The 1970 New Guinea earthquake struck the eponymous island

New Guinea

New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and shocked the city of Madang

Madang

Madang is the capital of Madang Province and is a town with a population of 27,420 on the north coast of Papua New Guinea. It was first settled by the Germans in the 19th century....

 on October 31. Causing between five and fifteen fatalities, it rocked the island and sent landslides cascading down steep hills into poorly reinforced wooden huts. The area that experienced the most powerful intensity extended 20 kilometres (12 mi) out from the epicenter

Epicenter

The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...

. Underwater landslides triggered by the earthquake caused minor 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...

 over about 100 km of coast and severed underwater cables in several places.

Geography and geology

The earthquake took place near Madang

Madang

Madang is the capital of Madang Province and is a town with a population of 27,420 on the north coast of Papua New Guinea. It was first settled by the Germans in the 19th century....

, approximately 350 miles (563 km) northwest of Port Moresby

Port Moresby

Port Moresby , or Pot Mosbi in Tok Pisin, is the capital and largest city of Papua New Guinea . It is located on the shores of the Gulf of Papua, on the southeastern coast of the island of New Guinea, which made it a prime objective for conquest by the Imperial Japanese forces during 1942–43...

. Generally, it was on the northeast coast. The earthquake is thought to have been a result of strike-slip faulting in the area of complex structure along the boundary between the Pacific

Pacific Plate

The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

 and Australian Plates.

Registering a Richter scale magnitude of 7.0, the earthquake took place at 7:53 A.M. HST. Ray Sundean, the director of the Tsunami Warning Center in the area, cited the area as "one having frequent earthquaks."

Damage and casualties

The earthquake resulted in five direct fatalities (up to fifteen) and ten to twenty injuries. Felt throughout the entire island of New Guinea, it caused extensive damage in the city of Madang, where it killed three people. As a result of the earthquake, several homes buckled and cracks appeared in streets. On the coast of the island, the earthquake cut off a cable connecting telephone units for Australia and Guam. Initially officials were worried of a tsunami risk though the earthquake did not produce any. This was due to a dramatic recession of water levels near the epicenter, followed by a rise that at one point measured 3 metres (10 ft). When a canoe was inverted by this change, three people were killed.

Its maximum intensity of 8 was restricted to a zone 20 kilometres (12 mi) from the epicenter (including the epicenter). Up to 70 kilometres (43 mi) away from the epicenter, damage measuring intensity 7 was recorded. Landslides caused most of the deaths (which the Catalog of Tsunamis in the Pacific, 1969-1982 lists as 15), which occurred in wooden huts damaged by the shock and crushed by rock. The number of huts damaged totaled more than 800. The city most damaged by the earthquake was Madang. Houses with poor earthquake engineering

Earthquake engineering

Earthquake engineering is the scientific field concerned with protecting society, the natural and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels...

such as those with weakly reinforced frames performed poorly in the earthquake. 45 percent of the city's steel water tanks were beyond repair.