IS IT WESTERN OR EASTERN PART OF INDONESIA THAT HAS MORE ACTIVE PLATES ACTIVITY ?

The tectonics of Indonesia are very complex, as it is a meeting point of several tectonic plates. Indonesia is located between two continental plates: the Eurasian Plate (Sunda Plate) and Australian Plate (Sahul Shelf); and between two oceanic plates: the Philippine Sea Plate and Pacific Plate. Then, western or eastern part of Indonesia that have more active plates activity?

Order of tectonic in the western part of Indonesia shows the pattern of the tectonic that relatively simpler than the eastern part of Indonesia. The simplicity of tectonic structure is influenced by the presence of the Sunda Shelf that relatively stable. Striking dynamic movement only occurs in Borneo rotation and stretching of Makassar Strait. This can be seen in the pattern of distribution of West Indonesian subduction path . Thing that make eastern Indonesian geological structure more complicated is island arcs that bounded by the ocean with a depth of thousands of meters with trenches in a curved arc that exists between different sharp. Tectonically , eastern Indonesia is the location of the meeting of three tectonic plates, the Pacific Plate moves from east to west, the Australian Plate moving from the southeast to the northwest and the Eurasian Plate are moving from northwest to southeast. The crash among three tectonic plates produces a complex pattern that spreads from the island of Sulawesi, Maluku to Irian Jaya,

In the northern part of eastern Indonesia , the Pacific plate crashed into the west and south of Indonesia . The enormous pressure because of the movement of three earth plates : the Eurasian Plate , the Indian - Australian plate and the Pacific plate that caused the interior of the Earth's plates of the Indonesian archipelago is divided into small parts between the crust that move against each other that limited by active faults . While the western part of Indonesia is relatively stable compared to eastern Indonesia , therefore the islands are larger than those in the eastern region of Indonesia .

In the western region of Indonesia regularity tectonic lines clearly visible. Diping speed of the Indian-Australian continental plate in an average of 7.7 cm / year, relatively oblique dip in parts of Sumatra. This oblique diping produce trenches in the sea and on the land resulted in the Bukit Barisan mountains. In eastern of Indonesia, Pacific Ocean moving at an average speed of 8 cm / year (Sudrajat, 1997) against the Eurasian Plate from the east, so that ripped the earth's crust in Sulawesi with the formation of fragment slides: fault Pulokoro, fracturing Matano, and fault Sorong, etc. Maluku Sea is a clash between the plates of Eurasia-Pacific-the Philippines. This clash led to the formation of double subduction. Sangihe arc dip to the west reaches a depth of 650 km, and Halmahera swooping east to reach a depth of 300 km.

The area surrounding the West Southeast Maluku and Southwestern Maluku is a high earthquake-prone areas. The complexity of the geological conditions and the mixing of subduction of the India-Australia , the Pacific, the Eurasian and the Philippine plate cause the seismicity is more complicated. Whereas the earthquake and tsunami recorded history that had ever happened records that there are 174 tsunamis in Indonesia in 1629-2014, approximately 60 percent occurred in eastern Indonesia.

So, from the data we can conclude that Eastern part of Indonesia has more active plates activity as the location that lies among three active plates.