Disaster Risk Reduction

Natural Hazards Science for East Coast Schools

Natural Hazards Activities for Schools This article is about a science education project that I was involved in that was supported by MBIE’s Unlocking Curious Minds fund in 2018. It involved four three-day natural hazards science camps for intermediate level students in New Zealand’s rural Tairawhiti (Gisborne – East Cape) region. A total of 109 year 7 and 8 students and 16 teachers, from 19 schools were represented. The science camps were based at four different locations (Gisborne, Te Karaka, Tolaga Bay and Ruatoria / Te Araroa) with the activities and field trips tailored to suit each area. The events included lots of field trips and hands-on problem solving tasks. Here for the record is a summary of some of the activities and also a few of the places we visited: Introductory activities included observation and thinking exercises around the theme of science and natural hazards. These included demonstrations such as: earthquake P (longitudinal) and S (transverse) waves using slinky springs. A TC1 seismometer was used to demonstrate how ground shaking (created by participants jumping on the floor) can be captured as a wave trace on a projector screen, giving a record of the magnitude (energy) and duration of the vibrations. The TC1 can be used by schools and individuals who wish to detect earthquakes and interact with other enthusiasts online as part of the Ru programme in New Zealand Rock deformation: Alternating layers of flour and sand in a transparent container show how rocks can be faulted and folded by compression of the earth’s crust. For information about this demonstration have a look this earthlearningidea.com page. For a bit of a hands-on problem solving challenge, participants were invited to create some model structures to protect an area fromcoastal erosion. The models were set up in shallow storage containers. Once the ‘seawalls’ were built, the area behind them was backfilled with sand, the containers tilted at a shallow angle, and water added to within about 15cm of the ‘sea wall’. Here is one example: Testing involved using a plastic lid to push the water in waves up against the seawall, first gently, then with increasing energy. Different designs could then be compared and strengths and weaknesses discussed.   Following this exercise we travelled to Wainui Beach, Gisborne where there has been a variety of attempts to protect the foredunes which have properties built on them. Interestingly, many of the methods that had been used were similar to those that the students thought of with their model making. Here you can see the remains of a concrete wall that has been undermined by wave erosion    Another similar model making exercise, this time including a slope of cardboard at one end, was to design rockfall barriers.  These were also tested to destruction using varying quantities and sizes of rocks rolled down the slope. We were also able to do another activity associated with flooding which has been a big issue this year in the Gisborne area.The photo shows the sediment covering some of the farmland near Te Karaka following the floods. For this activity, participants had to design a stop-bank, and test how long it could retain water, by recording any pooling of water on the ‘dry’ side , every 30 seconds. If you are an educator wanting information sheets to run these activities they can be found on the GNS Science website learning pages here. Here are some of the field locations that we visited, and what we investigated at them: At Pouawa Beach, north of Gisborne, we made careful drawings of some deposits that are thought to have been laid down by a tsunami. Shells in these layers have been radiocarbon dated at about 2000 years old. The layers include gravel and shells that would have been transported from the sea floor. Using a  drone we could get a good view the top of a marine terrace (the flat surface upper left of pic) at the north end of the beach. The terrace was formed at sea level as a wave-cut platform during the last interglacial (about 80 thousand years ago), and has been uplifted since its formation by tectonic activity. There is a wide shore platform which you can see just covered by water in the photo. Another great example is nearby at Tatapouri –  for more information check out the GeoTrip here – these surfaces will also be uplifted eventually to form another step in the landscape. These marine terraces show that earthquakes and tsunamis have a long history on the East Coast! At the north end of the beach. we passed a landslide that had occurred during the very wet weather in June 2018. From the ground we could see the toe of the slip which included tree trunks, boulders and lots of muddy sediment. With our drone, we were able to get a much more complete view of the slip, including the source area, which was not visible from where we were standing. This shows clearly the value of drone technology as a tool to extend our view of this active landscape: Next stop Tolaga Bay, where the beach has been covered by logs, brought down from the forestry plantations by the recent heavy rainfall. The logs caused a lot of damage to properties, bridges and land as they travelled down the flooded rivers. Here we spent some time analysing the types of logs scattered on the beach, by counting the different species (pine, poplar, willow or other) within 10m square quadrats. The results showed that by far the majority came from pine forestry. We were able to visit a forestry area inland of Tolaga Bay, which showed that following harvesting of the pine trees, there is a period of time where the land is vulnerable to erosion before the next generation forest grows large enough to stabilise the soil. Following clear-felling, the slash (abandoned logs and branches) can get washed into rivers during heavy rainfall. Further North still we did a day trip

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Lahars on Ruapehu

Ruapehu Eruption, Image: Lloyd Homer@GNS Science Ruapehu is very popular with skiers, trampers and other adventurers. As an active volcano with the potential for sudden eruptions through its crater lake, Ruapehu presents the Department of Conservation with a significant hazard management issue. Lahars on Ruapehu: Image: Lloyd Homer@GNS Science Obviously there is the possibility of people in the vicinity of the summit area being immediately affected by water, rocks and ash thrown out by an eruption. An additional hazard is that displaced water and sediment from the crater lake can mix with snow and loose volcanic material to create fast moving mudflows (lahars) which descend rapidly down valleys radiating away from the summit. The collapse of the crater wall can also cause a lahar to flow down the Whangaehu Valley to the east of Ruapehu, independently of an eruption. It was this type of lahar that caused the railway tragedy at Tangiwai in 1953. This video explains the basics of lahars at Ruapehu and the two ways they can be created: Image Graham Leonard@GNS Science Not surprisingly, due to the high number of mountain users, the lahar hazard has been studied in detail and measures put in place to give warnings and reduce the potential impact on people and infrastructure. This has involved a close collaboration between GNS Science (GeoNet), the Department of Conservation and Ruapehu Alpine Lifts who run the ski areas. First of all, regular monitoring of the crater lake’s physical and chemical properties is carried out by GNS volcanologists as part of the GeoNet project. This alerts them to changes of activity within the volcano: This information helps the GeoNet team to set the volcanic alert level for the mountain, which is important for a number of agencies such as the air industry, Regional Councils, local businesses and others. Because of the potential for some eruptions to occur with little or no warning, and the speed with which lahars travel down the slopes, there is also an Eruption Detection System (EDS) in place. This is triggered when both ground-shaking (seismic waves) and an air blast are detected within a short time of each other at a number of monitoring stations throughout the Tongariro National Park. This image shows the arrivals of volcanic earthquake tremors (top) and the air blast (bottom) of an eruption, at a station about 9 kilometres from the crater lake: You can see that there is a time lag of about 30 seconds between the onset of groundshaking and the arrival of the air blast at the same station. The EDS system has been developed by GeoNet and is unique in the world. A detected volcanic eruption will automatically set off the Lahar Warning System, consisting of loudspeakers that warn people in the ski areas to get out of valleys that could be affected, and onto high ground nearby. This video describes the system that has been set up to protect skiers on the mountain and how it is tested for its effectiveness: There is also a lot of information displayed visibly at key points in the ski areas and surrounding facilities and communities to explain the lahar hazard, and what to do or not to do if a warning alarm is sounded:

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Disaster Risk Reduction in Indonesia

GNS Science, in partnership with a team from the University Gadjah Mada (UGM) in Yogyakarta, is involved in a 5 year project to reduce the risks caused by natural disasters in Indonesia. Coastline, West Sumatra   J.Thomson@GNS Science Indonesia is a huge and very diverse country, made up of about 20 000 separate islands, with a total population of 250 000 000 people and hundreds of different local languages.  A very active plate boundary running alongside the country, along with its complex topography means that  much of Indonesia is susceptible to earthquakes, tsunamis, landslides, floods and volcanic eruptions. Population pressure forces many people to live in areas that are highly vulnerable to these hazards, such as coastlines, river banks and on the slopes of volcanoes. This small river in Palu, Sulawesi, can become a raging torrent in heavy rain. Several houses on the right bank were washed away in a flood some years ago, and yet people still live right next to the river on the opposite bank. Another disaster waiting to happen?  2004 Tsunami aftermath, G.Mackley In recent years some of the major natural disasters in Indonesia include the 2004 tsunami that devastated Banda Aceh, as well as several subsequent damaging earthquakes.  The Strengthened Indonesian Resilience – Reducing Risk from Disasters (StIRRRD) project aims to bring different agencies together in Indonesia to better prepare people and infrastructure from future such hazardous events.   Image; G. Mackley New Zealand has similar geological and environmental conditions to Indonesia, but a much smaller population. It is a much simpler matter for organisations in New Zealand to work together on common issues relating to hazards. For example science, engineering, planning, environmental management, civil defence, NGO and government agencies can share information to assist decision making processes around disaster risk reduction (DRR). This integrating capability and experience is what New Zealand can contribute to assist a larger more complex country like Indonesia in such a project. I joined the GNS Science team recently on a visit to some of the districts in Indonesia that are participating in the project. Michele Daly from GNS Science addresses a meeting in Palu. Over two weeks we travelled to Palu and Donggala (Central Sulawesi), Mataram (Lombok), and Bengkulu and Padang in West Sumatra (see project map here). We were involved in meetings and workshops with people from many agencies, and also went on several field trips to look at different environments and projects. In this video, Michele Daly from GNS Science, and Faisal Fathani from UGM, give and outline of the project:   J.Thomson @ GNS Science   Here are some images from the field trips: An active fault runs up the cliff between the brown coloured sandy rock on the left and the pale grey limestone on the right that has collapsed in a large rock fall. This is near Donggala, Central Sulawesi. J.Thomson @ GNS Science A year ago the village of Gol in Lombok was almost totally destroyed in an earthquake that lasted a few seconds. This newly rebuilt house stands next to the broken ruins of its predecessor that have yet to be cleared away. J.Thomson @ GNS Science This sea wall on the coast of North Lombok was built to protect the village next to it. Within a year of construction it was breached in a big storm and many houses were severely damaged. J.Thomson @ GNS Science This massive concrete structure being built near Bengkulu in West Sumatra is a tsunami vertical evacuation building. When completed it will be used as a community centre, with enough space and supplies on the top level for about 2000 people to escape from a tsunami at short notice. This example shows how the Indonesians are taking on significant Disaster Risk Reduction initiatives. For more information about this project and to be in touch with updates have a look at the StIRRRD Blog or ‘like’ the project on Facebook.

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“Drop, cover and hold on” is the best advice…

How to Respond to an Earthquake in New Zealand This article has been compiled by Karen Hayes at GNS Science with the help of experts including Julia Becker and David Johnston from the Joint Centre for Disaster Research at Massey University, and Adrian Prowse from the Ministry of Civil Defence and Emergency Management (now the National Emergency Management Authority). All photos are by Julian Thomson.  Information about the ‘Triangle of Life’ has been disseminated via a chain e-mail that has been in circulation since the 1990’s. The claims regarding the “Triangle of Life” earthquake response are widely discounted. The “Triangle of Life” is not an advocated approach to responding to earthquakes and has been internationally dispelled as being unsound practice. In modern countries such as New Zealand, most buildings are constructed well and you are more at risk of getting hurt from objects flying around rooms. Therefore people should “drop, cover and hold on” in an earthquake. The New Zealand Ministry of Civil Defence and Emergency Management includes the recommended “drop, cover and hold on” advice on their webpage that you can download:  I recommend you print the fact sheet and stick it on your fridge to remind yourself and your family of how best to respond in an earthquake.    Let’s just take a quick moment to consider one of the claims in the “Triangle of Life” chain e-mail. It states that children have been killed in past earthquakes because they were under their school desks and these were flattened when the building collapsed. It states that they would have been safe had they been lying beside the desk, instead of under it, where a supposed ‘void space’ should be. Realistically speaking, if the desk was not substantial enough to protect the child under it and was flattened by the collapse of a building, then any void space wouldn’t have been large enough to protect the child lying on the floor next to it either. A child is better off getting under the desk to prevent them from being struck by falling items. In the Christchurch earthquake on 22 February 2011, when children did “drop, cover and hold on” under desks, there were no significant injuries reported from any school in the Christchurch area. Building codes designed to reduce earthquake risk will ensure that buildings are unlikely to collapse in the first place. Why Rescuers and Experts Recommend Drop, Cover, and Hold On (the following is taken directly from the earthquakecountry website) Trying to move during shaking puts you at risk: Earthquakes occur without warning and may be so violent that you cannot run or crawl; you therefore will most likely be knocked to the ground where you happen to be. On that basis, it is best to drop before the earthquake drops you, and find nearby shelter or use your arms and hands to protect your head and neck. “Drop, cover, and hold on” gives you the best overall chance of quickly protecting yourself during an earthquake… even during quakes that cause furniture to move about rooms and even in buildings that might ultimately collapse. The greatest danger is from falling and flying objects: Studies of injuries and deaths caused by earthquakes over the last several decades show that you are much more likely to be injured by falling or flying objects (TVs, lamps, glass, bookcases, falling masonry, etc) than to die in a collapsed building. “Drop, cover, and hold on” (as described above) will protect you from most of these injuries. If there is no furniture nearby, you can still reduce the chance of injury from falling objects by getting down next to an interior wall and covering your head and neck with your arms (exterior walls are more likely to collapse and have windows that may break). If you are in bed, the best thing is to stay there and cover your head with a pillow. Studies of injuries in earthquakes show that people who moved from their beds would not have been injured had they remained in bed. You can also reduce your chance of injury or damage to your belongings by securing them in the first place. Secure top heavy furniture to walls with flexible straps. Use earthquake putty or velcro fasteners for objects on tables, shelves, or other furniture. Install safety latches on cabinets to keep them closed.   Building collapse is less of a danger: While images of collapsed structures in earthquakes around the world are frightening and get the most media attention, most buildings do not collapse at all and few collapse completely. In earthquake-prone areas of New Zealand, as in many other countries, strict building codes have worked to greatly reduce the potential of structure collapse. However, there is the possibility of structural failure in certain building types, especially unreinforced masonry (brick buildings) and in certain structures constructed before the latest building codes. Rescue professionals are trained to understand how these structures collapse in order to identify potential locations of survivors within “survivable void spaces”. The main goal of “drop, cover, and hold on” is to protect you from falling and flying debris and other non-structural hazards, and to increase the chance of your ending up in a “survivable void space” if the building actually collapses. The space under a sturdy table or desk is likely to remain even if the building collapses – pictures from around the world show tables and desks standing with rubble all around them and even holding up floors that have collapsed. Experienced rescuers agree that successfully predicting other safe locations in advance is nearly impossible as where these voids will be depends on the direction of the shaking and many other factors. If you receive the email in future…If you receive the “Triangle of Life” email, you should reply to the sender and let them know the advice is wrong, and point them in the direction of correct information about how and why to “drop cover and hold on”! Summary:     Do: • Identify safe places at home and

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