2009 Fiordland earthquake

The 2009 Fiordland earthquake struck the South Island of New Zealand with a magnitude of 7.8 [1] at 9:22 pm (NZST) on 15 July. The earthquake was centred in the remote region of Fiordland, with the epicentre located 150 km (93 mi) west-north-west of Invercargill near Dusky Sound in Fiordland National Park, at a depth of 12 km (7.5 mi).[1][2] It is among the largest New Zealand earthquakes to occur, including the Culverden/Kaikoura earthquake in 2016 and the 1931 Hawke's Bay earthquake, which both had a magnitude of 7.8.[3][4]

2009 Fiordland earthquake
2009 New Zealand earthquake
UTC time2009-07-15 09:22:29
ISC event15157724
USGS-ANSSComCat
Local date15 July 2009
Local time9:22 pm (NZST)
Magnitude7.8 Mw
Depth12 kilometres (7 mi)
Epicenter45°43′16″S 166°38′35″E / 45.721°S 166.643°ECoordinates: 45°43′16″S 166°38′35″E / 45.721°S 166.643°E
Areas affectedNew Zealand
Tsunami17 cm (6.7 in)
Aftershocks>100
Casualties0

Earthquake

The main shock was a reverse fault (thrust), with the Indo-Australian Plate subducting beneath the Pacific Plate.[3] The earthquake lifted a large area of land around the epicenter approximately 1 metre.[5]

New Zealand's Institute of Geological and Nuclear Sciences (GNS Science) initially measured the earthquake at magnitude 6.6,[6] but later revised the magnitude to 7.8.[7]

The reported energy release was compared to "500 million tonnes of TNT,[and] 25,000 times more powerful than the atomic bomb dropped on Nagasaki in 1945".[8]

The quake twisted New Zealand's South Island, with Puysegur Point, on the Southwestern tip of the island, moving 30 cm closer to Australia (westward); Te Anau moved 10 cm, Bluff 3 cm and Dunedin 1 cm. It is also believed to have caused an increased stress in the southern, offshore part of the Alpine Fault.[9]

A considerable number of aftershocks were recorded.

Effects

NASA fiordland 2009 earthquake
NASA map showing epicentre of earthquake and its aftershocks

The earthquake was felt throughout the South Island, and in the lower North Island as far as New Plymouth. No injuries or fatalities were reported, and it caused only minor damage.[7] Power outages were experienced in several parts of the South Island.[10][11] Over 200 claims for damage have been listed with the Earthquake Commission, New Zealand's agency for earthquake compensation.[8]

Landslides in the Fiordland National Park near Dusky Sound cleared large tracts of forest.[8]

Tsunami

Tsunami warnings were issued soon after the earthquake by authorities in New Zealand and Australia, as well as the Pacific Tsunami Warning Center in Hawaii.[12] Civil defence officials in Southland also issued a 'potential tsunami' warning, stating their concerns about widely varying measurements of the earthquake.[10] Reacting to the Pacific warnings, about fifty residents and tourists on Lord Howe Island were evacuated, and in Sydney a theatre in Bondi Beach was evacuated, and residents told to keep away from the shore.[13] In the event, waves recorded along New Zealand's western coastline measured at one metre, peak to trough, in the Haast area.[3] (An amplitude of 17 cm)[14] The tsunami warnings were subsequently cancelled or reduced.[7]

See also

References

  1. ^ a b "Magnitude 7.8 - OFF WEST COAST OF THE SOUTH ISLAND, N.Z." USGS. 15 July 2009. Archived from the original on 12 August 2009. Retrieved 15 July 2009.
  2. ^ "New Zealand Earthquake Report - Jul 15 2009 at 9:22 pm (NZST)". GeoNet. 15 July 2009. Archived from the original on 18 July 2009. Retrieved 16 July 2009.
  3. ^ a b c "Fiordland quake biggest for 80 years". GeoNet. Institute of Geological and Nuclear Sciences. 16 July 2009. Archived from the original on 26 July 2009. Retrieved 21 July 2009.
  4. ^ NZPA (19 July 2009). "Weaker, more frequent Fiordland aftershocks". Stuff.co.nz. Archived from the original on 26 July 2009. Retrieved 2009-07-21.
  5. ^ "Ground raised one metre by quake". Radio New Zealand. 18 July 2009. Archived from the original on 26 July 2009. Retrieved 2009-07-21.
  6. ^ "Tsunami alert after NZ earthquake". BBC News. 15 July 2009. Retrieved 15 July 2009.
  7. ^ a b c NZPA, Fairfax (15 July 2009). "Fiordland quake measures 7.8". stuff.co.nz. Retrieved 15 July 2009.
  8. ^ a b c Yvonne Tahana (17 July 2009). "After-shocks continue in Southland". New Zealand Herald. Archived from the original on 26 July 2009. Retrieved 21 July 2009.
  9. ^ Paul Gormon (22 July 2009). "Our Australian cousins just got closer". The Press. Fairfax Media. Archived from the original on 26 July 2009. Retrieved 2009-07-21.
  10. ^ a b Dye, Stuart; NZPA (15 July 2009). "South Island quake prompts 'potential tsunami' warning". The New Zealand Herald. Retrieved 15 July 2009.
  11. ^ "Quake strikes off New Zealand's Southland". Xinhua. 15 July 2009. Retrieved 15 July 2009.
  12. ^ Beckford, Gyles (15 July 2009). "New Zealand quake sparks tsunami warnings". Reuters. Retrieved 15 July 2009.
  13. ^ "Fiordland quake causes evacuation in Sydney". Television New Zealand News. 16 July 2009. Archived from the original on 26 July 2009. Retrieved 2009-07-21.
  14. ^ "Tsunami Information Statement". West Coast and Alaska Tsunami Warning Center. 15 July 2009. Archived from the original on 26 July 2009. Retrieved 21 July 2009.

Further reading

  • Rogers, Anna (2013) [1996]. The Shaky Isles: New Zealand Earthquakes (2 ed.). Wellington: Grantham House. pp. 185, 186. ISBN 978-1-86934-119-0.
  • Wright, Matthew (2014). Living on shaky ground: The science and story behind New Zealand's earthquakes. Auckland: Random House (New Zealand). pp. 174, 175. ISBN 978-1-77553-688-8.

External links

2009 in New Zealand

The following lists events that happened during 2009 in New Zealand.

List of 21st-century earthquakes

The following is a list of significant earthquakes during the 21st century, listing earthquakes of magnitude 7 and above, or which caused fatalities. Deaths due to earthquake-caused tsunamis are included. In terms of fatalities, the 2010 Haiti earthquake was the most destructive event, followed by the 2004 Indian Ocean earthquake, 2005 Pakistan earthquake and 2008 Sichuan earthquake.

List of earthquakes in New Zealand

This is a list of large earthquakes that have occurred in New Zealand. Only earthquakes with a magnitude of 6.0 or greater are listed, except for a few that had a moderate impact. Aftershocks are not included, unless they were of great significance or contributed to a death toll, such as the M 6.3 2011 Christchurch earthquake and the M 7.3 aftershock to the 1931 Hawke's Bay earthquake.

Earthquakes occur frequently in New Zealand as the country is situated in the collision zone between the Indo-Australian and Pacific tectonic plates, part of the Pacific Basin Ring of Fire, where many earthquakes and volcanoes occur. Most events occur along the main ranges running from Fiordland in the southwest to East Cape in the northeast. This axis follows the boundary between the Indo-Australian and Pacific plates. Large earthquakes are less common along the central Alpine Fault, where the plates are not subducting and the forces are accommodated in different ways.

The largest city within the highest-risk zone is the nation's capital, Wellington, followed by Hastings then Napier. All these cities have experienced severe earthquakes since European settlement. About 14,000 earthquakes occur in and around the country each year, of which between 150 and 200 are big enough to be felt. As a result, New Zealand has very stringent building regulations.

Quite early on, European settlers were faced with the reality of earthquakes in their new home. On 26 May 1840, the new settlement at Port Nicholson was struck by the first of a number of earthquakes and tremors. Early settlers learned fairly quickly the importance of using appropriate building methods in an earthquake-prone country. The 1848 earthquake, centred in Marlborough, caused great damage to the brick and masonry buildings in Wellington, and the city was rebuilt mainly in wood; consequently it suffered comparatively little damage in the 8.2 magnitude earthquake of 1855, which lifted the land 2–3m. Many buildings in Hastings and Napier were damaged in the 1931 Hawke's Bay earthquake. New building regulations meant that any new buildings constructed afterwards attempted to take earthquake shaking into account in building design.

Tuatapere

Tuatapere is a small rural town in Southland, New Zealand. It is located eight kilometres from the southern coast. The Waiau River flows through the town before reaching Te Waewae Bay, where it has its outflow into Foveaux Strait. The main local industries are forestry and farming. As of the 2013 New Zealand census, its population is 558.Tuatapere has a logging museum and is located on the Southern Scenic Route from Invercargill to Te Anau making it a well-travelled tourist stop. The Clifden Suspension Bridge and Clifden War Memorial are located near State Highway 96 outside Tuatapere.

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