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| Formation | 2001 |
|---|---|
| Founder | |
| Website | geonet |
GeoNet is a New Zealand natural hazards monitoring system that monitors earthquakes, large landslides, volcanoes, tsunami, and movement of land. Earthquakes and other natural hazards are automatically listed on the GeoNet website and app, and app users are given notifications to be warned about natural hazards. GeoNet was founded in 2001 by GNS Science, the Earthquake Commission and Land Information New Zealand.
GeoNet monitors earthquakes, large landslides, volcanoes, tsunami, and movement of land. [1] [2] This monitoring is done using over 1,000 instruments across the country, [1] with data being transmitted from its sensors to GNS Science's computers in Wellington and Wairākei. On average, the monitoring system detects over 20,000 earthquakes per year. Detected earthquakes that pass a certain threshold are automatically listed on the GeoNet website. [2] GeoNet also forecasts earthquake aftershocks for major earthquakes, such as the 2016 Kaikōura earthquake. [3]
The GeoNet app sends notifications about natural hazards to its users. An example of this is the 2016 Kaikōura earthquake, where the app had sent a total of over 109 million notifications within two days. [4] GeoNet also posts about natural hazards on their social media pages, which are followed by over 200,000 people. [5]
GeoNet was founded in 2001 by GNS Science, the Earthquake Commission and Land Information New Zealand. [1] [5] [4] GeoNet was "relatively [obscure]" until the 2010 and 2011 Christchurch earthquakes occurred, when people started paying attention to the monitoring system. [5]
In December 2016 GeoNet got a funding boost of up to $3 million to improve its monitoring of and responses to natural hazards. This followed criticism of the response to the 2016 Kaikōura earthquake, especially the time it took for a tsunami alert to be issued. [6]
In January 2019 an earthquake occurred in the Kermadec Islands and another occurred a few minutes later in Whanganui. Because it takes a few minutes for the wave forms to travel to the mainland, the monitoring system detected the two earthquakes at the same time, and was tricked into thinking that a magnitude 6 earthquake had occurred in the East Coast. [7] A similar error occurred in 2012. [8]
The GeoNet website allows people to submit felt reports and to describe the intensity of the shaking. People can choose to submit a "detailed" felt report which consists of 40 questions. After the report is submitted, a coloured square is placed on a map, at the user's location. Most people make correct submissions, although some people purposefully make false reports or make mistakes, such as a VPN causing the website to not retrieve the user's location correctly. Aucklanders have a reputation for describing small earthquakes, including ones that cannot be felt in Auckland, as having "strong" or "extreme" shaking. Sometimes people try to draw images on the map using the coloured squares, such as a phallus. [9]
In 2023, GeoNet introduced a "shaking layers" map. Rather than showing squares at the locations of felt reports, it shows the median shaking at a given location. This includes locations where no one has submitted a felt report, and avoids showing possible false reports. [9]
Shortly after a large earthquake, Civil Defence may use the felt reports to gather information, such as power and communications outages, before the agency can gather information from other sources. An example of this is after the 2016 Kaikōura earthquake, where there was a lack of felt reports in Kaikōura, which suggested that there were outages there. [9]
Earthquakes are not the only felt reports that the website receives. It also receives reports of tsunami, with over 17,000 reports by 2020. [9]
The earthquake with the most felt reports on GeoNet had a magnitude of 6.0 and was located north-west of Paraparaumu, which gathered 60,688 felt reports in 2023. [10]
Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a particular earthquake. Earthquake shaking generally occurs in all three directions. Therefore, PGA is often split into the horizontal and vertical components. Horizontal PGAs are generally larger than those in the vertical direction but this is not always true, especially close to large earthquakes. PGA is an important parameter for earthquake engineering, The design basis earthquake ground motion (DBEGM) is often defined in terms of PGA.
Seddon is a small town in Marlborough, New Zealand. It is located 25 kilometres (16 mi) south of Blenheim, close to the mouths of the Awatere and Blind Rivers and the Lake Grassmere salt works.
GNS Science, officially registered as the Institute of Geological and Nuclear Sciences Limited, is a New Zealand Crown Research Institute. It focuses on geology, geophysics, and nuclear science.
An earthquake warning system or earthquake alarm system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for rapidly notifying adjoining regions of a substantial earthquake once one begins. This is not the same as earthquake prediction, which is currently not capable of producing decisive event warnings.
The 1855 Wairarapa earthquake occurred on 23 January at about 9.17 p.m., affecting much of the Cook Strait area of New Zealand, including Marlborough in the South Island and Wellington and the Wairarapa in the North Island. In Wellington, close to the epicentre, shaking lasted for at least 50 seconds. The moment magnitude of the earthquake has been estimated as 8.2, the most powerful recorded in New Zealand since systematic European colonisation began in 1840. This earthquake was associated with the largest directly observed movement on a strike-slip fault, maximum 18 metres (59 ft). This was later revised upward to about 20 m (66 ft) slip, with a local peak of 8 m (26 ft) vertical displacement on lidar studies. It has been suggested that the surface rupture formed by this event helped influence Charles Lyell to link earthquakes with rapid movement on faults.
The 1843 Whanganui earthquake occurred on 8 July at 16:45 local time with an estimated magnitude of 7.5 on the Mw scale. The maximum perceived intensity was IX (Violent) on the Mercalli intensity scale, and possibly reaching X (Extreme). The epicentre is estimated to have been within a zone extending 50 km northeast from Whanganui towards Taihape. GNS Science has this earthquake catalogued and places the epicentre 35 km east of Taihape, near the border of Hawke's Bay. This was the first earthquake in New Zealand over magnitude 7 for which written records exist, and the first for which deaths were recorded.
The 2009 Dusky Sound earthquake was a Mw 7.8 earthquake that struck a remote region of Fiordland, New Zealand, on 15 July at 21:22 local time. It had an initially–reported depth of 12 km (7.5 mi), and an epicentre near Dusky Sound in Fiordland National Park, which is 160 km (99 mi) north-west of Invercargill. It was the country's largest earthquake magnitude since the 1931 Hawke's Bay earthquake, but caused only minor damage and there were no casualties. A tsunami accompanied the event and had a maximum measured run-up of 230 cm (91 in).
The 2010 Canterbury earthquake struck the South Island of New Zealand with a moment magnitude of 7.1 at 4:35 am local time on 4 September, and had a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. Some damaging aftershocks followed the main event, the strongest of which was a magnitude 6.3 shock known as the Christchurch earthquake that occurred nearly six months later on 22 February 2011. Because this aftershock was centred very close to Christchurch, it was much more destructive and resulted in the deaths of 185 people.
The 1869 Christchurch earthquake occurred at 8:00 am on 5 June, near New Brighton, with an estimated Richter magnitude of 6.0. The shock had a Mercalli Intensity of VII–VIII.
The 2013 Seddon earthquake measured 6.5 on the Mww scale and was centred in New Zealand's Cook Strait, around 20 kilometres (12 mi) east of the town of Seddon in Marlborough. The earthquake struck at 5:09 pm on Sunday 21 July 2013 at a depth of 13 kilometres (8 mi), according to GeoNet. The United States Geological Survey also measured the quake at 6.5, at a depth of 17 kilometres (11 mi). The quake caused moderate damage in the wider Marlborough area and Wellington, the nation's capital city 55 kilometres (34 mi) north of the epicentre. Only minor injuries were reported. Several aftershocks occurred during 21–29 July.
The 2013 Lake Grassmere earthquake was a magnitude 6.6 earthquake that occurred at 2:31:05 pm (NZST) on Friday 16 August 2013. The epicentre was located about 10 km south-east of Seddon, under Lake Grassmere, with a focal depth of 8 km. The earthquake caused significant land damage in the local area, with landslips blocking roads, including the main highway between Blenheim and Christchurch. Buildings in Seddon were damaged, with some being declared uninhabitable. The earthquake was widely felt in both the North and South Islands of New Zealand.
The 2014 Eketāhuna earthquake struck at 3:52 pm on 20 January, centred 15 km east of Eketāhuna in the south-east of New Zealand's North Island. It had a maximum perceived intensity of VII on the Mercalli intensity scale. The magnitude 6.2 earthquake was followed by a total of 1,112 recorded aftershocks, ranging between magnitudes 2.0 and 4.9.
The 2016 Te Araroa earthquake was an earthquake measuring 7.1 on the moment magnitude scale that occurred at 04:37:55 NZST on 2 September 2016. The epicentre was located 125 km (78 mi) north-east of Te Araroa off the East Cape of the North Island of New Zealand with a focal depth of 22 km (14 mi). The earthquake was widely felt throughout the North Island and in the upper South Island. There were no reported casualties, and buildings predominantly suffered only a little bit of damage.
The 2016 Kaikōura earthquake was a Mw 7.8 earthquake in the South Island of New Zealand that occurred two minutes after midnight on 14 November 2016 NZDT. Ruptures occurred on multiple faults and the earthquake has been described as the "most complex earthquake ever studied". It has been subsequently modelled as having a megathrust component set off by an adjacent rupture on the Humps Fault. It was the second largest earthquake in New Zealand since European settlement.
The 2003 Fiordland earthquake struck the remote region of Fiordland in the South Island of New Zealand on 22 August 2003, at 12:12 am NZST. The epicentre was 12 kilometres (7.5 mi) deep, and was thought to be near Secretary Island at the entrance to Doubtful Sound. At 7.2 Ms magnitude, it was one of the largest quakes in the country for some time, and was the largest shallow quake since the 1968 Inangahua earthquake. There was an aftershock two hours later at 2:12 am, followed over several days by frequent small tremors; two months after the earthquake, there had been 8,000 aftershocks.
The 2021 Kermadec Islands earthquakes were a series of earthquakes with magnitudes of 8.1 and 7.4 that occurred at 19:28:31 UTC on 4 March 2021. The epicentres were located southeast of Raoul Island in the Kermadec Islands, part of the New Zealand outlying islands. The main magnitude 8.1 earthquake was preceded by a magnitude 7.4 foreshock and followed by a magnitude 6.1 aftershock. A separate, unrelated magnitude 7.3 earthquake occurred off the coast of the North Island of New Zealand, approximately 900 km to the south, several hours before the main quakes. More than a dozen aftershocks exceeded magnitude 6.
The Kaikōura Canyon is a geologically active submarine canyon located southwest of the Kaikōura Peninsula off the northeastern coast of the South Island of New Zealand. It is 60 kilometres (37 mi) long, and is generally U-shaped. The canyon descends into deep water and merges into an ocean channel system that can be traced for hundreds of kilometres across the deep ocean floor. At the head of the Kaikōura Canyon, the depth of water is around 30 metres (98 ft), but it drops rapidly to 600 metres (2,000 ft) and continues down to around 2,000 metres (6,600 ft) deep where it meets the Hikurangi Channel. Sperm whales can be seen close to the coast south of Goose Bay, because the deep water of the Kaikōura Canyon is only one kilometre (0.62 mi) off the shoreline in this area.
In 1914, two earthquakes shook the upper North Island of New Zealand; on Wednesday 7 October and Wednesday 28 October. They were large and shallow, with their epicentres close together northwest of Ruatoria in the Gisborne District. The earthquakes were felt strongly throughout the East Cape area, most noticeably in areas east of the epicentre such as Waipiro Bay, with a large amount of damage occurring in Tokomaru Bay in particular. One person was killed by a landslide near Cape Runaway.