Magnitude 6.5 Earthquake beneath Central Papua Province, Indonesia.

The Indonesian Meteorological, Climatological, and Geophysical Agency recorded a Magnitude 6.5 Earthquake at a depth of about 24 km, to the south of the town of Nabire in Central Papua Province, Indonesia slightly before 3.20 am on Friday 19 September 2025, Eastern Indonesian Time (slightly before 6.20 pm on Thursday 18 September, GMT). The event was felt across much of western Central Papua Province and parts of eastern West Papua Province, and is reported to have caused the collapse of the main bridge in Nabire, as well as two houses. Other buildings, including the airport, have recorded minor damage, although no casualties have been reported.

The approximate location of the 18 September 2025 Central Papua Earthquake. USGS.

The tectonic situation underlying the island of Papua is complex, with the island being made up of a number of small tectonic plates being squeezed between the larger Pacific/Caroline and Australian plates. Beneath Central Papua Province the Pacific Plate is being subducted beneath the Australian Plate along the New Guinea Trench, however, this is not a simple tectonic boundary with one plate disappearing beneath another, as a sliver of an older, now almost completely subducted plate caught between the two and being displaced to the west along the Sorong-Yapen Fault. This creates a complex situation in which the various plates stick together until pressure builds up sufficiently to overcome the friction and causes sudden movements we experience as Earthquakes.

(a) Block diagram illustrating kinematic partitioning of oblique convergence (without scale) in northwestern New Guinea. The diagram shows partitioning  as is occurring in the last 4 million years and also notes the timing of major shortening events in the region. Note that shortening in the Lengguru Fold Belt region (including the adjacent Wandamen Peninsula) was replaced by extension after 3 million years ago. Black arrows show GPS vectors. (b) Block diagram showing oblique convergence. Saputra et al. (2023).

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Magnitude 7.0 Earthquake under West Papua.

The Indonesian province of West Papua was hit by a Magnitude 7.0 Earthquake at a depth of 68 km beneath its Central Highlands, slightly after 1.40 pm local time (slightly after 4.40 am GMT) on Saturday 6 April 2013, according to the United States Geological Survey. This is a big, quake, but moderately deep, so it is unlikely to have caused widespread destruction; the United States Geological Survey estimate there is a 35% chance the quake may have led to loss of life. It will have been felt over a large area, and witnesses have reported feeling the quake on Bali. Large Earthquakes in Indonesia have caused major tsunami events in the past, but this is not likely on this occasion as the quake is both deep and on-land.

The epicenter of the 6 April Earthquake (black star) and the areas likely to have suffered the worst damage. Note that the epicenter does not fall within the area likely to suffer the worst destruction, which is in higher mountains slightly to the north. Damage to buildings is only likely within the yellow and green areas, the blue areas are likely yo have felt some shaking. USGS.

The tectonic situation underlying West Papua is complex, with the island being made up of a number of small tectonic plates being squeezed between the larger Pacific and Australian plates. The area affected by the 6 April quake lies on the boundary between the Maoke Plate, which underlies much of West Papua and the Woodlark Plate, which underlies much of the east of the island. Other parts of the island lie on the Bird's Head, Australian and South Bismarck Plates. To the north of West Papua the Caroline Plate is being subducted in the Manus Trench, which is parallel to the northern shore of the island.

The plates underlying West Papua and the surrounding area. Wikipedia.

See also Eruption on Manam Motu, Ash cloud reported over Karkar Island, north of Papua New Guinea, Magnitude 6.8 Earthquake hits Bam Island and Earthquakes on Sciency Thoughts YouTube.

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