1987 Edgecumbe earthquake
| 1987 Edgecumbe earthquake | |||
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| Coordinates | 37 ° 52 '48 " S , 176 ° 50' 24" O | ||
| date | March 2nd 1987 | ||
| Time | 1:42 p.m. local time | ||
| intensity | 9 on the MM scale | ||
| Magnitude | 6.5 M W | ||
| depth | 6 km | ||
| epicenter | between Thornton and Matata
(15 km north of Edgecumbe)
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| country | New Zealand | ||
| Affected places |
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| Tsunami | No | ||
| dead | 0 | ||
| Injured | 25th | ||
| damage | NZ $ 315 million | ||
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The 1987 Edgecumbe earthquake in the Bay of Plenty region of New Zealand was one of the most expensive earthquakes New Zealand has experienced up to that point, despite its comparatively low magnitude of 6.5 M W for this region .
geography
The epicenter of the quake was in the Rangitaiki Plains formed by the Rangitaiki River between the small towns of Thornton and Matata , just under 15 km northwest of Edgecumbe on the Tarawera River and thus very close to the coast of the Bay of Plenty .
The quake
On March 2, 1987, around 1:35 p.m., an earthquake with a magnitude of 5.2 M L (other sources name 4.9) shook the Bay of Plenty with minor announcements . The power went out and the residents left their homes. Only 7 minutes later, the second quake followed with a strength of 6.5 M W (other sources name 6.3) and broke the earth's surface in various places, southwest of Edgecumbe over a length of 7 km, creating an offset of up to to 3 m and caused the northwestern part of the plain to drop abruptly to 2 m. The resulting trench was up to 3 m deep. In addition to the fractures and subsidence, soil liquefaction was observed near the town of Te Teko and a field with old tree stumps that were still standing came to light in part of the river bed of the Rangitaiki River.
In the six hours following the main shock wave, four more aftershocks with a magnitude of more than five followed. Although the magnitude of the quake was not extremely high compared to other earthquakes in the country, considerable damage was caused by the shocks running flat under the surface, which observers described as rolling , caused. Edgecumbe, Kawerau, Te Teko, Thornton and Matata were the cities hardest hit.
In Edgecumbe around 50% of the houses were damaged. Roads broke open and became impassable. The rails of the railway line were bent to the side, so badly in some places that an 80-ton locomotive was lifted from the tracks and thrown on its side.
The industrial sector was also hit hard. The paper mill in Kawerau , 18 km southwest of Edgecumbe as an example, was just as badly damaged as the dairy plant in Edgecumbe, where transformers, milk tanks and the factory building were completely destroyed.
The Matahina Dam , 15 km south of Edgecumbe, was also affected. The situation was so serious that the reservoir had to be emptied and 3,000 people had to be temporarily evacuated. As a result of the quake, the dam had cracked and the supporting pillars had leaked. The repair was carried out in 1988, but the dam had to be strengthened in the late 1990s in order to cope with future stronger earthquakes.
Forewarned by the foreshock, no people were killed in the main quake, but there were 25 registered injuries. After the damage was initially estimated at NZ $ 400 million , the insurance companies put the regulated damage at NZ $ 315 million. The actual costs will have been higher.
See also
literature
- Rebecca Ansell, John Taber : Caught in the Crunch - Earthquakes and Volcanoes in New Zealand . Harper Collins Publishers (NZ) Ltd. , Auckland 1996, ISBN 1-86950-201-9 (English).
- Quentin Ruscoe : Walking on Jelly - The Bay of Plenty Earthquake 1987 . DSIR Publishing , Wellington 1988, ISBN 0-477-02526-9 (English).
Web links
- M 6.5, Edgecumbe, March 2, 1987 . GeoNet - GNS Science ,accessed April 7, 2013.
- Story: Historic earthquakes - The 1987 Edgecumbe earthquake . Te Ara - The Encyclopedia of New Zealand,accessed March 5, 2010.
Individual evidence
- ↑ a b M 6.5, Edgecumbe, 2 March 1987 . GeoNet - GNS Science , accessed April 7, 2013 .
- ^ A b Story: Historic earthquakes - The 1987 Edgecumbe earthquake . Te Ara - The Encyclopedia of New Zealand , accessed March 5, 2010 .
- ^ Fault rupture, 1987 Edgecumbe earthquake . Te Ara - The Encyclopedia of New Zealand , accessed April 7, 2013 (photograph of the fault).
- ^ The Edgecumbe Fault (2nd of 2) . Te Ara - The Encyclopedia of New Zealand , accessed April 7, 2013 (photograph of the fault).
- ^ Edgecumbe Earthquake, Twenty Years On . GeoNet - GNS Science , February 27, 2007, archived from the original on November 23, 2010 ; accessed on April 7, 2013 (English, original website no longer available).
- ↑ a b New Zealand Disaster - Edgecumbe Earthquake . Christchurch Library , accessed March 5, 2010 .
- ^ Life on the Edge - New Zealand's Natural Hazards and Disasters . David Bateman Ltd. , Auckland 2007, ISBN 978-1-86953-690-9 (English).
- ^ 1.19 Matahina Hydro Dam Seismic Hazard Assessment - New Zealand . Earthquake Engineering New Zealand , archived from the original on May 13, 2010 ; accessed on March 5, 2010 (English, original website no longer available).
- ↑ Ruscoe : Walking on Jelly - The Bay of Plenty Earthquake 1987 . 1988, p. 6 (English).
- ↑ Inangahua Quake left $ 39 Million Insurance Bill . GNS Science , May 24, 1998, archived from the original on June 5, 2010 ; accessed on April 7, 2013 (English, original website no longer available).