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Monday, March 14, 2011

In case you're wondering about us in Japan ....

In case you're wondering about recent events in Japan, some of cataclysmic proportion, this post may help put them in perspective.

Northern Japan is still popping, and is likely to continue to do so frequently for months if not much, much longer. The following U.S. Geological Survey sites show where, and get updated routinely:

Southern Japan is popping different ways, through active volcanoes. For instance, see: Shinmoe Dake volcano (Google Search). A brute force translation of that volcano's name is New Burning Peak. However, it's "new" relative only in human reckoning. The Pacific Ring of Fire has probably been around for 10's if not 100's of millions of years (see: USGS, This Dynamic Earth, Historical Perspective; and Age of Oceanic Lithosphere graphic, below). "About 90% of the world's earthquakes and 80% of the world's largest earthquakes occur along the Ring of Fire" (Wikipedia, Pacific Ring of Fire). Japan Meteorological Agency cameras in the Kirishima range occasionally monitor Shinmoe Dake. To see what's up, click on: 霧島山 猪子石(新燃岳),  霧島山 猪子石(御鉢), or 桜島(東郡元), near the bottom of the list at the right of the page. 

GeoDharmaYT's plate tectonics snippet from a BBC documentary (Earth: The Power of the Planet, c. Jan. 2008) illustrates the underlying mechanisms.
  • plate tectonics (YouTube, GeoDharmaYT)
    • http://www.bbc.co.uk/sn/tvradio/programmes/earthpoweroftheplanet/index.shtml
    • http://www.plymouth.ac.uk/pages/view.asp?page=33688
    • http://www.youtube.com/watch?v=ryrXAGY1dmE
If you're still wondering why shtuff like earthquakes and volcanoes happen around here, take a look at the Deep Ocean Trenches in the area around Japan, also visible on the right side of the Age of Oceanic Lithosphere graphic (by Elliot Lim, CIRES & NOAA/NGDC, based on Muller et al., 2008) below:
  • "Computerized digital images and associated databases are available from the National Geophysical Data Center, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, http://www.ngdc.noaa.gov/" (NOAA/NESDIS/NGDC/MGG-Frequently Asked Questions in Marine Geology and Geophysics).
Japan is at, near, or over convergence zones of four tectonic plates:
  1. Eurasian,
  2. Okhotsk (arguably separate from the N. Am. plate),
  3. Pacific, and
  4. Philippine.

Source: U.S. Geological Survey, Moving slabs (USGS, This Dynamic Earth, c. 2008-09)

Shtuff happens where plates converge. Large earthquakes and aftershocks can cause tsunami capable of traversing and rebounding across oceans. In short, this puts people riding the plates, especially the edges of them, at risk. I hope this makes understanding the ride, if not immediate and consequential human losses, easier.

Reference

Muller, R.D., M. Sdrolias, C. Gaina, and W.R. Roest 2008. Age, spreading rates and spreading symmetry of the world's ocean crust, Geochem. Geophys. Geosyst., 9, Q04006, doi:10.1029/2007GC001743.

1 comment:

  1. Pan due west from the starting point of the USGS Google Earth display of Earth's Tectonic Plates, and you should see not only the plates we're riding, but also locations for the "Japan Earthquake" and a M 6.1 aftershock east of northern Honshu, the long main island of Japan.

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