Earlier theory

The Molucca Sea Plate (also Molucca Sea Microplate) was theorised to be a small tectonic plate carrying northern Sulawesi

Sulawesi

Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...

, the Molucca Sea

Molucca Sea

The Molucca Sea is located in the western Pacific Ocean, within the country of Indonesia. The region is rich in coral and has many diving sites.-Location:...

 and a portion of the Banda Sea

Banda Sea

The Banda Sea is a sea in the Maluku Islands of Indonesia, technically part of the Pacific Ocean but separated from it by hundreds of islands, as well as the Halmahera and Ceram Seas...

 in a region littered with numerous small plates. The theory suggested a subduction zone lies along its northern border with the Sunda Plate

Sunda Plate

The Sunda Plate is the tectonic plate on which the majority of Southeast Asia is located. It was formerly considered a part of the Eurasian Plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia...

. A small divergent boundary

Divergent boundary

In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts which produce rift valleys...

 exists along the Sulawesi part of the border with the Banda Sea Plate

Banda Sea Plate

The Banda Sea Plate is a small tectonic plate underlying the Banda Sea in southeast Asia. This plate also carries a portion of Sulawesi Island, the entire Seram Island, and the Banda Islands. Clockwise from the east it is bounded by the Bird's Head Plate of western New Guinea, Australian Plate,...

 and transitions into a convergent boundary as it bisects the Banda Sea

Banda Sea

The Banda Sea is a sea in the Maluku Islands of Indonesia, technically part of the Pacific Ocean but separated from it by hundreds of islands, as well as the Halmahera and Ceram Seas...

; the rest of the borders being transform boundaries.

Current theory

More recent scientific studies suggest the Molucca Sea Plate has been totally subsumed by the Halmahera Plate

Halmahera Plate

Halmahera Plate has recently been postulated to be a microplate within the Molucca Sea Collision Zone of eastern Indonesia.-Regional tectonics:...

 and the Sangihe Plate

Sangihe Plate

Sangihe Plate has recently been postulated to be a microplate within the Molucca Sea Collision Zone of eastern Indonesia.-Regional tectonics:...

, so that no portion of the Molucca Sea Plate remains exposed to the Earth's surface. The tectonic setting of this region is unique in that it is the only global example of an active arc-arc collision consuming an oceanic basin via subduction in two directions, between microplates Halmahera Plate and Sangihe Plate.
To the Southeast is the Sorong Fault

Sorong Fault

Sorong fault also is an active, broad zone of inferred left lateral shear at the triple junction of the Australian plate, Eurasian plate, and Pacific plates, where many plate fragments exist, such as the Philippine Sea Plate, Bird's Head Plate, Halmahera Plate and the Molucca Sea Plate. It has...

, a major lateral east-west fault in the region which separates Bird's Head Plate

Bird's Head Plate

The Bird's Head Plate is a minor tectonic plate incorporating the Bird's Head Peninsula at the western end of the island of New Guinea. Hillis & Müller consider it to be moving in unison with the Pacific Plate. Bird considers it to be unconnected to the Pacific Plate. The plate is separating from...

 and Halmahera Plate. This theory is more fully discussed in the article Molucca Sea Collision Zone

Molucca Sea Collision Zone

The Molucca Sea Collision Zone is postulated by paleogeologists to explain the tectonics of the area based on the Molucca Sea in Indonesia, and adjacent involved areas.-Tectonics:...

.

Large earthquakes frequently strike this area sometimes triggering tsunami

Tsunami

A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

s.

Recent large quakes (>6.0) in region

• June 13, 2011 - 6.2 Molucca Sea
• Feb 11, 2009 - 7.2 Kepulauan Talaud
  Talaud Islands
  Talaud Islands is a group of islands located north of Sulawesi island in Indonesia, northeast of the Sangihe Islands...
  
  
• Sep 10, 2008 - 6.6 180 km south of Manado on Sulawesi
  Sulawesi
  Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
  
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• July 26, 2007 - 6.9 Molucca Sea
• Mar 17, 2007 - 6.5 Molucca Sea
• Jan 21, 2007 - 7.5 Molucca Sea, 5 deaths
• May 19, 2006 - 6.3 Molucca Sea
• Dec 21, 2005 - 6.3 190 km south of Manado
  Manado
  Manado is the capital of the North Sulawesi province of Indonesia. Manado is located at the Bay of Manado, and is surrounded by a mountainous area. The city has about 405,715 inhabitants, making it the second-largest city in Sulawesi after Makassar...
  
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