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     Table 1 -  Frequency of Occurrence of Earthquakes
           Based on Observations since 1900

  Descriptor     Magnitude          Average Annually

   Great         8 and higher              1

   Major         7 - 7.9                  18

   Strong        6 - 6.9                 120

   Moderate      5 - 5.9                 800

   Light         4 - 4.9               6,200  (estimated)

   Minor         3 - 3.9              49,000  (estimated)

   Very Minor      < 3.0     2 - 3  about 1,000 per day
                             1 - 2  about 8,000 per day



     Table 2  -  Number of Earthquakes in the United States since 1900
Located by the US Geological Survey National Earthquake Information Center

                Western US       Eastern US     Alaska     Hawaii
            (excluding AK/HI)
 8 and higher       1                0             7          0
 7.0 - 7.9         18                0            84          1
 6.0 - 6.9        129                1           411         15
 5.0 - 5.9        611               41          1886         36
 4.0 - 4.9       3171              335          8362        315

Note that about 52% of all US earthquakes occur in Alaska.



     Table 3 - Number of Earthquakes Worldwide for 1982 - 1991
Located by the US Geological Survey National Earthquake Information Center

 Magnitude    1982  1983  1984  1985  1986  1987  1988  1989  1990  1991

 8.0 to 9.9      0     0     0     1     1     0     0     1     0     0
 7.0 to 7.9     10    14     8    13     5    11     8     6    12    11
 6.0 to 6.9     85   126    91   110    89   112    93    79   115   105
 5.0 to 5.9   1425  1673  1579  1674  1665  1437  1485  1444  1635  1469
 4.0 to 4.9   3232  3563  3683  4281  4476  4146  4018  4090  4493  4372
 3.0 to 3.9   1128  1578  1579  1764  1942  1806  1932  2452  2457  2952
 2.0 to 2.9    170   291   442   935  1169  1037  1479  1906  2364  2927
 1.0 to 1.9      3     8    37    97   153   102   118   418   474   801
 0.1 to 0.9      0     1     0     0     0     0     3     0     0     1
 No Magnitude 1694  2588  3074  4240  3218  2639  3575  4189  5062  3878

 Total        7747  9842 10493 13115 12718 11290 12711 14585 16612 16516

As more and more seismographs are installed in the world, more earthquakes
can be and have been located.  However, the number of large earthquakes
(magnitude 6.0 or greater) have stayed relatively constant.  Note, in fact,
that the last decade has produced substantially fewer large earthquakes
than show in the long-term averages in Table 1.



      Table 4 - Magnitude vs. Ground Motion and Energy

 Magnitude Change       Ground Motion Change    Energy Change

      1.0                      10.0  times      about 32   times
      0.5                       3.2  times      about  5.5 times
      0.3                       2.0  times      about  3   times
      0.1                       1.3  times      about  1.4 times

 This table shows, for example, that a magnitude 7.2 earthquake produces
 10 times more ground motion that a magnitude 6.2 earthquake, but it
 releases about 32 times more energy. The energy release best indicates
 the destructive power of an earthquake.

 Select Earthquake List
 Type S  for Significant Earthquakes of the World (by year)
      U  for Significant Earthquakes of the United States,
             Jan 1986 - June 1989 (132 columns)
      W  for Most Destructive Earthquakes in the World
      D  for Earthquakes with 1,000 or More Deaths in the World (from 1900)
      L  for The Ten Largest Earthquakes in the United States
      F  for Earthquake Facts and Statistics

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