Earth Science

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Tsunami Video

New Zealanders know by first hand experience that living on top of a plate boundary makes life unpredictable. The recent earthquake in Christchurch was just the latest example of that. I recently had the privilege of interviewing several Kiwis who had experienced first hand the power of a tsunami. Luckily for them they all escaped with no more than cuts and bruises, but many around them were not so fortunate. These tsunami events were overseas – in Thailand 2004 and Samoa 2009. However, it is worth remembering that New Zealand is one of the most ‘at risk’ countries in the world when it comes to tsunami hazard. In case you haven’t seen it on our GNS Science Youtube Channel here is a video of the vivid tsunami accounts, hosted by Hamish Campbell:

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NZ Volcano Fact Sheets

The GNS Science website now has 10 one page Fact Sheets on the main New Zealand volcanoes. They give details of the landforms, rock types and eruption histories, with colourful images and diagrams.These are great for a school project, or to print off and take with you when you go for a tramp up one of our volcanoes. Don’t forget that there is lots of detailed volcano information on our website as well as webcams and updates of volcano activity levels on our GeoNet site. Watch a video of scientists monitoring White Island Volcano, or follow some students whilst they check out the amazing Volcanic Landforms of Tongariro.

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Lake Rotomahana’s Secret Underworld

Cornel de Ronde is the world renowned GNS Science specialist in researching undersea volcanoes and hydrothermal activity. He has made numerous discoveries and had many adventures diving to the ocean floor in submarines of all shapes and sizes.Visitors to Wellington’s Te Papa Museum may recognise him from the “Deep Ride” submarine experience. In 1886 Mount Tarawera near Rotorua erupted with extreme violence for a few hours over one night in June. By morning, several settlements had been buried in hot ash and mud with the loss of over 100 lives, the world famous pink and white silica terraces had disappeared and a crater several kilometres long had opened up in a reshaped and devasted landscape. Lake Rotomahana, on whose shores the famous terraces had been located, had become part of the long, deep volcanic rift. Over time the lake refilled with water again to become a larger version of its former self.In January, Cornel will be leading a team of researchers from New Zealand and the US, to plumb the depths of Lake Rotomahana with two very high tech, automated underwater vehicles (AUVs). They will map the lake floor, identify the hydrothermal vents, and make numerous measurements of the chemical and physical properties of the lake water and hydrothermal fluids. (Permission of the Alexander Turnbull Library, Wellington, New Zealand, must be obtained before any re-use of this image of the Tarawera Eruption.) The detailed survey will enable the scientists to find out the fate of the Pink and White Terraces after the Tarawera eruption in 1886. These terraces were world famous in the nineteenth century for being the largest silica terraces on the planet, and for their outstanding beauty and grandeur. Visitors used to wander over the terraces and bathe in the bath tub shaped depressions Tineke Berthelsen is one of the science team. She will be managing some of the practical aspects of the project and operating equipment when the research team is on site in late January. We will be posting more information on this blog over the coming weeks. For a more in depth introduction to the project you can read the press release that has been publicised today. Bookmark this blog or link up to our facebook page if you want updates about the background and science of this unique research project.

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Julia Becker’s Observations following the Darfield Earthquake

Julia Becker is one of the Social Scientists at GNS Science. Her role is to understand the human response to natural hazards, and she works with other scientists and organisations to help plan for future disasters. I asked her to write a diary of her experiences of working in Christchurch in the week following the Darfield ‘Quake: 06/09/2010We arrive in Christchurch, two days after the earthquake. Driving into the city from the airport, much of the city looks quite normal. There are a few chimneys down and damaged brick fences. As we approach the city you start to see more damage, mostly to older brick buildings. Some are just a bit damaged with a few bricks fallen off while others’ facades have completely collapsed. There is quite a wide area around the city that is cordoned off and the cordons are blocked by police officers and military personnel. We have to take a big detour all the way around the city to reach our hotel. Many shops and supermarkets we pass seem to be operating. We drive past a clock tower and it has a big crack in it. At our hotel we drop our gear and then head to visit the city and regional emergency operation centres. They are very busy with many people coming and going, working away hard to respond to the earthquake. After having a few meetings with people to let them know we are here and providing offers of science and research support, we head back to our hotel for dinner and bed. 07/09/2010Small aftershocks in the night occasionally wake me from sleep. I wake at about 6.00 am. While the water is working there is uncertainty over potential contamination so I have to remember to brush my teeth with boiled water. All drinking water needs to be boiled as well. In the morning we reconnect with the regional emergency operations centre and begin to set up an office there from which the scientific research response can be coordinated. I speak briefly to Red Cross volunteers at the regional emergency centre and they say the welfare centres are being well used, with more people turning up after the aftershocks in the night. A little later two of us from GNS obtain official passes to enter the cordoned-off city centre and inspect the buildings from the outside. Many new buildings look like they have stood up well to the earthquake. The Christchurch Cathedral seems pretty sturdy too. There are a number of buildings scattered throughout the centre that have red placards indicating that they cannot be entered due to structural damage. In the afternoon we head out to the suburbs and see the impacts of liquefaction. A few suburbs have experienced significant liquefaction, and sand volcanoes have popped up out of cracks in ground. Residents have already begun to clear away the sand by shovelling it up and placing on the grass verge in front of their houses, and the council is driving by and collecting it in trucks. Port-a-loo toilets have been set up for residents who don’t have working sewerage systems.08/09/2010Sleep is again disrupted by aftershocks throughout the night. This morning before breakfast we are also rattled by a large 5.1 aftershock (scary!), followed by several smaller ones. After breakfast we visit the town centre to observe more of the building damage. We see a whole row of shops made of bricks where the front of the building has simply fallen away on to the pavement in front. Luckily the earthquake happened at approximately 4.30 am so there were few people on the streets at that time and people were not hit by the falling masonry. A restaurant is housed in one of these buildings, and as you look through the gaping hole left by the fallen bricks you can still see the tables set up and ready for customers. In the afternoon we visit the newly ruptured fault near Darfield. You can see where the fault has torn through several roads and fields. The rupture has offset the roads sideways and vertically. Initial repairs to the roads have been made to make them drivable again. You can also see where the fault has offset power pylons, trees and fences. At the very western end of the fault, an electricity substation is perched directly over the rupture and the surrounding fences and gates are twisted, but because the fault is quite distributed at this location the substation appears to still be intact and in working order. At the eastern end of the fault a house-owner is not quite so lucky, with the fault causing building damage to a resident’s home. 09/09/2010 Today we visit a couple of land use planners in Christchurch and discuss issues related to recovery. We discuss having a strategic vision for Christchurch when going into the rebuilding and recovery phase. Following our meeting we take a drive out to Pegasus township, a new subdivision located approximately 30 minutes drive north of Christchurch. Previous studies have shown the site has liquefaction potential. There are a number of houses built there already, and also some empty lots. Pegasus seems to have survived remarkably well and our untrained eyes could not see any significant cracking or liquefaction. It is suggested by the planners we speak to that geotechnical engineering works were undertaken when the subdivision was set up to try and avoid such problems. In the evening I attend a com munity meeting in Darfield. The meeting was set up with the aim of to giving residents information about the earthquake, providing discussion on how they might feel after the earthquake, and providing advice on practical issues that might need addressing (e.g. water pumps, insurance, finance, government support). At the end of the meeting two guest speakers tell a couple of funny tales to provide some light humour to the meeting. The meeting is well attended with nearly 400 people coming along. On our way ho me, driving down Riccarton Road we

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Scientists’ response to the Canterbury Earthquake

Whilst those of us in Wellington may have felt a short jolt and a bit of a wobble, the 7.1 magnitude earthquake hitting Christchurch on Saturday morning was an altogether different experience for the locals. People I have talked to referred to the noise of the quake as being one of the most powerful aspects of the experience. Different specialist teams from GNS Science immediately leapt into action to capture vital information about the origin and effects of the quake, and to keep authorities, public and news media updated. Web traffic has been very high with the GeoNet website receiving 15 to 20 million hits per day. This image is the seismic drum for McQueen’s Valley, near Christchurch on the Saturday afternoon. You can see how the aftershocks are very frequent. Some of them are up to magnitude 5.4, though scientists think a larger one of up to magnitude 6 is possible sometime in the next few days. This seismic drum is from the same time, but recorded in the far north up at Waipu. You can see how the weaker ground shaking has not reached that far, but many of the aftershocks are still recorded there. It is interesting to look at the way the waveforms change when they are recorded a lot further away from the epicentre. An initial flyover of the surface rupture revealed a fault trace about 22kms long in the Rolleston area to the west of Christchurch, with a maximum of 4 metres of horizontal and 1.5 metres vertical displacement. The surface rupture passed close by a few farm buildings and beneath two farm houses. The fault dislocated some hitherto undisturbed glacial river terraces, showing that it has not moved for a minimum of 16 – 18 000 years. Here is a video of the fault trace from the air: The Geonet seismologists started the analysis of the large number of aftershocks detected by the NZ network of seismometers, finding their locations and magnitudes, and using the information to interpret crustal stress and strain dynamics in the region. The data collection systems were thoroughly tested and have performed very well through this event. A team flew down to Canterbury and installed an array of extra seismometers which add further data as the aftershocks continue. Other GNS Science teams are now in the Christchurch area assessing and monitoring such things as: infrastructure damage, including water and sewage, fault and landscape mapping, risk engineering, high resolution GPS measurements, and further measurements and mapping of ground motion.

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Romanian Salt

Another place that I visited in Transylvania was the town of Torda, where there is a huge (1200 metre thick) salt deposit that formed about 18 million years ago. The salt can be found forming the sides of a nearby valley where it has been eroded by rainwater into pinnacles. The salt is 99% pure and the crystals form cauliflower like surfaces covering large areas. It has been mined since Roman times, and some of the undergound workings have become huge chambers up to 80 metres long, 50 metres wide and 40 metres high. The high relative humidity, constant temperatures, absence of dust and high concentration of sodium chloride particles in the chambers are regarded as beneficial for sufferers of breathing disorders (eg asthma, allergies etc). Large areas are equipped with playgrounds, a restaurant, internet access and even a church so that visitors can spend days at a time underground.

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Romanian Ice Cave

On a recent trip to Europe, I spent time in Romania, France and Italy. Here are some of the geological highlights I visited: This photo is an underground glacier in the Apuseni Park. This is an area of the Carpathian Mountains with over 200 limestone caves. The Focul Viu ice cave that we visited is one of several in Romania. There is about 25 000 cubic metres of ice which has accumulated as snowfall from a large hole in the ceiling of the cave ( along with branches and leaves from the surrounding forest). Due to the poor circulation, cold air sinks into the cave and maintains very low temperatures even in the hot summer months. An 8 metre ice core has been retrieved from this cave. A piece of wood from 7 metres down was dated at about 1700 years old.

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Under a cloud in the UK

Having arrived at Heathrow a few hours before the shutdown of all flights over Britain due to the volcanic eruption in Iceland, it has been fascinating to watch the unfolding impact as the flight ban has been extended through the last few days. As with an earthquake or tsunami, a geological process is suddenly thrown into the public consciousness, even though it originates from far away. In this case the process is relatively prolonged and there is no-one who has any idea of how long the eruption might last or how the winds might be moving the ash cloud a week from now. As well as having stressful consequences, there have also been benefits resulting from the ash cloud. I am staying in the south east of England, not far from Gatwick and Heathrow airports. For many people this is the first time ever that they are able to sit in their back yards and have a conversation without being drowned out by the roar of aircraft overhead. The weather has been sunny with clear skies, with no visible sign of the ash cloud that is causing so much disruption. News bulletins are filled with the scientific background, economic predictions, traveler’s personal stories and political commentaries. I have been increasingly grateful for my good fortune in having got here just in time, whilst wondering if my return journey at the end of April will be equally unaffected. There are direct lessons to be learnt for NZ too as Gill Jolly and Graham Leonard, both volcanologists at GNS Science, describe in this media release

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Tararua Range

With Uwe Morgenstern, also from GNS Science I hiked the length of the Tararuas just north of Wellington over 4 days. The Tararua mountains are a section of the ‘backbone’ of New Zealand. They are made of greywacke rock, pushed up by the tectonic forces of plate collision. Like most of New Zealand’s mountains, they form an obstruction at right angles to the prevailing westerly winds and are renowned for high winds and high rainfall – often making for tough tramping. Luckily for our trip we had very stable and clear conditions, a rare treat! We set out from the Putara road end near to Ekatahuna, at about 9am. After following a stream and hiking upwards in the forest, we came out into the open tussock after a couple of hours. It was quite cloudy through the day. This made for an amazing sunset as we continued along the ridge to Arete Hut which we reached after dark. For the final hour and a half we had to navigate by map and compass, with a bit of searching to finally reach our refuge for the night. Day 2 saw us following the ridge for hour after hour. the distant point on the horizon was our objective for the night and again we reached Jumbo Hut after dark. We passed by this possum that seemed to have lost its way and was hiding under a rock well above the tree line. Day 3 was our longest day. Leaving Jumbo hut at about 7am, we traversed to Mount Holdworth, then dropped down through the forest to the Mid Waohine Hut which we reached at about 11am. After a very brief dip in the river, a long and exhausting climb saw us back on the tops further to the West. From Aokaporangi Peak we headed to Maungahuka Hut which we reached about 5pm. After a short break we decided to keep going in order to be able to complete our traverse in time for work on Monday. As fast as possible we dashed over the Tararua Peaks – very steep ground which we didn’t fancy attempting in the dark. Soon we were beyond them and darkness was upon us. Four hours of arduous tramping by headtorch we arrived at Kime Hut and the end of a fifteen hour day. All that was left was to complete the Southern Crossing of the Tararuas, over Mount Hector and down the less travelled Quoine Ridge. The views in all directions were spectacular, including Taranaki and Ruapehu volcanoes, our own route through the Tararuas, the Wairarapa Plains, Palliser Bay, the Rimutaka Ranges, Wellington Harbour and the Kaikoura Ranges of the South Island. Just above the tree line we came to this GNS Science continuous GPS station cemented into the bedrock. This device is part of a nationwide network that continuously monitors the horizontal and vertical displacement of New Zealand on its plate boundary. As we descended, we entered the Goblin Forest – a wierd world of beech trees covered with mosses and lichens. Finally by 5pm we arrived at our awaiting vehicle and the prospect of a very satisfying rest.

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Marlborough and Kaikoura from the air

Yesterday I was offered a flight from Paraparaumu Airport to Kaikoura by Felix Morgenstern. His father Uwe is the water and ice dating specialist here at GNS Science. This was a great chance to admire some fantastic landforms created by the uplift of the leading edge of the Australian Tcctonic Plate right up close to the collision boundary, just east of the north end of the South Island. We flew directly south across Cook Strait, away from Wellington’s cloudy skies to a clear day over the South Island. This picture shows the coast of the Wellington Peninsula fringed by marine terraces that have been uplifted and tilted by successive earthquakes. Cook Strait is in the foreground and the white wind generator towers are making use of windy Wellington’s prime natural resource! On the other side of the Strait, the skies were clear. This is a view across the coastline to the south-east of Blenheim. The rocks that underly this landscape include several locations where the famous K-T boundary layer (Cretaceous – Tertiary or Cretaceous Paleocene boundary) is exposed. This thin dark layer of clay is found at different places worldwide. It marks the point in time when a massive asteroid impact in Mexico caused the extinction of the dinosaurs and many other life forms. One such place is the rocky hillside near to the true left of the river in the foreground. Soon we were passing alongside the inland Kaikoura Range, whose highest peak is Tapuae o Uenuku at 2,885 metres. It is made up of a complex of resistant igneous rocks, thought to be of Cretaceous age. Faults active for the last 20 million years are lined up along each side of the range, parallel to the plate boundary just off the coast. These are mainly strike slip (sideways moving) faults but there is also significant vertical movement pushing the mountains up by up to 10 mm a year. I took this picture as we were approaching the Kaikoura Peninsula. Suspended sediment in the sea from river outwash has developed into a nice spiral shaped eddy. Beyond the narrow peninsula is the area where the Hikurangi Trough meets the coast of the South Island. The Kaikoura Canyon – a deep slice in the ocean floor just off the coast, has created a haven for wildlife there including whales and other marine mammals. After landing for a short while at the Kaikoura airstrip we took a short detour out to sea. We didn’t see any whales but there was a crowd of dolphins surrounding a boat. A nice way to leave Kaikoura behind.

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