Evidence for Ancient Alpine Fault Earthquakes. (2014) reported the probability of occurrence of an Alpine Fault Magnitude 8 earthquake in the next 50 years as 30%, resulting in an estimated $10 billion in economic cost. High Heat Flow and Geothermal Gradient. Last year, GNS Science earthquake scientist Rob Langridge and Victoria University paleoseismologist Jamie Howarth uncovered evidence of a previously unknown quake that took place sometime between 1740 and 1840. At Hokuri Creek, an exposed outcrop enabled the scientists to identify layers deposited by Alpine Fault earthquakes. There isn't enough evidence yet to favour one scenario over the others, Dr Langridge said. "One of the outcomes of this study is that you should expect a shorter recurrence interval of strong shaking at fault section ends. "One of the real challenges with the Alpine Fault - because it is so bush-covered - is actually finding sites that have been cleared and therefore can be studied," said Dr Langridge. The Alpine Fault is sometimes compared with California’s San Andreas Fault, being another fast-moving strike slip fault near a plate boundary. In addition to the newly discovered quake, they found more evidence for three big quakes - one between 1084 and 1276, a second between 1250 and 1580, and the most recent big one, which they dated to between 1673 and 1792. The 100-metre and 150-metre probes of stage one were … The findings published in the Bulletin of the Seismological Society of America suggest that some places along the fault, particularly around the towns of Hokitika and Greymouth, could experience strong ground shaking from Alpine fault earthquakes more often than previously thought. Large earthquakes are less common along the central Alpine Fault, where the plates are not subducting and the forces are accommodated in different ways. Discussion: Maximum Earthquake Magnitude. Alpine Fault Locking Inferred from Geodetic Data. The last such earthquake took place in 1717. But the findings prove there could be strong quakes on the fault in between the big ones. The investigation found the mean interval between large earthquakes on the fault is 330 years and two thirds of the intervals were between 260 and 400 years. “The San Andreas Fault, being on the opposite side of the Pacific plate, it is like our distant brother or whanau — family,” said Langridge. The 19th century quake was perhaps only a partial-section slip, Dr Langridge said, proving activity on the Alpine Fault is more complex than previously thought - particularly in its north, where it meets up with other fault zones, such as the Marlborough Fault System. The Alpine Fault runs 400km up the South Island, along the western edge of the Southern Alps. The 2012 paper suggests simply that fault zones are sites of high fluid pressure gradient, and that “dynamic pressurisation likely promotes earthquake slip.” Stage two of the deep-drilling programme is scheduled for 2014. However, the plates are locked and when they overcome these barriers, they produce large but … How will the next Alpine Fault earthquake compare to the M7.1 Darfield earthquake of 4 September 2010? At John O'Groats, core samples showed layers similar to those found at Hokuri Creek. Discussion: Alpine Fault Rupture Mechanisms. This means, for instance, that an Alpine Fault earthquake of M8.1 would release about 30 times more energy that the Darfield earthquake of M7.1. The Alpine Fault is sometimes compared with California's San Andreas Fault, being another fast-moving strike slip fault near a plate boundary. Langridge said researchers in California and New Zealand have a long history of earthquake science collaboration and are learning from each other about the treatment of active faults and fault segmentation for seismic hazard models. The effect of fluid differentials on an Alpine Fault earthquake is obviously significant but presently unquantified. An Alpine Fault earthquake will likely rupture … It forms the sharp line separating the snow-covered Southern Alps in the east from the low coastal plain bordering the Tasman Sea in the west. “Once we started working there [at the Staples site] the story really grew in large part because of the richness of dateable organic material in the trenches.”. Numerous experts say it will be the largest natural disaster of modern times in New Zealand. The alpine fault earthquake will alter tectonic stress distribution, and other faultlines may rupture in the days or years following it. Bulletin of the Seismological Society of America, 2020; DOI: 10.1785/0120200116. Alternatively, the quake might have been centred further north, the rupture spreading along the fault to the southwest where Dr Langridge and his team did their digging; or possibly triggered by a separate quake in the Marlborough Fault System. In the past ~1000 years there have been four large earthquakes on the Alpine Fault and two large … Related video: Alpine Fault overdue for magnitude 8+ quake - scientists. Berryman et al. The last such earthquake took place in 1717. This is not a regular pattern, but enough to suggest there is a high probability of a large earthquake in the next 50 years. The next Alpine Fault earthquake would likely also be a long-duration event – unzipping the crust for as much as three minutes - because of the sheer length of the fault. Recent research has found that the average time between large earthquakes on the fault is 330 years. The rupture will produce one of the biggest earthquakes since European settlement of New Zealand, and it will have a major impact on the lives of many people. The Alpine Fault is sometimes compared with California’s San Andreas Fault, being another fast-moving strike slip fault near a plate boundary. There have been no major historical earthquakes on the Alpine Fault. 7.4 magnitude quake hits off NZ's coast, Kiwis warned to stay out of water, The South Island regions an Alpine Fault quake would affect most, Alpine Fault overdue for magnitude 8+ quake - scientists, Copyright © 2020 MediaWorks TV - All Rights Reserved, By subscribing you agree to our Terms of Access and Privacy Policy, uncovered evidence of a previously unknown quake. It runs as a single structure for over 500 km. Evidence is growing the South Island's Alpine Fault, capable of devastating earthquakes of magnitude 8 and above, ruptures more frequently than previously believed. During the field trip follow the line of the Alpine Fault as it is crossed by roads, bridges, rivers, mountains, power lines, and phone lines from Arthur's Pass to Whataroa on the West Coast. This is more recent than the 1717 quake, which has been estimated at magnitude 8.1 - nearly three times stronger than the 2016 Kaikoura earthquake - and shifted one side 8m relative to the other. The last major earthquake on the Alpine Fault was in 1717, so we're already a little overdue for one of the biggest earthquakes in New Zealand's modern history. A new model has simulated the disruption a major Alpine Fault earthquake would have on the South Island's transport network - cutting off the West Coast for at least a week. The best paleoseismic evidence to date suggests the southern and central sections of the Alpine Fault, at the boundary separating the Australian and Pacific tectonic plates, typically rupture during very large full-section earthquakes of magnitude 7.7 or larger. Radiocarbon dating places this earthquake between 1813 and 1848. The Alpine Fault is overdue for an earthquake that could reshape the South Island, scientists say. Deep low-frequency earthquakes indicate migration of magmatic fluids beneath Laacher See... Alaska Centennial Nugget : Largest Gold Nugget Ever Found in Alaska, New source of energy-critical lithium found in supervolcanoes, Marine life recovery following the dinosaurs’ extinction, New trilobite fossil reveals cephalic specialization of trilobites in Middle Cambrian. The science While we can’t predict when earthquakes will occur, scientific research has shown that the Alpine Fault has a regular history of producing large earthquakes. The four most recent earthquakes uncovered by the researchers at the site range in dates from 1084 to 1848. The fault, which runs about 600km up the western side of the South Island between Milford Sound and Marlborough, poses one of the biggest natural threats to New Zealand - especially the West Coast, Canterbury and Otago. What will the climate be like when Earth’s next supercontinent forms? Some studies looking 100 years out have concluded it's as much as 85 percent likely. “Because of the recurrence times of earthquakes though, you obviously have to wait a long time to see the effects of such fault behavior.”, “That’s why paleoseismology is a vital tool in understanding faults,” he added, “because otherwise we’d have only short insights into the past.”. New Zealand earthquakes cause total DEVASTATION The Alpine Fault runs right through the heart of New Zealand's glacier county on the country's south island. Citing Literature. Scientists trenched a site near the Toaroha River, south of Hokitika, and found evidence of the more recent quake in the northern part of the 600km-long fault's central section. After trenching along the fault at the Staples site near the Toaroha River, however, Robert Langridge of GNS Science and colleagues uncovered evidence of a more recent earthquake along the northeastern end of the fault’s central portion. For every one unit increase in magnitude (e.g. But new evidence of a 19th century earthquake indicates that in at least one portion of the fault, smaller earthquakes may occur in between such large rupture events. Slow earthquakes occur continuously in the Alaska-Aleutian subduction zone, Bismuth Crystal “Artificially grown bismuth crystal”, Incredible moment Anak Krakatau erupts, Oct 2018, Otman Bozdagh Mud Volcano Eruption “Sep23, 2018”, SAGA GIS – System for Automated Geoscientific Analyses, ParaView “Open Source Visualization For Geoscience”, Continents prone to destruction in their infancy, study finds. An Alpine Fault rupture could produce one of the most destructive earthquakes since European settlement of New Zealand because of its geologic characteristics. The Alpine Fault is the dominant structure defining the Australian-Pacific plate boundary in the South Island of New Zealand. If the Alpine Fault does trigger another magnitude 8-plus quake in the near future, GNS says it will "have a major impact on the lives of many people", and likely be "one of the biggest earthquakes since European settlement of New Zealand". Langridge and colleagues said that there isn’t enough evidence yet to favor one of these scenarios over the others. An Alpine Fault earthquake will be felt by every South Islander and likely many North Islanders, too. In between earthquakes, the Alpine Fault is locked. The South Island Alpine Fault Earthquake Response (SAFER) Framework provides a concept of coordination of response and priority setting across all six South Island Civil Defence Emergency Management (CDEM) Groups and their partner organisations in the first seven days of response. "Given what we know from geological studies of the Alpine Fault, we're anticipating a major magnitude 8.0-plus earthquake, rupturing 500km of the crust, so the shaking will be felt throughout the South Island, but the intensity and duration will ultimately depend on what happens on the fault." The Alpine Fault has a high probability (estimated at 30%) of rupturing in the next 50 years. The last such earthquake took place in 1717. And the towns of Hokitika and Greymouth are sitting right in the firing line. Langridge said researchers in California and New Zealand have a long history of earthquake science collaboration and are learning from each other about the treatment of active faults and fault segmentation for seismic hazard models. Credits: Video - Newshub; Image - NASA/file. The Alpine Fault stretches for hundreds of miles (kilometres) like a spine along New Zealand's South Island. The Alpine Fault is a geological fault, known as a right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. The Alpine Fault is one of the world's major plate boundaries and New Zealand's most hazardous earthquake-generating fault. The length of the rupture will be up to 400 km, eg. Analysis of tree ring patterns in 2018 suggested it happened in 1717, prior to European settlement when there were few people in the South Island. Piecing together the Alaska coastline’s fractured volcanic activity, Former piece of Pacific Ocean floor imaged deep beneath China, East African Rift System is slowly breaking away, with Madagascar splitting into pieces, Researchers discover ‘missing’ piece of Hawaii’s formation. This fault has suddenly moved or ruptured four times in the past 900 years, each time causing an earthquake of about magnitude 8. Because of this during the mid 20th century it was speculated that the Alpine Fault creeps without making large earthquakes. Langridge said researchers in California and New Zealand have a long history of earthquake science collaboration and are learning from each other about the treatment of active faults and fault segmentation for seismic hazard models. Research has found a big one happens every 300 years or so, and GNS Science estimates there's about a 30 percent chance of another happening in the next 50 years. Discussion: Alpine Fault Rupture Scenarios. By analysing sediment deposited at two sites in Fiordland, scientists have established that the Alpine Fault has ruptured 27 times over the last 8000 … Conclusions. The best paleoseismic evidence to date suggests the southern and central sections of the Alpine Fault, at the boundary separating the Australian and Pacific tectonic plates, typically rupture during very large full-section earthquakes of magnitude 7.7 or larger. The most recent earthquake could represent a “partial-section” rupture of only the central portion of the Alpine fault, a rupture of the fault’s northern section that continued southwest into the central segment, or even triggered slip from a rupture along the nearby Marlborough Fault System. on Haast and spreading north to Ahaura. However, the findings do suggest that seismic activity on the Alpine Fault is more complex than suspected, particularly along its northern reaches where the plate boundary transitions into another fault zone. Alpine Fault Dynamic Rupture Model. Note: The above post is reprinted from materials provided by Seismological Society of America. Simulation shows widespread damage if Alpine Fault ruptures, 'What was that?!' Recent research by GNS Science has extended our knowledge of the Alpine fault earthquake record back through the past 8,000 years. from M4 to M5) there is about a 30-fold increase in energy release. All these cities have experienced severe earthquakes since European settlement. Alpine Fault Geometry and Physical Properties at Depth. Using radiocarbon dating, they've narrowed down the likely date of the most recent quake, measuring magnitude 6 or 7 (so potentially as strong as the Christchurch quakes) to between 1813 and 1848. "Once we started working there, the story really grew in large part because of the richness of dateable organic material in the trenches.". The fault is a strike-slip boundary in which the Australian Plate and the Pacific plate are moving horizontally past each other. However, it is now inferred by multiples lines of evidence that the Alpine Fault ruptures creating major earthquakes about every few hundred years. How often does the Alpine Fault cause earthquakes? It is very difficult to predict whether an Alpine Fault earthquake could trigger any activity on the Marlborough Fault System and the Hikurangi Subduction Zone, but it is highly unlikely that a single earthquake could rupture right through from the Alpine Fault to the Hikurangi Subduction Zone. The largest city within the highest-risk zone is the nation's capital, Wellington, followed by Hastings then Napier. Because of the recurrence times of earthquakes though, you obviously have to wait a long time to see the effects of such fault behavior.". A rupture along the full length of the fast-slipping Alpine Fault on New Zealand’s South Island poses the largest potential seismic threat to the southern and central parts of the country. Robert M. Langridge, Pilar Villamor, Jamie D. Howarth, William F. Ries, Kate J. Clark, Nicola J. Litchfield. The events were confirmed by data collected from other nearby trenching sites and from geological deposits called turbidites, which are sediments shaken loose into a body of water by seismic activity, in lakes along the central section of the Alpine fault. But there has been as little as 140 years and as much as 510 years between Alpine fault earthquakes. Project AF8 is a collaborative effort to prepare for a magnitude 8 Alpine Fault earthquake. "By comparison, the Kaikōura Earthquake in 2016 ruptured a total fault length of 200km in the space of about two minutes," said Holden. The best paleoseismic evidence to date suggests the southern and central sections of the Alpine Fault, at the boundary separating the Australian and Pacific tectonic plates, typically rupture during very large full-section earthquakes of magnitude 7.7 or larger. “One of the outcomes of this study is that you should expect a shorter recurrence interval of strong shaking at fault section ends,” Langridge said. Evidence is growing the South Island's Alpine Fault, capable of devastating earthquakes of magnitude 8 and above, ruptures more frequently than previously believed. The Alpine fault is the longest active fault in NZ, measuring more than 600 km long, with the largest average long term slip rate (Yetton, 2000). As with many natural systems, there was a spread of intervals with the longest being about 510 years and the … Using techniques like these, scientists such as Mark Yetton of the University of Canterbury have found out that major earthquakes happened on the central Alpine Fault in 1100, 1450, 1620 and 1717. "An important outcome is that sites or towns near fault intersections and section ends may experience strong ground motions more frequently due to locally shorter rupture recurrence intervals," the study, published in the Bulletin of the Seismological Society of America this week, says. 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