Tectonic Plates and Earthquakes
Ranging from catastrophically destructive to almost unnoticeable are the sudden tremors of the ground which we call earthquakes. Earthquakes are the result of a break in a fault under the Earth’s surface causing a releases seismic waves. Faults are fractures in the Earth’s crust, the boundaries of tectonic plates being one type of fault. Faults are also able to form away from plate boundaries due to factors such as volcanic activity, hot spots in the mantle and interaction between plates. Within faults, tension is created when the movement of rock is halted or stalled. When the tension is too great, the fault snaps, releasing energy in the form of seismic waves. These waves spread out in a circular pattern which causes the rock of the surrounding the fault to tremor. Earthquakes generally arise along the boundaries of tectonic plates as these boundaries because more faults are able to form along these lines due to the activity of plate tectonics as well as the fact that these boundaries are already existing faults. Earthquakes are still able to occur far from tectonic plate boundaries as they are able the develop at any fault on the planet. |
Developments in Technology and Understand of Earthquakes in the Asia-Pacific Region
Although we attribute our understanding of earthquakes to the research of the past few centuries, the first earthquake-detecting seismoscope was created in China by the inventor Zhang Heng in 132 BCE. The seismoscope, named the Houfeng didong yi, was a large barrel shaped object with eight arms that held eight bronze balls, each pointing in the primary compass positions. Although the mechanism is unknown, it is known that seismic waves of an earthquakes would cause a ball to fall indicating the direction the waves were travelling. Earthquakes could be detected for the first time, marking the beginning of our quest to understand these events. Between the nineteenth and twentieth centuries seismometers were created to record the seismic waves which generate earthquakes. Seismometers then evolved from using swinging pendulums containing tracing pens to using electromagnets. Modern seismometers use magnets wrapped with wire. The fluctuations of the magnets create electric signals which flow through the wires and these fluctuations are then recorded. These seismometers are placed in many corners of the globe. This advancement in these instruments allowed earthquakes to be measured and positioned accurately. World War II saw huge advancements in radar technology due to its development and use in warfare. Radar detects shapes, sizes, distances using radio waves and the great development this technology allowed scientist to accurately map out the seafloor for the first time. Great rifts and mountain ranges were discovered to be on the ocean floor. These rifts and mountain ranges were later discovered to be the boundaries between tectonic plates. The advancements in seismographs allowed scientist to map out the locations of earthquakes and although earthquakes are able to occur at any fault on the Earth, it was discovered that earthquakes were concentrated in particular areas. The majority of earthquakes occurred along tectonic plate boundaries and roughly 90% of all earthquakes occurred along a chain of plate boundaries in the Asia-Pacific region. This horseshoe shaped series of seismic activity was called The Pacific Ring of Fire. With these findings in mind, scientist concluded that most earthquakes occur along plate boundaries due to the large concentration of faults along plate boundaries, created by the interactions of plate tectonics. It was then discovered that the Ring of Fire is host to approximately 90% of all earthquakes because the Ring of Fire is the main boundary of half of the world’s tectonic plates, therefore being the host of most of the world’s seismic activity and explaining the large concentrations of earthquakes in the Asia-Pacific region. |
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References
- Rickard, G. (2011) Pearson science 9 student book. Frenchs Forest, NSW, Australia: Pearson Education Australia.
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- National Geographic (2011) Earthquakes 101. Available at: https://www.youtube.com/watch?v=VSgB1IWr6O4 (Accessed: 14 August 2016).
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- Zhang Heng and the Seismometer (no date) Available at: http://seismoscope.allshookup.org/ (Accessed: 17 August 2016).
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- Williams, M. (2015) What is the pacific ‘ring of fire’? Available at: http://www.universetoday.com/59341/pacific-ring-of-fire/# (Accessed: 17 August 2016).
- Rickard, G. (2011) Pearson science 9 student book. Frenchs Forest, NSW, Australia: Pearson Education Australia.
- Developing the theory [This dynamic earth, USGS] (no date) Available at: http://pubs.usgs.gov/gip/dynamic/developing.html (Accessed: 17 August 2016)
- SciShow (2014) Earthquake science, and the disaster that created it. Available at: https://www.youtube.com/watch?v=XOCxNVDiOnE (Accessed: 14 August 2016).
- National Geographic (2011) Earthquakes 101. Available at: https://www.youtube.com/watch?v=VSgB1IWr6O4 (Accessed: 14 August 2016).
- Cluff, L. (2014) What causes an earthquake? Faults explained. Available at: http://news.nationalgeographic.com/news/2014/01/140115-earthquakes-california-faults-science/ (Accessed: 16 August 2016).
- Endsley, K. (2007) Where do earthquakes happen? Available at: http://www.geo.mtu.edu/UPSeis/where.html (Accessed: 16 August 2016).
- History of Seismology (no date) Available at: https://www.preceden.com/timelines/40027-history-of-seismology (Accessed: 17 August 2016).
- Zhang Heng and the Seismometer (no date) Available at: http://seismoscope.allshookup.org/ (Accessed: 17 August 2016).
- Szczepanski, K. (2015) The invention of the Seismoscope. Available at: http://asianhistory.about.com/od/asianinventions/a/SeismoInvention.htm (Accessed: 17 August 2016).
- How seismographs work (no date) Available at: http://www.livescience.com/6210-seismographs-work.html (Accessed: 17 August 2016).
- Radar (no date) Available at: http://Comments(2014) Available at: http://www.engineersgarage.com/articles/what-is-radar-technology (Accessed: 17 August 2016)
- Society, N.G. (2015) Ring of fire. Available at: http://nationalgeographic.org/encyclopedia/ring-fire/ (Accessed: 17 August 2016).
- Williams, M. (2015) What is the pacific ‘ring of fire’? Available at: http://www.universetoday.com/59341/pacific-ring-of-fire/# (Accessed: 17 August 2016).