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.

Natural Hazards, Disasters, and Catastrophes

      After beginning the first chapter of Pearson's Natural Hazards, Earths Processes as Hazards, Disasters, and Catastrophes 4th ed., (2015), by Edward A. Keller and Duane E. DeVecchico it became clear devastating events which happen worldwide such as earthquakes, volcanic eruptions, landslides, and flooding are normal. These events that can affect countless people are simply Earth's natural processes which are defined as "physical, chemical, and biological ways by which events, such as volcanic eruptions, earthquakes, landslides, and floods affect Earth's surface" (Keller and DeVecchio 5). These processes are broken up into two specifications internal, and external, which depending on the potential threat is classified as either a hazard, disaster, or catastrophe.  A natural hazard "is a natural process and event that is a potential threat to human life and property" (Keller and DeVecchio 5). Earth's natural processes are not a hazard themselves but become so when people use the land that is affected. Next, a natural disaster "is a hazardous event that occurs over a limited time span within a defined area. Criteria for a natural disaster are (1) 10 or more people are killed, (2) 100 or more people are affected, (3) a state of emergency is declared, and (4) international assistance is requested" (Keller and DeVecchio 5). If any of the preceding criteria are met, whether it be caused by an earthquake, flood, or hurricane, then the event would be classified as a natural disaster. Finally, the largest and most worrisome event is a natural catastrophe which "is a massive disaster that requires significant expenditure of money and a long time (often years) for recovery to take place" (Keller and DeVecchio 5). These three terms are used to describe human interaction with the natural processes of Earth, and while some areas are more prone to being affected by a natural hazard than others, no place is considered risk free.

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 23 August 2018.