Sunda Plate
The Sunda Plate is the 11th-largest of the 52 plates in the PB2002 plate model, covering 8.9 million km² (3.4 million sq mi), or 1.7% of Earth’s surface. Southeast Asia: the Malay Peninsula, Thailand, Cambodia, southern Vietnam, Borneo, Sumatra, Java and most of the Philippines.
- Area
- 8.9 million km² (3.4 million sq mi)
- Share of Earth’s surface
- 1.7%
- Speed across the plate
- 2.9 to 4.8 cm a year (1.2 to 1.9 in)
- Direction at its center
- Toward the east
- Length of its edges
- 14,030 km (8,720 mi)
- Neighboring plates
- 9
- Edges by type
- 62% convergent · 11% divergent · 26% transform
- Volcanoes on it
- 87 active in the past ~12,000 years
What happens at its edges
The Australian Plate sinks beneath its southern edge along the Sunda Trench, one of the world’s most active subduction zones, which feeds the volcanoes of Sumatra and Java, including Krakatau and Merapi.
To the east it meets the Philippine Sea Plate and a mosaic of small plates around the Molucca and Banda seas. Many simpler maps treat it as part of the Eurasian Plate.
How fast it moves, and which way
At its center (5.0°N, 111.1°E) the Sunda Plate moves about 4.0 cm (1.6 in) a year toward the east. Because a plate turns around a pole rather than sliding in a straight line, the speed changes across it: from 2.9 cm (1.2 in) a year to 4.8 cm (1.9 in) a year, with an area-weighted average of 4.0 cm a year. That average makes it the 28th fastest of the 52 plates.
These figures are measured against the average motion of all the plates together (the “no-net-rotation” frame), which is how plate speeds are usually quoted. Measured against the Eurasian Plate instead, the Sunda Plate moves about 2.1 cm (0.8 in) a year toward the east-northeast at its center.
In the model it rotates about a pole at 44.6°N, 73.5°W at 0.468° per million years. The speeds are averages over years to millions of years of measurement; earthquakes move the ground near a boundary in sudden steps instead.
Neighboring plates and boundaries
Its edges run for 14,030 km (8,720 mi): 62% convergent, where plates move together; 11% divergent, where they move apart; and 26% transform, where they slide past each other. It sinks beneath the Philippine Sea Plate, Molucca Sea Plate and Banda Sea Plate at subduction zones. The Australian Plate, Philippine Sea Plate and Molucca Sea Plate sink beneath it.
| Neighbor | Shared edge | Boundary types | Relative speed |
|---|---|---|---|
| Australian Plate | 3,290 km (2,050 mi) | Convergent 100% | 5.8 cm a yearup to 6.9 cm |
| Philippine Sea Plate | 2,880 km (1,790 mi) | Convergent 78% · Transform 22% | 10.0 cm a yearup to 10.8 cm |
| Eurasian Plate | 2,030 km (1,260 mi) | Convergent 56% · Transform 29% · Divergent 15% | 2.6 cm a yearup to 2.7 cm |
| Burma Plate | 1,780 km (1,110 mi) | Divergent 61% · Transform 39% | 4.3 cm a yearup to 5.7 cm |
| Molucca Sea Plate | 1,330 km (820 mi) | Convergent 66% · Transform 34% | 2.6 cm a yearup to 4.7 cm |
| Banda Sea Plate | 980 km (610 mi) | Convergent 66% · Transform 34% | 1.8 cm a yearup to 3.4 cm |
| Yangtze Plate | 910 km (560 mi) | Transform 53% · Convergent 37% · Divergent 10% | 1.5 cm a yearup to 1.5 cm |
| Timor Plate | 420 km (260 mi) | Transform 100% | 4.1 cm a yearup to 4.1 cm |
| Bird’s Head Plate | 410 km (260 mi) | Convergent 54% · Divergent 28% · Transform 18% | 10.7 cm a yearup to 10.7 cm |
Relative speed is how fast the two plates move against each other along their shared edge, averaged over its length.
Countries and territories on the Sunda Plate
4 lie entirely on it; the other 6 are split between plates. The share is the part of each country’s land on this plate.
- Indonesia about 63%
- Malaysia all
- Thailand about 62%
- Philippines about 81%
- Cambodia all
- Vietnam about 54%
- Laos about 32%
- Myanmar about 5%
- Brunei all
- Singapore all
Volcanoes on the Sunda Plate
The Smithsonian Global Volcanism Program lists 87 volcanoes on this plate that have been active in roughly the past 12,000 years. The most recent eruptions on record:
Where the edges are blurred
Parts of this plate lie in the Ninety East-Sumatra, Persia-Tibet-Burma and Philippines zones, which the model marks as broad belts of deformation rather than sharp plate edges. There the motion between plates is spread over many faults, and a single boundary line is a simplification.
Sources
Outline, area, boundary types and motion: Bird, P. (2003), An updated digital model of plate boundaries, Geochemistry Geophysics Geosystems, 4(3), 1027, doi:10.1029/2001GC000252. Released by its author into the public domain (CC0 1.0). Areas are the model’s published figures; speeds, directions, boundary lengths and countries are calculated from its outlines, boundary steps and rotation poles.
Volcanoes: Global Volcanism Program, Smithsonian Institution, Volcanoes of the World (v. 5.4.0). Country outlines: Natural Earth.