New Zealand, The Most Dangerous Hazard

New Zealand is a beautiful place, full of unique qualities that no other place on earth can match. However, it also unmatched in seismic activity, with only a few other places on earth reporting close to the same numbers. This is because the country lies on two tectonic plates, the northern island rests on the Pacific plate, also known as the Pacific Ring of Fire, and the southern island rests on the Indo-Australian plate. These two plate boundaries are convergent plate boundaries, “where one plate dives beneath another or two collide” (Keller and DeVecchio 48). The image shows the Pacific plate diving under the Indo-Australian plate just below the northern island (indicated by bold arrows pointing northwest, dividing the two plates), where the subduction changes directions. Following the Marlborough fault system and the Alpine fault, the Indo-Australian plate begins to sink below the Pacific plate (indicated by bold arrows pointing south-west).

These fault systems are what links these two plates together. The high-risk areas are those that skirt the fault lines, which almost split the islands down the middle. The farther away from the fault lines the least likely the area is to receive seismic activity. With that being said, the safest place to build a house, thereby having the best chance at avoiding an earthquake is on the north island, north of Auckland. The farther north and away from the plate boundaries and the fault lines the safer the area.

It is important to note a single earthquake does not accurately represent the seismic activity common in the region. Since the early 1900’s, there have been 15 other M7.5+ earthquakes, making the Indo-Australian plate one of the most seismically active in the world. When scaling back and looking at the total amount of earthquakes it becomes clear the majority have a relatively small magnitude; with more shallow seismic activity occurring compared to deeper activity. The below live map covers the last 12 years of seismic activity, and its clear to see why this hazard needs to be mitigated. An earthquake can cause side effects like landslides, tsunamis, etc. These hazards have almost become a part of life for any of those living in the country, that being said, New Zealand has taken many proactive measures to ensure preparedness.

First is the number of seismographs placed to detect an event. Second, the government has passed legislation that requires buildings be up to a certain standard, ensuring that when an earthquake does occur it would cause minimal damage. Long term projections of plate movements can also help prepare those native to the region. The most helpful of all is community outreach. There are numerous apps, websites, and other local forums that help inform the community and provide information on who is most at risk and what should be done in during an event. On top of what is already in place, I would recommend updating the seismographs to link to an app. That way if there is an earthquake in the area it will send users information on the earthquake and what should be done if anything. Some might be so small that changing the daily routine might not be necessary.

Sources: 

https://www.stuff.co.nz/national/100611311/heres-what-a-decade-of-nz-quakes-looks-like-in-20-seconds

http://www.legislation.govt.nz/regulation/public/2005/0032/latest/DLM313976.html?search=ts_regulation_building_resel&p=1.

http://www.seismicresilience.org.nz/topics/seismic-science-and-site-influences/seismicity-in-new-zealand/.

https://www.otago.ac.nz/geology/research/structural-geology/alpine-fault/nz-tectonics.html

Keller, A. Edward, and Duane E. DeVecchio. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. 4th ed., Pearson Education, 2015. Print.

New Zealand's Coastal Hazards

Coastal hazards can be broken up into a few different categories, global warming contributing to rising sea levels, strong coastal currents such as rip currents, coastal erosion, storm surges from extra-tropical cyclones (which are more common in New Zealand), and tsunamis.

New Zealand focuses on preventing a wide range of coastal hazards through the holistic approach of knowing "hazard exposure." Achieved through, numerical and field studies, statistical analysis of extreme hazard magnitudes and post-event surveys following a damaging event, supported through monitoring of camera networks to measure tides, sea level, tsunami, coastal erosion, waves, winds, and surf conditions.

The information received is then input into a computer modeling system, which helps with predictive modeling done by the National Institute of Water and Atmospheric Research (NIWA); once the information has been vetted the maps are used in Riskscape to show present and future risk. This information is widely used and distributed throughout the population, helping coastal planning and guidance for government, improving New Zealand's ability to reduce the risk of a potential coastal hazard and response time.













Sources: https://www.niwa.co.nz/natural-hazards/hazards/coastal-hazards

Extreme Weather in New Zealand

New Zealand is known for being a place of extremes, earthquakes, tsunamis, volcanic activity, and weather. Meteorologists have identified a trend in weather patterns, like the rest of the earth, climate change is affecting New Zealand. With already considerably high rainfall, experts have found a steady increase in rain and expect to continue to see it climb. The same is expected in the dry season, in fact, last year New Zealand had its fifth hottest recorded year in a century. All five of which occurred in the previous twenty years. The extremism doesn't stop there, a total of 173,000 lightning strikes were recorded in 2017. While these conditions seem harsh, technology has made them bearable, there are numerous websites and live feeds that help those in the area, and those wanting to visit, prepare for and potentially avoid the extreme weather New Zealand has to offer.

Sources:

https://www.sciencemediacentre.co.nz/2018/01/08/2017-year-extreme-weather-expert-reaction/

Mass Wasting, a Slippery Slope

     

     

     New Zealand, is located on multiple faults, which means that its land mass is continuously changing and shifting, ranging from a few millimeters to inches. Some of these changes occur over years, and others happen within a few minutes. Because of the variability, with earthquakes, faulting, volcanic activity, and weather, landslide activity is frequent when compared to other countries. All of these things can play a factor when thinking of landslides, though not the causes themselves, for example, if a slope is formed on weak layers of volcanic ash, then it is far less stable and is likely to produce a mass movement.

      Many different types of landslides can affect New Zealand, including, alpine slides, low mountain landslides, layered rock landslides, rotational landslides, creeping earth flows, regolith landslides, and submarine landslides. While these all seem daunting, making life on this tiny country unfeasible, the mortality rate caused by landslides is lower than most countries for a few different reasons. The first is relatively obvious; there are not a lot of people living in high-risk areas. The second reason is preparation, through technological advances seismic sensors are scattered throughout the islands and can identify when the chances of a landslide are increased and send alerts to the at-risk communities. Probably the most critical factor in New Zealand's low mortality rate with an unpredictable landscape is working proactively, instead of reacting to a disaster.


Sources:
https://www.gns.cri.nz/Home/Our-Science/Natural-Hazards/Landslides
http://www.learnz.org.nz/geohazards152/landslides-in-new-zealand

New Zealand Volcanic Activity

New Zealand is pretty much just a giant volcano. I say that because in total there are 345 volcano's as reported by the Smithsonian Institution National Museum of Natural History Global Volcanism Program. There are so many in the area because of the type of plate boundary New Zealand lies on, which is a convergent subduction plate as I have stated in previous blog posts. Keep in mind the majority of these volcano's are not active and are submerged underwater, but even on the islands, there are quite a few. The Active and potentially active volcano's are permanently monitored 24/7; using techniques in geodesy, seismology, chemistry, and remote sensing. There are early volcanic unrest monitor systems in place that monitor seismic activity and early gas release. Another helpful tool used is volcanic hazard maps that show the vulnerability of areas to lava flows, pyroclastic flows, and ash fall, which would look something like the picture provided. On top of that, there is a lot of community outreach and crowd sourcing to notify those in danger.  Also, eruption scenarios are held for risk assessment and preparedness. 

Sources: 

https://www.gns.cri.nz/Home/Our-Science/Natural-Hazards/Volcanoes

http://volcano.si.edu/database/search_volcano_results.cfm

New Zealand's Seismology

      New Zealand is on the intersection where the subduction between the Indo-Australian plate and Pacific plate occur which makes for frequent seismic activity. Just the other day there was an earthquake 96 km off the coast recorded at a 5.0 magnitude. A single earthquake does not accurately represent the seismic activity common in the region. Since the early 1900’s, there have been 15 other M7.5+ earthquakes, making the Indo-Australian plate one of the most seismically active in the world. When scaling back and looking at the total amount of earthquakes it becomes clear the majority have a relatively small magnitude; with more shallow seismic activity occurring compared to deeper activity. The following maps show the past ten years of shallow and deep earthquakes.

              

       However, this is not to say that New Zealand is less susceptible to large-scale events. On November 14, 2016, a recorded 7.8 was felt throughout the entire country and is described as one of the largest, most complex earthquakes ever recorded with modern technology. What made it complicated and unusual was the fact it traveled through 12 major crustal faults. It was the most powerful seismic event occurring in New Zealand in over 150 years which “resulted in surface slip of more than 10 m along multiple faults, several of which were previously unmapped or considered inactive, despite New Zealand having one of the most accurate and comprehensive maps of active faulting worldwide” (Hamling et al. 1). Because earthquakes are a frequent part of life for any of those living in the country, New Zealand has taken many proactive measures to ensure preparedness. The below map shows the location of seismographs the country has for early detection and prediction. The country has also passed legislation requiring buildings to be up to code a structurally sound to survive frequent seismic activity as well as offering numerous websites that inform and prepare the population for earthquakes, eruptions, and tsunamis.

Works Cited 

“Building (Specified Systems, Change the Use, and Earthquake-prone Buildings) Regulations 2005.” Parliamentary counsel office, http://www.legislation.govt.nz/regulation/public/2005/0032/latest/DLM313976.html?search=ts_regulation_building_resel&p=1. Accessed 6 September 2018.

Hamling, Ian J, et al. "Complex Multifault Rupture during the 2016 Mw 7.8 Kaikōura Earthquake, New Zealand." Science (New York, N.Y.), vol. 356, no. 6334, 14 Apr. 2017. EBSCOhost, doi:10.1126/science.aam7194. 

“Seismicity in New Zealand.” Branz, http://www.seismicresilience.org.nz/topics/seismic-science-and-site-influences/seismicity-in-new-zealand/. Accessed 6 September 2018.

Seismological Society of America. "Seismologists offer detailed look at New Zealand's Kaikoura earthquake." ScienceDaily. ScienceDaily, 12 April 2017. <www.sciencedaily.com/releases/2017/04/170412111125.htm>. Accessed 6 September 2018.

New Zealand Tectonic Placement, Two Plates are Better Than One

                                                                                                             

     New Zealand lies on two tectonic plates, the northern island rests on the Pacific plate, also known as the Pacific Ring of Fire, and the southern island rests on the Indo-Australian plate. These two plate boundaries are convergent plate boundaries, “where one plate dives beneath another or two collide” (Keller and DeVecchio 48). The image shows the Pacific plate diving under the Indo-Australian plate just below the northern island (indicated by bold arrows pointing northwest, dividing the two plates), where the subduction changes directions. Following the Marlborough fault system and the Alpine fault, the Indo-Australian plate begins to sink below the Pacific plate (indicated by bold arrows pointing south-west). These fault systems are what links these two plates together. The Marlborough fault system moves the northern part of the country laterally across the southern part, while the Alpine fault not only laterally moves the plates but brings them closer together each year; causing the Southern Alps to raise at a rate of approximately seven millimeters per year (“Tectonic Setting of New Zealand”). The constant activity of two converging tectonic plates makes New Zealand prone to many natural hazards including frequent seismic activity and reoccurring volcanic eruptions.

Works Cited

Keller, A. Edward, and Duane E. DeVecchio. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. 4th ed., Pearson Education, 2015. Print. Accessed 31 August 2018.

Lewis, Ian D. "'Australia on a Plate' - Volcanoes on Land and around Our Edge." Geodate, vol. 27, no. 4, Aug. 2014, p. 6. https://libproxy.mpc.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=f6h&AN=97912553&site=eds-live&scope=site. Accessed 31 August 2018.

“Tectonic Setting of New Zealand.” University of Otago, https://www.otago.ac.nz/geology/research/structural-geology/alpine-fault/nz-tectonics.html. Accessed 31 August 2018.