The 1979 Yapen earthquake occurred on September 12 at 05:17:51 UTC. It had an

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

near the coast of

Yapen Yapen (also Japan, Jobi) is an island of Papua, Indonesia. The Yapen Strait separates Yapen and the Biak Islands to the north. It is in Cenderawasih Bay off the north-western coast of the island of New Guinea. To the west is Mios Num Islan ...

Island in

Irian Jaya New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. Measuring 7.5 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pap ...

and having a depth of , it caused severe damage on the island. At least 115 were killed due to shaking and a moderate

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 exp ...

Tectonic setting

The northern coast of

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

is situated in a region of east–west oblique plate convergence between the Australian and Pacific plates. The oceanic crust of the Pacific Plate subducts obliquely beneath New Guinea and nearby islands along the

New Britain Trench The New Britain Trench (also known as Bougainville-New Britain Trench or New Britain-Solomon Trench) has formed due to subduction of the floor of the Solomon Sea and has some of the highest current seismic activity in the world. The trench wa ...

and Manokwari Trough. A large component of this oblique convergence is accommodated by east–west left-lateral shear at a rate of 80 mm/yr. The shear zone is approximately long and is a complex zone of faults. The

Sorong Sorong is the largest city and the capital of the Indonesian province of Southwest Papua. The city is located on the western tip of the island of New Guinea with its only land borders being with Sorong Regency. It is the gateway to Indonesia' ...

, Koor, Ransiki and Yapen faults are the largest structures forming the shear zone.

Earthquake

The earthquake occurred due to left-lateral strike-slip faulting on the long Yapen Fault. The Yapen Fault is the fastest-slipping fault in the shear zone, estimated to move at a rate of 46 ± 12 mm/yr. It crosses east–west through

Cenderawasih Bay Cenderawasih Bay ( id, Teluk Cenderawasih, "Bird of Paradise Bay"), also known as Sarera Bay ( id, Teluk Sarera) and formerly Geelvink Bay ( nl, Geelvinkbaai), is a large bay in northern Province of Papua, Central Papua and West Papua, New Gui ...

. Seismologist Emile A. Okal estimated that the rupture produced up to of displacement on an east-southeast–west-northwest fault. The total rupture length was × . A study in 2002 estimated the rupture to be × and producing up to of slip. It was followed by an

aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousand ...

sequence trending east–west. A cluster of aftershocks occurred north of the mainshock, at Pandaidori, displayed reverse faulting. This aftershock sequence is thought to be triggered by stress transfer.

Damage

Shaking from the mainshock killed 15 people and demolished at least 1,000 homes. Despite being a strike-slip earthquake, slip of up to was sufficient to generate a moderate tsunami near the coastline. Waves measuring was recorded at

Biak Biak is an island located in Cenderawasih Bay near the northern coast of Papua, an Indonesian province, and is just northwest of New Guinea. Biak is the largest island in its small archipelago, and has many atolls, reefs, and corals. The large ...

. The tsunami killed at least 100 people on Yapen Island. A fisherman on Biak was among the fatalities after being swept away by the waves. In West Yapen District, 76 homes were destroyed and flooded by the tsunami. Many residents had to hold themselves onto stable objects during the shaking. Ground cracks occurred. Many churches and homes collapsed. In two villages, all homes were destroyed. A large

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

up to was reported in Serui. In Menawi, 254 homes were seriously damaged. A further 90 homes and a school were destroyed at Randawaya II. After the earthquake, local government officials in

Jayapura Jayapura (formerly Dutch: ''Hollandia'') is the capital and largest city of the Indonesian province of Papua. It is situated on the northern coast of New Guinea island and covers an area of . The city borders the Pacific Ocean and Yos Sud ...

were not notified about the earthquake due to a local event. It was only after news was transmitted to

Garuda Indonesia Garuda Indonesia is the flag carrier of Indonesia, headquartered at Soekarno–Hatta International Airport. A successor of KLM Interinsulair Bedrijf, it is a member of SkyTeam and the second-largest airline of Indonesia after Lion Air, ope ...

in Sentani were they informed. The Indonesian Minister of Home Affairs appointed the Governor of Irian Jaya to respond immediately to the affected area. A total of 16,500 residents were displaced.

References

External links

* {{Earthquakes in Indonesia 1979 earthquakes

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 ...

Yapen Islands Tsunamis in Indonesia 1979 in Indonesia Papua (province) Schouten Islands Western New Guinea 1979 tsunamis

Tectonic setting

Earthquake

Damage

See also

References

External links