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The Great Rift Expansion Zones
Formerly called Mid-Oceanic Ridges in the
Arctic, Atlantic, Pacific, and Indian Oceans.
The graphs for the Great Rift zones are arranged o
horizontal level. Since the volume of quakes which are being reported in most of the oceanic rifts under 4.0 is relatively small, it does not make much sense to detail the various magnitudes in most cases. The one exception is the North Atlantic, which appears to be very well recorded. Accordingly most zones are reported on this page for quakes 4+ only. xxx edit But since the North Atlantic is so well recorded, a separate webpage houses a number of graphs on a distinct Storyboard for the North Atlantic.
Major Observations:
Table of Contents for the Great Rifts
Storyboards for the Great Expansion Rifts Graphs &
Images In The Great Rifts Storyboard Great Rifts 4+
Great Rifts 2+
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Storyboard For The Great Expansion Rifts
Atlantic Great
Rift Total 4+ 1973-2007
This chart shows strong growth curve, highly variable annual deviations, STRONG connection with the rhythm of the changing size of Earth's Wobble (the seven year Chandler Amplitude cycle), and strong parallel with the trend lines of the Eurasian and West Pacific Compression Zones. There is, however, not much parallel with North America. Note the close correlation in 1982/83 and 1994/95 between the rise in earthquake activity and the expansion of the size of the Wobble.. These years began or were peak levels of activity in nearly all portions of the Earth.
Arctic
Expansion Zone 4+ 1973-2007
Not much measurable or recorded activity in the Artic, to our great impoverishment. Still, a growth can be seen, though the level of activity is so low that this could easily be written off as report inflation. There is a slight tendency to parallel other regions but it is not worth writing home about, except to note that the Arctic clearly reflected the two most recent Wobble X Min periods of 1999 and 2005/06. Major increases in earthquake activity were seen during one or both of these periods in many areas, including the North Atlantic below.
North Atlantic Expansion Zone 4+ 1973-2007
This chart is virtually identical to the chart for the entire Atlantic + Arctic because most of the recorded activity is only in the North Atlantic. Since there is virtually no increase in the Artic nor the South Atlantic, most of the growth is occuring here in the North Atlantic. It is about a three-fold increase during the past 33 years since 1973.
South Atlantic Expansion Zone
4+ 1973-2007
Apparently the South Atlantic is not expanding at nearly the rate of the North Atlantic. Most likely the differential is in the range of 0.3 - 0.5, one third to one half. Isn't this an important clue for plate tectonics specialists? Is this why there are so few quakes currently recorded in most of Africa and why volcanism in Africa has been at much lower level during the past 100 years than in Central America, Latin America, and the West Pacific? There may be a substantial "report shortage" problem for the South Atlantic.
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quakes4+_daily_world_1973-2007_expand
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Copyright 2007, MWM, all rights reserved
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