On October 31 at 17:53 UTC (November 1 at 03:53

AEST Australia uses three main time zones: Australian Western Standard Time (AWST; UTC+08:00), Australian Central Standard Time (ACST; UTC+09:30), and Australian Eastern Standard Time (AEST; UTC+10:00). Time is regulated by the individual state gov ...

) the island of

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

was shaken by an earthquake of magnitude 6.9 that particularly affected the city of

Madang Madang (old German name: ''Friedrich-Wilhelmshafen'') is the capital of Madang Province and is a town with a population of 27,420 (in 2005) on the north coast of Papua New Guinea. It was first settled by the Germans in the 19th century. Histor ...

on the north coast of

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

. Causing between five and eighteen fatalities, it triggered landslides that ran down steep hills into poorly reinforced wooden huts. The area that experienced the most powerful

intensity Intensity may refer to: In colloquial use *Strength (disambiguation) *Amplitude * Level (disambiguation) * Magnitude (disambiguation) In physical sciences Physics *Intensity (physics), power per unit area (W/m2) *Field strength of electric, ma ...

extended out from the

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 ...

. Underwater landslides caused minor

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 ...

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

Tectonic setting

The island of New Guinea lies within the complex zone of

collision In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word ''collision'' refers to incidents in which two or more objects collide with great fo ...

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 ...

. Within this overall setting, the active tectonics of northern Papua New Guinea is dominate by the effects of continuing collision between the Huon– Finisterre

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 ...

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...

with the edge of the Australian

continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

. The overall shortening is concentrated into two zones of

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

ing, the Ramu–Markham fault zone, which forms the southwestern boundary of the Huon–Finisterre terrane, and the Highlands Thrust Belt, which lies further southwest and deforms the Australian margin. The hanging wall of the Ramu–Markham thrust system is broken up by a series of strike-slip faults. The orientation of these faults, parallel to the direction of thrusting, suggests that they accommodate distortion of the Huon–Finisterre block. Most of the seismicity in northern Papua New Guinea is associated with the Ramu–Markham fault system, with a smaller number of earthquakes occurring on the strike-slip faults and on the Highlands Thrust Belt.

Earthquake

The earthquake took place near

, approximately northwest of

Port Moresby (; Tok Pisin: ''Pot Mosbi''), also referred to as Pom City or simply Moresby, is the capital and largest city of Papua New Guinea. It is one of the largest cities in the southwestern Pacific (along with Jayapura) outside of Australia and New Z ...

. Generally, it was on the northeast coast. The earthquake was the result of

strike-slip faulting In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

Damage and casualties

Up to eighteen deaths and twenty injuries occurred. Felt throughout the entire island of New Guinea, it caused extensive damage in the city of Madang, where it killed three people. Several homes buckled and cracks appeared in streets. On the coast of the island, a cable connecting telephone units for

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...

was cut. 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 . When a canoe was inverted by this change, three people were killed. Its maximum

of VIII (''Severe'') was restricted to a zone from the epicenter (including the epicenter). Up to away from the epicenter, damage measuring intensity VII (''Very strong'') 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 was Madang. Houses with poor

earthquake engineering Earthquake engineering is an interdisciplinary branch of engineering that designs and analyzes structures, such as buildings and bridges, with earthquakes in mind. Its overall goal is to make such structures more resistant to earthquakes. An earth ...

such as those with weakly reinforced frames performed poorly. Forty-five percent of the city's steel water tanks were beyond repair.

References

External links

* {{Earthquakes in Papua New Guinea New Guinea Earthquake, 1970 New Guinea Earthquake, 1970 1970s tsunamis Earthquakes in Papua New Guinea October 1970 events in Oceania 1970 in Papua New Guinea Madang Province 1970 disasters in Papua New Guinea

Tectonic setting

Earthquake

Damage and casualties

See also

References

External links