1855 Wairarapa earthquake
Encyclopedia
The 1855 Wairarapa earthquake occurred on 23 January at about 9 p.m. In Wellington
, close to the epicenter
, shaking lasted for at least 50 seconds. The magnitude
of the earthquake is estimated to have been in the range 8.1-8.3, the most powerful recorded in New Zealand
since systematic European colonisation began in 1840. This earthquake
was associated with the largest observed movement on a strike-slip fault, maximum 18 metres. It has been suggested that the surface rupture formed by this event helped influence Charles Lyell
to link earthquakes with rapid movement on faults.
and Pacific Plate
s. In the South Island
most of the relative displacement between these plates is taken up along a single dextral (right lateral) strike-slip fault with a major reverse component, the Alpine Fault
. In the North Island
the displacement is mainly taken up along the Kermadec subduction zone
, although the remaining dextral strike-slip component of the relative plate motion is accommodated by the North Island Fault System
(NIFS). A group of dextral strike-slip structures, known as the Marlborough Fault System
, transfer displacement between the mainly transform
and convergent type plate boundaries
in a complex zone at the northern end of the South Island. The earthquake occurred on the Wairarapa Fault
which is part of the NIFS.
on the northwestern side of the fault with vertical offsets of about 6 metres near the fault reducing to almost nothing on the western coast of the Wellington Peninsula. The estimated magnitude of about 8.2 is unusually large for an earthquake associated with movement on a mainly strike-slip fault, and the coseismic offset would have been the largest known for such an event. It has been suggested that this was caused by the rupture propagating down to where the fault links through to the top of the subducting Pacific Plate. Geomorphological
evidence, particularly the uplifted beach ridges observed at Turakirae Head, appears to record three previous coseismic uplifts of the Rimutaka Range caused by earthquakes similar in magnitude to the 1855 event, with a recurrence interval of about 2200 years.
using mainly wooden structures; only one person was known to have died. In the surrounding countryside at least another four people (possibly as many as eight) were reported to have died during the earthquake. Numerous landslides were reported along the slopes of the Rimutaka Range.
The uplift of the northwestern side of Wellington Bay rendered many of the jetties in the harbour unusable, although this new area of land provided an excellent new rail and road route to the north.
generated New Zealand’s largest historical locally-generated tsunami
.
New Zealand's National Institute of Water and Atmospheric Research
created an animated tsunami simulation model based on the 1855 Wairarapa event, which was screened on the television tele-drama "Aftershock"
Wellington
Wellington is the capital city and third most populous urban area of New Zealand, although it is likely to have surpassed Christchurch due to the exodus following the Canterbury Earthquake. It is at the southwestern tip of the North Island, between Cook Strait and the Rimutaka Range...
, close to 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...
, shaking lasted for at least 50 seconds. The magnitude
Seismic scale
A seismic scale is used to calculate and compare the severity of earthquakes....
of the earthquake is estimated to have been in the range 8.1-8.3, the most powerful recorded in 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...
since systematic European colonisation began in 1840. This earthquake
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...
was associated with the largest observed movement on a strike-slip fault, maximum 18 metres. It has been suggested that the surface rupture formed by this event helped influence Charles Lyell
Charles Lyell
Sir Charles Lyell, 1st Baronet, Kt FRS was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by slow-moving forces still in operation...
to link earthquakes with rapid movement on faults.
Tectonic setting
New Zealand lies along the boundary between the AustralianIndo-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...
and 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....
s. In 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...
most of the relative displacement between these plates is taken up along a single dextral (right lateral) strike-slip fault with a major reverse component, 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...
. In the North Island
North 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...
the displacement is mainly taken up along the Kermadec subduction zone
Kermadec Trench
The Kermadec trench is one of Earth's deepest oceanic trenches, reaching a depth of . Formed by the subduction of the Pacific Plate under the Indo-Australian Plate, it runs over a thousand kilometres parallel with and to the east of the Kermadec Ridge and island arc, from near the northeastern tip...
, although the remaining dextral strike-slip component of the relative plate motion is accommodated by the North Island Fault System
North Island Fault System
The North Island Fault System or North Island Dextral Fault Belt is a set of southwest-northeast trending seismically-active faults in the North Island of New Zealand that carry most of the dextral strike-slip component of the oblique convergence of the Pacific Plate with the Australian Plate...
(NIFS). A group of dextral strike-slip structures, known as the Marlborough Fault System
Marlborough Fault System
The Marlborough Fault System is a set of four large dextral strike-slip faults and other related structures in the northern part of South Island, New Zealand, which transfer displacement between the mainly transform plate boundary of the Alpine fault and the mainly destructive boundary of the...
, transfer displacement between the mainly transform
Transform fault
A transform fault or transform boundary, also known as conservative plate boundary since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction. Furthermore, transform faults end abruptly...
and convergent type plate boundaries
Convergent boundary
In plate tectonics, a convergent boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide...
in a complex zone at the northern end of the South Island. The earthquake occurred on the Wairarapa Fault
Wairarapa Fault
The Wairarapa Fault is an active seismic fault in the southern part of the North Island of New Zealand. It is a dextral strike-slip fault with a component of uplift to the northwest as expressed by the Rimutaka Range...
which is part of the NIFS.
Earthquake characteristics
The earthquake was associated with the rupturing of approximately 150 km of the Wairarapa Fault. A horizontal displacement of up to 18 metres was accompanied by uplift and tilting of the Rimutaka RangeRimutaka Range
The Rimutaka Range is one of several mountain ranges in the North Island of New Zealand which form a ridge running parallel with the east coast of the island between East Cape and Wellington.The ridge is at its most pronounced in the southern part of the island, where it consists of the Ruahine,...
on the northwestern side of the fault with vertical offsets of about 6 metres near the fault reducing to almost nothing on the western coast of the Wellington Peninsula. The estimated magnitude of about 8.2 is unusually large for an earthquake associated with movement on a mainly strike-slip fault, and the coseismic offset would have been the largest known for such an event. It has been suggested that this was caused by the rupture propagating down to where the fault links through to the top of the subducting Pacific Plate. Geomorphological
Geomorphology
Geomorphology is the scientific study of landforms and the processes that shape them...
evidence, particularly the uplifted beach ridges observed at Turakirae Head, appears to record three previous coseismic uplifts of the Rimutaka Range caused by earthquakes similar in magnitude to the 1855 event, with a recurrence interval of about 2200 years.
Damage
Wellington experienced severe shaking but the resulting damage was reduced as the city had been extensively rebuilt following the 1848 Marlborough earthquake1848 Marlborough earthquake
The 1848 Marlborough earthquake is the name associated with a severe earthquake which occurred at 1:40 a.m. on 16 October 1848 and whose epicenter was in the Marlborough region of the South Island of New Zealand....
using mainly wooden structures; only one person was known to have died. In the surrounding countryside at least another four people (possibly as many as eight) were reported to have died during the earthquake. Numerous landslides were reported along the slopes of the Rimutaka Range.
The uplift of the northwestern side of Wellington Bay rendered many of the jetties in the harbour unusable, although this new area of land provided an excellent new rail and road route to the north.
Tsunami
The earthquakeEarthquake
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...
generated New Zealand’s largest historical locally-generated 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...
.
New Zealand's National Institute of Water and Atmospheric Research
National Institute of Water and Atmospheric Research
The National Institute of Water and Atmospheric Research or NIWA , is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts commercial and non-commercial research across a broad range of disciplines in the environmental sciences...
created an animated tsunami simulation model based on the 1855 Wairarapa event, which was screened on the television tele-drama "Aftershock"
See also
- List of New Zealand earthquakes
- 1843 Wanganui earthquake1843 Wanganui earthquakeThe 1843 Wanganui earthquake occurred on July 8, 1843 with an epicenter near Wanganui, North Island New Zealand. This was the first earthquake in New Zealand over magnitude 7 for which written records exist.-Tectonic setting:...
- 1888 North Canterbury earthquake1888 North Canterbury earthquakeThe 1888 North Canterbury earthquake is the name associated with a severe earthquake which occurred at 4.10 a.m on 1 September 1888 following a sequence of foreshocks that started the previous evening, and whose epicentre was in the North Canterbury region of the South Island of New Zealand.In...
- Marine terraceMarine terraceA marine terrace, coastal terrace, raised beach or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, mostly an old abrasion platform which has been lifted out of the sphere of wave activity . Thus it lies above or under the current sea level, depending...