The 1953 Suva earthquake occurred on 14 September at 00:26 UTC near

Suva Suva () is the capital and largest city of Fiji. It is the home of the country's largest metropolitan area and serves as its major port. The city is located on the southeast coast of the island of Viti Levu, in Rewa Province, Central Divi ...

Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...

, just off the southeast shore of

Viti Levu Viti Levu (pronounced ) is the largest island in the Republic of Fiji. It is the site of the nation's capital, Suva, and home to a large majority of Fiji's population. Geology Fiji lies in a tectonically complex area between the Australian P ...

. This

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

had an estimated magnitude of 6.8 and 6.4. The earthquake triggered a coral reef platform collapse and a submarine landslide that caused a

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

. Eight people were reported killed; a wharf, bridges, and buildings were severely damaged in Suva.

Tectonic setting

Fiji lies in a complex tectonic setting along the boundary between the

Australian Plate The Australian Plate is a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when India broke ...

and the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...

. Southwards from Fiji the Pacific Plate is

subducting Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

beneath the Australian Plate along the Tonga Trench forming the

Tonga Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesian country and archipelago. The country has 171 islands – of which 45 are inhabited. Its total surface area is about , scattered over in ...

Ridge

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alon ...

system and the Lau Basin back-arc basin. To the southwest of Fiji the Australian Plate is subducting beneath the Pacific Plate forming the

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of no ...

Ridge island arc system and the North Fiji back-arc basin. Hence, the region has undergone a complex process of plate convergence, subduction, and arc volcanism from the Middle

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

to the Early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 Many of the larger islands, such as Viti Levu, are of volcanic origin. Volcanism still exists, and there are

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

volcanos in Fiji. The Fiji Platform lies in a zone bordered with active extension fault lines around which most of the shallow earthquakes were centered. These fault lines are the Fiji Fracture Zone (FFZ) to the north, the 176° Extension Zone (176°E EZ) to the west, and the Hunter Fracture Zone (HFZ) to the east.

Earthquake

The earthquake lasted between 25 and 30 seconds and had an estimated magnitude of 6.75 on the surface wave magnitude scale. The calculated focal mechanism is consistent with slightly oblique dextral (right lateral) strike-slip on a NW-SE trending fault plane, matching the orientation of other fault planes measured in the area and a marked bathymetric lineament. The fault parameters calculated for the earthquake are a length of 30 km, a width of 27 km and a slip of one metre. The NW trending nodal plane of this earthquake coincides with the strike of the NW trending Naqara Fault on the southeast coast of Viti Levu.

Tsunami

The first sign of the tsunami was observed about one minute after the earthquake when a disturbance of the sea surface was noticed by the captain of the cutter ''Adi Tirisa'' "beyond the reef some 4 to 5 miles southwest of Suva…she was badly shaken and a little later three great spouts burst out of the sea, carrying mud, stones, and part of a long-wrecked vessel…" The location of this disturbance was at the western end of the entrance to the Suva Passage.

Origin

From the type of fault displacement and the magnitude of the event it was clear that the tsunami was not caused by any displacement of the seabed associated with the earthquake. The shaking triggered collapse of part of the

barrier reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

at Suva into the Suva Canyon. The current reef edge shows the effects of repeated slope failure. The characteristics of the 1953 landslide scar were investigated using a high resolution multibeam echo sounder. The area immediately offshore from the reef is a composite failure surface, within which a fresh scar was identified with a width of 800 m, defining an estimated slide volume of 60 million cubic metres. Numerical modelling of this as the likely source was able to reproduce many aspects of the observed development of the tsunami.

Damage

This earthquake was the most destructive in Fiji's recorded history, the tremor itself killing three people and seriously injuring twenty others. The most serious damage occurred in the southeastern part of Viti Levu. The tsunami caused particular damage to coastal areas not protected by barrier reefs, devastating the villages of Nakasaleka and Makaluva. There were five deaths from the tsunami, three at Suva and two at Nakasaleka. Had the tsunami occurred at high tide, rather than low tide it would have been more damaging. The landslide that caused the tsunami generated

turbidity current A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in the process. T ...

s that damaged several underwater cables in the Suva Canyon. The total damage caused by earthquake and tsunami was estimated as $500,000 (at 1953 values in

U.S. dollars The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

References

External links

* {{Earthquakes in 1953 1953 earthquakes Earthquakes in Oceania Natural disasters in Fiji 1953 in Fiji 1950s tsunamis Tsunamis in Fiji 1953 disasters in Fiji