2009 Fiordland earthquake
Encyclopedia
The 2009 Fiordland earthquake was a magnitude 7.8 earthquake
that struck the South Island
of New Zealand
at 9:22 pm (NZST) on 15 July 2009. The earthquake was centred in the remote region of Fiordland
, with the epicentre located 150 km (93.2 mi) west-north-west of Invercargill
near Dusky Sound
in Fiordland National Park
, at a depth of 12 km (7.5 mi). It is the largest New Zealand earthquake since the 1931 Hawke's Bay earthquake
, which also had a magnitude of 7.8.
subducting
beneath the Pacific Plate
. The earthquake lifted a large area of land around the epicenter approximately 1 metre.
New Zealand's Institute of Geological and Nuclear Sciences (GNS Science) initially measured the earthquake at magnitude 6.6, but later revised the magnitude to 7.8.
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".
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
10 cm. It is also believed to have caused an increased stress in the southern, offshore part of the Alpine Fault
.
as far as New Plymouth
. No injuries or fatalities were reported, and it caused only minor damage. Power outages were experienced in several parts of the South Island. Over 200 claims for damage have been listed with the Earthquake Commission
, New Zealand's agency for earthquake compensation, with more expected.
Landslides in the Fiordland National Park
near Dusky Sound
cleared large tracts of forest.
warnings were issued soon after the earthquake by authorities in New Zealand and Australia
, as well as the Pacific Tsunami Warning Center
in Hawaii
. Civil defence officials in Southland
also issued a 'potential tsunami' warning, stating their concerns about widely varying measurements of the earthquake. 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. In the event, waves were recorded along New Zealand's western coastline, with a meter at Jackson Bay, Haast
, measuring the wave at one metre, peak to trough. (An amplitude of 17 cm) The tsunami warnings were subsequently cancelled or reduced.
Wednesday, 15 July at 9:41 pm, magnitude 6.1
Thursday, 16 July at 1:50 am, magnitude 5.9
Thursday, 16 July at 11:41 am, magnitude 5.1
Thursday, 16 July at 12:24 pm, magnitude 5.3
Thursday, 16 July at 12:44 pm, magnitude 5.5
Thursday, 16 July at 2:13 pm, magnitude 5.1
Thursday, 16 July at 6:30 pm, magnitude 5.6
Thursday, 16 July at 9:36 pm, magnitude 4.4
Friday, 17 July at 4:13 am, magnitude 5.3
Friday, 17 July at 5:27 am, magnitude 5.6
Friday, 17 July at 10:18 am, magnitude 5.5
Friday, 17 July at 11:01 am, magnitude 5.2
Friday, 17 July at 6:39 pm, magnitude 5.6
Saturday, 18 July at 4:40 am, magnitude 5.1
Saturday, 18 July at 8:25 am, magnitude 4.5
Saturday, 18 July at 12:57 am, magnitude 4.9
Sunday, 19 July at 3:33 am, magnitude 5.4
Sunday, 19 July at 5:11 pm, magnitude 5.5
Sunday, 19 July at 8:48 pm, magnitude 5.2
Monday, 20 July at 7:04 pm, magnitude 4.5
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
that struck the South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
at 9:22 pm (NZST) on 15 July 2009. The earthquake was centred in the remote region of Fiordland
Fiordland
Fiordland is a geographic region of New Zealand that is situated on the south-western corner of the South Island, comprising the western-most third of Southland. Most of Fiordland is dominated by the steep sides of the snow-capped Southern Alps, deep lakes and its ocean-flooded, steep western valleys...
, with the epicentre located 150 km (93.2 mi) west-north-west of Invercargill
Invercargill
Invercargill is the southernmost and westernmost city in New Zealand, and one of the southernmost cities in the world. It is the commercial centre of the Southland region. It lies in the heart of the wide expanse of the Southland Plains on the Oreti or New River some 18 km north of Bluff,...
near Dusky Sound
Dusky Sound
Dusky Sound is a fiord on the south west corner of New Zealand, in Fiordland National Park.-Geography:One of the most complex of the many fjords on this coast, it is also one of the largest, 40 kilometres in length and eight kilometres wide at its widest point...
in Fiordland National Park
Fiordland National Park
Fiordland National Park occupies the southwest corner of the South Island of New Zealand. It is the largest of the 14 national parks in New Zealand, with an area of 12,500 km², and a major part of the Te Wahipounamu World Heritage site...
, at a depth of 12 km (7.5 mi). It is the largest New Zealand earthquake since the 1931 Hawke's Bay earthquake
1931 Hawke's Bay earthquake
The 1931 Hawke's Bay earthquake, also known as the Napier earthquake, occurred in New Zealand at 10:47 am on Tuesday 3 February 1931, killing 256 and devastating the Hawke's Bay region. It remains New Zealand's deadliest natural disaster...
, which also had a magnitude of 7.8.
Magnitude and earth movement
The main shock was a reverse fault (thrust), with the Indo-Australian PlateIndo-Australian Plate
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters...
subducting
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
beneath the Pacific Plate
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....
. The earthquake lifted a large area of land around the epicenter approximately 1 metre.
New Zealand's Institute of Geological and Nuclear Sciences (GNS Science) initially measured the earthquake at magnitude 6.6, but later revised the magnitude to 7.8.
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".
The quake twisted New Zealand's South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
, with Puysegur Point, on the Southwestern tip of the island, moving 30 cm closer to Australia (westward); Te Anau
Te Anau
Te Anau is a town in the South Island of New Zealand. It is on the eastern shore of Lake Te Anau in Fiordland. Lake Te Anau is the largest lake in the South Island and second only within New Zealand to Lake Taupo. The 2001 census recorded the town's population as 1,857...
moved 10 cm, Bluff
Bluff, New Zealand
Bluff is a town and seaport in the Southland region, on the southern coast of the South Island of New Zealand. It is the southern-most town in New Zealand and, despite Slope Point being further to the south, is colloquially used to refer to the southern extremity of the country...
3 cm and Dunedin
Dunedin
Dunedin is the second-largest city in the South Island of New Zealand, and the principal city of the Otago Region. It is considered to be one of the four main urban centres of New Zealand for historic, cultural, and geographic reasons. Dunedin was the largest city by territorial land area until...
10 cm. It is also believed to have caused an increased stress in the southern, offshore part of the Alpine Fault
Alpine Fault
The Alpine Fault is a geological fault, more specifically known as a right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. Earthquakes along the fault, and the...
.
Effects
The earthquake was felt throughout the South Island, and in the lower North IslandNorth Island
The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...
as far as New Plymouth
New Plymouth
New Plymouth is the major city of the Taranaki Region on the west coast of the North Island of New Zealand. It is named after Plymouth, Devon, England, from where the first English settlers migrated....
. No injuries or fatalities were reported, and it caused only minor damage. Power outages were experienced in several parts of the South Island. Over 200 claims for damage have been listed with the Earthquake Commission
Earthquake Commission
The Earthquake Commission provides primary natural disaster insurance to the owners of residential properties in New Zealand. The Government-owned Crown entity manages assets of $5.93 billion NZD...
, New Zealand's agency for earthquake compensation, with more expected.
Landslides in the Fiordland National Park
Fiordland National Park
Fiordland National Park occupies the southwest corner of the South Island of New Zealand. It is the largest of the 14 national parks in New Zealand, with an area of 12,500 km², and a major part of the Te Wahipounamu World Heritage site...
near Dusky Sound
Dusky Sound
Dusky Sound is a fiord on the south west corner of New Zealand, in Fiordland National Park.-Geography:One of the most complex of the many fjords on this coast, it is also one of the largest, 40 kilometres in length and eight kilometres wide at its widest point...
cleared large tracts of forest.
Tsunami
TsunamiTsunami
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...
warnings were issued soon after the earthquake by authorities in New Zealand and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, as well as the Pacific Tsunami Warning Center
Pacific Tsunami Warning Center
The Pacific Tsunami Warning Center is one of two tsunami warning centers that are operated by NOAA in the United States. Headquartered in Ewa Beach, Hawaii, the PTWC is part of an international tsunami warning system program and serves as the operational center for TWS of the Pacific issuing...
in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
. Civil defence officials in Southland
Southland Region
Southland is New Zealand's southernmost region and is also a district within that region. It consists mainly of the southwestern portion of the South Island and Stewart Island / Rakiura...
also issued a 'potential tsunami' warning, stating their concerns about widely varying measurements of the earthquake. Reacting to the Pacific warnings, about fifty residents and tourists on Lord Howe Island
Lord Howe Island
Lord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...
were evacuated, and in Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
a theatre in Bondi Beach was evacuated, and residents told to keep away from the shore. In the event, waves were recorded along New Zealand's western coastline, with a meter at Jackson Bay, Haast
Haast, New Zealand
Haast is an area in the Westland District territorial authority on the west coast of New Zealand's South Island. The Haast region covers over ....
, measuring the wave at one metre, peak to trough. (An amplitude of 17 cm) The tsunami warnings were subsequently cancelled or reduced.
Aftershocks
Primary aftershocks to dateWednesday, 15 July at 9:41 pm, magnitude 6.1
Thursday, 16 July at 1:50 am, magnitude 5.9
Thursday, 16 July at 11:41 am, magnitude 5.1
Thursday, 16 July at 12:24 pm, magnitude 5.3
Thursday, 16 July at 12:44 pm, magnitude 5.5
Thursday, 16 July at 2:13 pm, magnitude 5.1
Thursday, 16 July at 6:30 pm, magnitude 5.6
Thursday, 16 July at 9:36 pm, magnitude 4.4
Friday, 17 July at 4:13 am, magnitude 5.3
Friday, 17 July at 5:27 am, magnitude 5.6
Friday, 17 July at 10:18 am, magnitude 5.5
Friday, 17 July at 11:01 am, magnitude 5.2
Friday, 17 July at 6:39 pm, magnitude 5.6
Saturday, 18 July at 4:40 am, magnitude 5.1
Saturday, 18 July at 8:25 am, magnitude 4.5
Saturday, 18 July at 12:57 am, magnitude 4.9
Sunday, 19 July at 3:33 am, magnitude 5.4
Sunday, 19 July at 5:11 pm, magnitude 5.5
Sunday, 19 July at 8:48 pm, magnitude 5.2
Monday, 20 July at 7:04 pm, magnitude 4.5