent of knowing the position of the quake centers and the magnitude of the earthquake force after the earthquake occurred. From the data collection of earthquakes that have occurred and observe the position of tectonics, new humans are limited to determine which areas are prone to earthquakes. One of them is Indonesia which is among the three major collisions of the world's plates - Eurasia Continental Plate, Indian Ocean-Australian Plate, and Pacific Ocean Plate. We live in the shadow of the earthquake.
From the eyes of faith, we understand everything that happens in nature has wisdom. Our task is to learn the wisdom behind all the events that exist. Our first task is to read and learn from all the wisdom that exists. Reading is not limited to what is written alone, but also read the nature of God's creation of God Almighty so that people understand and understand the language of nature so avoid disaster and destruction.
The frog who keeps the earth stable, the beliefs of the Tibetans
Source: Wikipedia
Back to earthquake problems. How can this natural phenomenon occur? Primitive people believe in the superstition that earthquakes occur because of the gods who carry the earth stiff and fatigue. So when the god moved the earth shook. The Greeks called this earth-carrying god with the name of Atlas. Meanwhile, the Tibetans believe that the earth is borne by a giant frog, if the frog moves the body or head, there is an earthquake. These superstitious beliefs then cause them to make offerings or offer offerings to gods and supernatural beings. There are tribes that even make rituals in the form of animal sacrifices or virgin girls.
Science explains that earthquakes are a natural process of seeking balance. An earthquake occurs due to the release of elastic energy that radiates to the surface of the earth in the form of primary waves (radiating parallel to the direction of the wave propagation) and secondary waves (propagating perpendicularly to the direction of the wave propagation). The primary waves shake the building left and right, while the secondary wave shakes the building up and down (like the movement of the person who pulled the nail using a hammer). Different speeds and directions of these two waves are destructive and make the ground split and the buildings on it collapse.
Banda Aceh City before and after the Tsunami, December 26, 2004
Source: wowkeren.com
The earthquakes have the potential to generate tsunami waves when sudden sea level changes occur. This situation can be observed on the coast in the form of the phenomenon of sea water receded suddenly, the fish floundered, and fishing boats ran aground. In the interval not too long from the time of the phenomenon, in a matter of minutes, the water will return to the sea with great power. As we can see on December 26, 2004, earthquake and tsunami in Aceh, the power of tsunami waves could drown the island, forbade the ship, and destroyed whatever it inflicted.
The earthquake itself is broadly divided into two types, namely volcanic earthquakes and tectonic earthquakes. Volcanic earthquakes are associated with volcanic activity, while tectonic earthquakes are related to movement or displacement of earth layers. Judging from the consequences, tectonic earthquakes are much more powerful, because they cover a wider area and are global. Volcanic earthquakes only affect the area around the volcano only.
Then, will tectonic earthquakes eventually scatter the earth? Clearly, the process of occurrence of various continents as it exists today is preceded by the movement of the plates of the earth.
2 Basic continent of Earth: Gondwana and Laurasia Continents
Source: zmescience.com
According to earth experts, at first, the earth only had one large continent called "Pangea" and one ocean called "Panthalassa". About two million years ago "Pangea" broke into two continents; "Gondwana" located in the south, and "Laurasia" in the north. In subsequent developments, these continents rupture again into the continents as we know them today. Gondwana split into Antarctica, Australia, Africa, South America, and the Indian subcontinent, while Laurasia is divided into Europe and North America. Fractions of these continents are known as the Continental Plate.
Like the continent, the oceans are also expanding and forming oceanic plates which some of the plates are sliding in parallel or pushing each other. The theory of plate movement is known by the name of Plate Tectonic Theory. In theory, it is assumed that the entire planet earth is geologically a unity consisting of plates (imagine like a boiled egg which skin is cracked into several parts). The earth's crust or lithosphere, including the outer part of the earth's mantle, is considered as rigid plates that move one against the other. With speeds ranging from 1-10 centimeters/year or equal to 100 kilometers/10 million years. The plates are limbs of lithosphere that reside on a mobile or mobile layer called asthenosphere. The plates float above the earth's layer, under a heavier crust, but soft due to very high temperatures, just like clouds floating in the air. This reality is very rational and can be proved, we think the mountains just sit in their place but it goes like the way of clouds.
The movement of the earth's plates has been proven by periodically monitoring the Earth's satellites. From the pictures shown it appears that the Arabian Peninsula shifts close to Iran a few centimeters each year. The movement of the Arabian Peninsula is of course along with the movement of the mountains that are above it. Likewise, the continent of Australia continues to shift northward to near southeast Asia.
Movement of plates as mentioned above there is a collision between each other, there is mutually away, and there is only rubbing. Examples of moving plates away are the western Pacific Ocean Plate which shifts towards Asia, while the east shifts eastward. Between the two plates, there is a long crevice of the earth's skin that removes the magma containing the various minerals of the earth's stomach deposited on the plates that move extending in both directions.
Digital relief of the Alps; France, Italy, Switzerland, Germany, Liechtenstein, Austria and Slovenia. Based on SRTM-Data
Source: Wikipedia
Some of the plates are mutually distant, the two contiguous continental plates can lead to folding which is then lifted into the mountains. This phenomenon can be seen exactly from the Alpina mountains in Europe until its extension to the east, then hammered Turkey, Iran, Pakistan, and India. If the collision occurs between continental plates and oceanic plates, then there will be infiltration of oceanic plates down the continental plate. One example of such collisions is the collision between the Indian Ocean-Australia Plate and the Eurasian Plate. In the meeting area of the inner plate are collected elastic energy due to collision or shear between plates. The earthquake occurs when the elastic energy is discharged suddenly.
The mechanism of movement of the plate sharing as mentioned above is thought to be caused by the deepest convection currents inside the earth's mantle. Some geologists assume that the main motion of the plates is affected by the difference in the density and thickness of the earth's crust that protrudes laterally due to the cooling of the earth.
Alpina mountainsSource: Wikipedia
In principle, the plate tectonic theory recognizes six major plates and 14 smaller plates in the world. The plates, among others: Eurasian, Indian-Australian, Pacific, American, African, Antarctic, Filipina, Caribbean, Arabic, and Gorda. Particularly the Indonesian archipelago turned out to be the product of a meeting of 3 large plates. The third "mega plate" flanking the Indonesian archipelago is the Eurasian plate that moves southward, the Indian-Australian Plate moving north, and the Pacific Plate moving westward. This causes the Indonesian territory to have a complex geologic shape and vulnerable to geological disasters such as tectonic earthquakes, tsunami waves, volcanic eruptions, and landslides. Likewise, despite the complexity of Indonesia, many have obtained results in the search for minerals and hydrocarbons.
Source :
- id.wikipedia.org
- Adriansyah, Faizal, 2012, Aceh Laboratorium Bencana, Banda Aceh.
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