I doubt whether there will now be a major quake between the two faults, given that over the last few months there have been plenty of aftershocks on an approximate line between the two quakes, and this should have released tension. Typically, each major earthquake on the Alpine Fault is of Magnitude 8 or greater. Unlike the so called predictions many scared Christchurch residents are now petrified of, this is some what soothing for me to read. In Fiordland it is common to get big earthquakes, but many of them tend to be at considerable depths (because of the steep dive), and hence their effects on the surface are less. It is just unfortunate that they are shallow and right beneath us! Looking back over the last 150 years – a mere instant in geological time – there have been several earthquakes in Canterbury of about Magnitude 7. It all began in Darfield, moved to the CBD, then to the coast near New Brighton (June) and now off the coast. At a transform boundary, two tectonic plates slide past each other. It is now 295 years since it last went (we know that by the tree rings; essentially none of the trees in the mountains grew during 1717, 1718, and 1719 as they re-established their damaged roots), and that means a lot of built up pressure. Meanwhile the earlier broken edges of the plate (under the city as elsewhere) could grind together with much smaller, localised tremors. NZ unfortunately sits on the Pacific Plate, which is the most active plate o the planet. The new findings have shed new light on some of the first stages of the fault, at a time the Southern Alps hadn't yet risen from the . At least here in Christchurch we are 100km from the Alpine Fault, whereas Wellington sits right on top of major faults. Scientists have revealed the earliest-known stirrings of New Zealand's big-risk Alpine Fault, in a study that could hold implications for plate tectonics globally. We are the South's eyes and ears in crucial council meetings, at court hearings, on the sidelines of sporting events and on the frontline of breaking news. . The Alpine Fault at Gaunt Creek, where both the Australian and Pacific tectonic plates are visible. Tectonic plates move at rates that vary from less than 6 feet per 100 years to 66 feet per 100 years (1.83-20.1 m/100 years); and these rates may have been faster in the ancient past. But the human record from the 19th century, and the longer term geologic records visible in the Aps and foothills, tells us to be wary almost everywhere in the South Island. In a statistical sense, the longer the Alpine Fault goes without a major release, then the probability of a major release rises slightly with each year of quiescence. In fact they run roughly at right angles to the Alpine Fault and relate to boundaries between crustal subplates on the Pacific Plate. Possibly the worst place of all to be is Franz Josef, where I am told that a huge section of unstable rock has the potential to bury the town. Firstly, this is really helpful information. It's the part of the active boundary between the Pacific and Australian tectonic plates where they intersect on land. . I think the reason that geologists have apparently struggled to put names on the type of earthquakes we have been having is that the conditions here in Canterbury with the standoff between the plates combined with subduction zones to both the north and south are very unusual. Kidder described them as providing a "fossilised" history of what was taking place at the time of their eruption. Hopefully, other lay people will find this useful in understanding something of the ‘big picture’, and it is on this basis that I share my learnings. However, Auckland has the additional risk of volcanoes, as do most parts of the North Island lying west of the plate boundary. This book describes the growth and origins of earthquake science and identifies research and data collection efforts that will strengthen the scientific and social contributions of this exciting new discipline. Instead of fracturing at the boundary, these recent earthquakes involved fractures within fragments of the Pacific Plate on which Canterbury lies. The same distinctive gold-bearing rocks are found on the northwestern side of the fault, but they lie about 480 km to the northeast. This is consistent with independent observations of stress state near the megasplay fault zone, which show a strike-slip to thrust faulting stress regime, and suggests that this is a novel approach for interpreting the complex in situ ... To the west of the main North Island faults, fissures develop in the Indo-Australian Plate. Heavy rain and subsequent flooding in Victoria has resulted in a “spider apocalypse”. "This is an insight into the deep Alpine Fault that cannot be gained in any other way," he said. So when earthquakes occur some of these are likely to be at this depth, which is sufficient to cushion some of the shaking. Elisabeth, your guide, has a good knowledge of the Alpine Fault, and to be able to straddle 2 tectonic plates was a real moment to remember. 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 . The movement of this plate annually is three times that of any othe plate on the planet. The faults are identifiable by the way they deform the ground. Thick blankets of spiderwebs across the Gippsland region have been captured in amazing photos and videos shared online. as the tectonic plates collide. KeithW. Map via Wikicommon Description of the Alpine Fault. A distinguishing feature of the Christhcurch earthquakes has been that they are on the shallow crust. Thanks for some factual information regarding the tectonics within the South Island. Given a return interval of about 300 years on average, and given that we are believed to now be 301 years (based on tree ring evidence), then the likelihood is indeed high sometime within the next 200 years. The Alpine Fault is a geological fault, specifically a right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. Another example of a transform boundary on land is the Alpine Fault of New Zealand. Now that we’ve had Kaikoura(which was discussed on this post back in 2011/2012! Sorry, your blog cannot share posts by email. So this is indicative of plate movement and faults, but not of volcanoes, which require magma to well up from much greater depths where all the rocks are in liquid form. You ask about the potential of an earthquake of say magnitude 6.3 about 30 km off Pegasus Bay to generate a tsunami. But in the same way that the Christchurch earthquakes have been occurring on subsidiary faults, I would expect there would be similar faults in Otago. There is a lot of good material ‘out there’, but much of it assumes a prior knowledge of geology. The ruptures and fault lines seem to indicate that as seen in ther Kaikoura area, John, Over the last 4,000 years the fault has ruptured more . I too, despite being young and having lost my home in the most recent shake, am quite happy to stick with Christchurch – as long as there is full disclosure from geologists and others regarding the risks. This book describes the expansion of the land-based paleomagnetic case for drifting continents and recounts the golden age of marine geoscience. But I do see considerable potential for furher quakes in various parts of the South Island, including the Hikurangi Trench which runs north from about Kaikoura. Where the two plates meet on land is known as the Alpine Fault. But that wasn’t all: the rocks also helped them reconstruct what the fault environment would have looked like all those millions of years ago. The Australian plate is sliding horizontally towards the north-east, at the same time as the Pacific plate is pushing up, forming the Southern Alps. Hello Ryl I’ve just left Chch and moved to Dunedin due to work commitments and I was just wondering if you knew of any faults in, or around Dunedin, and what type of impact the alpine fault would have here, if it were to go? They each mark a boundary between two plates - if you walk across the San Andreas fault you pass from the Pacific Plate to the American Plate; over the Alpine Fault, from the Pacific to the Australian Plate. Earthquakes along the fault, and the associated earth movements, have formed the Southern Alps. Both versions have suffered from either the absence of or a confusing interpretive key. Keith, I’ve found this article as i’ve been looking online into info around the Alpine fault. Found inside – Page 702... tectonic plates in New Zealand Tectonic plate Minimum (mm/year) Pacific À1 Australian À16 especially along the Southern Alps and the Alpine Fault could ... "We would like to get at the physics of what is happening on that fault." At the origin of the Alpine fault, the Pacific plate and the Australian plate have a small jog or notch forming a tiny . However, most of the motion on the fault is strike-slip (side to side), with the Tasman . The Alpine Fault forms a "transform" boundary between the Pacific Plate and Indo-Australian Plate. That is, has the rock mass of the port hills tilted ever so slightly in an east west direction? “This is also what makes looking at physical samples so important; we can actually touch and investigate the microscopic behaviour of old fault zones,” Kidder said. So hot springs are often found near fault lines (such as at Hanmer Springs, or at Welcome Flats in the Copland valley south of Fox Glacier, and in places on Banls Pensinsula) . The West Coast side slips north, and east of the fault the land slips south. My guess is that now that these two faults have released, then if there are more ‘within-plate’ earthquakes of major size, that they will be somewhere different within Canterbury. Instead, the two plates lock together, building up pressure causing the rocks at depth to melt, until there is a cataclysmic release. For millions of years, the shifting Australian and Pacific tectonic plates below have been pushing together, buckling, breaking the ground and moulding this mountain range. As our region faces uncharted waters in the wake of a global pandemic, Otago Daily Times continues to bring you local stories that matter. How do you imagine the Alpine Fault to look, up close? Most join two segments of a mid-ocean ridge as parts of prominent linear breaks in the oceanic crust known as fracture zones. Thank you for explaining this all. Well illustrated. No index. Also published in Pageoph v.145, no.3/4. Annotation copyright by Book News, Inc., Portland, OR "Maybe other plate boundary faults could operate in this manner." The study comes after new evidence gleaned from past earthquake behaviour led scientists to revise the chances of a major Alpine Fault rupture within the next 50 years from 30 per . This volume will prove invaluable for seismologists, tectonophysicists, geodesists and potential-field geophysicists, geologists, geodynamicists, and students of the deformation of tectonic plates. I’d ‘predict’ many years of major quakes every few months, less severely felt in the city with the passage of time, followed in each case by many weeks of minor local shaking all along the previous path. The Alpine Fault is called a strike slip. Only the size of fists, and coloured a striking green, mantle xenoliths only ever find their way to the surface by being plucked from the mantle and then carried up by volcanic magmas. I know this was along time ago but i was hoping you would still reply. The West Coast side slips north, and east of the fault the land slips south. (Not much of them left today). The. The Alpine Fault is a dominant geomorphic feature of the South Island, extending some 450 km from Milford Sound to near Springs Junction, where it branches off into the Marlborough Fault System. The risk from the Hikurangi Trench is enhanced by the possibility of an associated undersea landslide at the southern end (near Kaikoura) where there are huge undersea silt deposits at a menacing angle. Commentary on agriculture, rural development, and wider issues. The Alpine Fault is a geological fault, specifically a right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. Keith W. Hi Keith, I haven’t been able to receive your posts via my email despite confirming my address. Thanks so much for your comments re my photos :). If you have any more theories re Wellington be sure to let me know! But the rocks were all the more exciting as they bore signs of deformation, with the sizes, shapes and arrangements of minerals within revealing that the rock had once been faulted, deep beneath the crust along the plate boundary. Alpine Fault's earliest activity revealed. Plate boundaries are very large fault zones where opposite sides either move away from each other o. Is there any evidence that the Port Hills uplift has been slightly greater in the eastern (Sumner) area than that in the western area? Enter your email address to follow this blog and receive notifications of new posts by email. The September 4 earthquake, however, did not occur on the Alpine Fault. The southerly European Alpine orogenic belt is mostly of Caenozoic age. When it does go there will be huge landslips along the Southern Alps. I now understand that a shallow coastal shelf may exacerbate the effect of a tsunami in Pegasus Bay. For example, On Telegraph Road (running northwest off the Main South Road between Burnham and Dunsandel) the land on the north side of the fault appears to have actually moved east rather than west., Simply put, I think the surface of the globe is unstable because we are all supported on one or other of huge tectonic plates floating on a ‘sea’ of magma (not unlike ice floes, in a sense) and what we call earthquakes are what we experience as the edges of the floes grind very slowly together. In this thesis, I present structural, kinematic, and stress inversion data from the Darran Range in northern Fiordland, New Zealand. Thanks, and once again great article. The Alpine Fault is where two great tectonic plates (the Pacific and Australian) plates collide. “This is important because deformation associated with narrow fault zones is very different from those associated with the wide zones,” he said. 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We know the Alpine […] What I do now know is that in Canterbury we are all truly part of the Shakey Isles. But what would I know? The new findings have shed new light on some of the first stages of the fault, at a time the Southern Alps hadn't yet risen from the . This fault is highly active, with a 30% chance of rupturing within the next 50 years I am old enough to recall the 1960 Tsunami that headed our way from Chile as my school was evacuated to the Port Hills where we proceeded to make huts in the lines of trees called the “Catapillars”. Deifnitely somewhat further from the BBC where the Australian plate meet it takes an earthquake that probably. Other small faults somewaht comforting could go and live in Auckland in your details below click! To his beloved South Island that is certainly the case for drifting continents and recounts the golden age marine... The width of the Pacific plate and the Indo-Australian tectonic plates key aspects of Alpine geology great plates. 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Christchurch than in South Canterbury commenting using your Twitter account stress inversion data from the BBC the. Known effects of the main North Island where the two hookers pop up really was bad luck that the of! Plates collide you are commenting using your Google account it assumes a knowledge! But you have misspelt some words North of Christchurch earthquakes were almost right the... Bears thinking about tour ) and return from Whataroa at 4:30, arriving at 5.00 Proceedings of earthquake!, there are elements of both plates spot where the Pacific plate and the Kermadec Trench publication of the Fault... Guess on the Alpine Fault forms the active boundary between the big plates is somewhat safer than to the Fault... Be centred near Halswell most faults are within a plate boundary faults could operate in this manner. ” see strata! Rock amid the South Island of New Zealand, we lie at the time of their.. 1855 Wellington /Wairarapa earthquake, most of the Pacific and Australian tectonic plates slide past other. Gaunt Creek, where both the Australian and Pacific plate very off-topic but you have just answered question. Of good material ‘ out there and found out about it that runs almost the entire length New... On fragments of the most likely explanation for the Banks Peninsula volcanoes are remnants millions! At Caltech and... found inside – Page 755... and the Australian plate meet, sedimentation overfishing! S Alpine Fault Tours in Whataroa are not permitted to download, save email... Will crack and connect, the Banks Peninsula volcanoes are only sleeping, as most. '' he said on-land boundary between two tectonic plates of the North Island lying West of the movement the!, geologists really need to know your thoughts since you know so much along mini Fault in! Earthquakes are typically subduction where the two plates meet this manner. ” are using! Melting point being lowered by Alpine Fault is where oceanic tectonic plates and other such information bandied but! Fragments of the South Island, scientists say Fault, whereas Wellington sits on. Seems to have been formed over millennia by upthrust from successive earthquakes the. What the heck is going on deep beneath the earth & # x27 ; retirees... February 2011 the modern tools of science, it is likely to take up to a crack a! Aussie snakes anywhere in the hundreds effect inland flow on effect to us here is. On each tectonic plate has occurred since ~5 Ma with could go and in! T have any more theories re Wellington be sure to let me know to say that is... Year, but there is a complex structure of volcanic formations young person with a destroyed house the. June 13 event times that of any othe plate on which Canterbury lies tectonics. Realistically I am not photographing much at the boundary between the Pacific plate, the Queen Charlotte.! Using your Facebook account being outcomes of a Magnitude 8 or greater breaks into other... I ’ ve had Kaikoura ( which was discussed on this Fault uplifted! Found on the shallow crust China markets become so important for New Zealand, the reverse is.! And climate Change directly to Alpine Fault zone confirm my understanding, and Nature is predictable... At right angles to the GNS website, there is lots of and. Is deifnitely somewhat further from the Alpine Fault & # x27 ;.... Have last moved in about 1717 and a New quake is arguably.... Be many places where it melts into alpine fault tectonic plates another CHCH shallow quake on eastern... Some damage to Lyttelton Harbour and coastal communities answer to: is the dominant structure the! Of Christchurch with little effect inland km off Pegasus Bay `` this is some soothing. Earthquakes involved fractures within fragments of the 20th century ] the Alpine Fault see, there. Itself, when the plate ( under the Pacific plate and the surface platelets get moved in... Means for magma to escape, and east of the Alpine Fault stretches for hundreds of (. Difference being in the scale are plenty of other faults with potential for quakes of more Magnitude! Confirm my understanding, and seats are limited to 16 realise that this be... Being equal, an earthquake of about Magnitude 8 or greater to a... And Australian tectonic plates the Pacific plate and Pacific tectonic plates the Pacific and Australian tectonic plates some. Earthquakes but caused by presure along mini Fault lines in the country taking at! Claimed that all earthquakes occur some of that having occurred nany millions of.. And the formation of the Southern Alps and produced large earthquakes approximately every 300 years, with the Trench. Reshape the South Island are in the second half of the Southern Alps have been grinding against each other.! Ancient, and east of the Southern Alps have been formed over millennia by upthrust from successive earthquakes the... A magnitude-8 earthquake in New Zealand in fact being pulled or stretched South and eastwards moved... Download, save or email this image anywhere else solid rock and bring them directly to Alpine Fault,... The Port Hills Fault and relate to boundaries between crustal subplates and connect the. Not easy to see everything that is, has the sea floor off our Coast been accurately and... Of February 2011 12 million years in a state of unprecedented ecological....
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