Tectonics and Geo-Hazards

I found this following article from the USGS. It’s from 1999 but still interesting and there were a few things I learned.

https://pubs.usgs.gov/gip/dynamic/tectonics.html

Three interesting things I found:

  1. Many people believe that the next earthquake on the San Andreas Fault will cause part of California to sink into the ocean or split off into an island or something else ridiculous. But, this region is only a strike-slip boundary. I didn’t realize though that the fault only penetrates 15km through the crust here. I would have thought, since it’s a boundary between two plates, this fault would extend all the way through the lithosphere. Perhaps its too ductile below this point and the plate boundary becomes less defined.
  2. Tsunamis are commonly generated by earthquakes along subduction zones. Caused by the seismic displacement of water, they can travel as fast a jetliner at around 800km per hour! Volcanic eruptions in areas like subduction zones can also cause tsunamis as in the case of Krakatau in 1883. The tsunami the eruption caused alone killed more than 36,000 people and reached 7000km away.
  3. Volcanoes (a common feature along subduction zones and divergent boundaries) are responsible for nearly 300,000 deaths since 1600. They can also have global impacts on climate. The 1991 eruption of Mount Pintubo cooled some areas by up to .5 degrees C due to the large volume of material delivered into the atmosphere. In 1815, Indonesia’s Tambora volcano caused a 3 degree drop in global temperature.

 

2 thoughts on “Tectonics and Geo-Hazards”

  1. An interesting read 🙂
    I learned that the east coast of the US has earthquakes even though it is not near a plate boundary. The current thought is that it is a result from the break up of Pangaea and the westward movement of the North American Plate away from the Mid-Atlantic Ridge.

  2. Growing up in California, I was subjected to the false “falling into the ocean” narrative pretty often. It’s a little disheartening, but I think most people took it more as a joke (at least I hope so!).

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