Shakers Are Piling Up
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An automobile lies crushed under the third story of this apartment building in the Marina District of San Francisco. The ground levels are no longer visible because of structural failure and sinking due to liquefaction, October 17, 1989, Loma Prieta, California [J.K. Nakata, USGS] |
In the U.S., earthquakes pose significant risk to 75 million
Americans in 39 states. USGS Jan. 2004 |
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June 22, 2010 By Holly Deyo
Below is a chart I've maintained for nearly two decades showing how we fair each year with earthquakes. During the first 6 months of 2010, averages are already filling up. The largest shaker quota has already been filled. Richter 7 averages are more than 50%. Magnitude 6's and 5's are well over expectations. It's likely that this is attributable to many aftershocks from larger quakes.
Periodically quake data are "adjusted" by USGS. For example, in rechecking statistics for 2007, USGS had previously noted 5 mag. 8.0-9.9 events. Now it shows 4. When this occurs, normally the next lower Richter picks up the slack. Not this time. USGS data used to show 16 Richters 7s. That, too, was decreased by 2 events to 14. Where did these quakes go? It's pretty hard to "disappear" events of this size. Looking at the major U.S. quakes of the past 100 years, we can expect a good shake every decade. Sooner or later the U.S. can expect a mighty thump and it looks like we're due... Of the 16 events below, 11 occurred during the first 6 months of the year.
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Mag.
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2003
2004
2005
2006
2007
2008
2009
2010
USGS
Quake
Ave.
for a
Year
June 22,
2010
8.0 - 9.9
Great
0
1
2
3
1
0
2
0
4
3
1
2
1
1
4
0
1
1
1
7.0 - 7.9
Major
24
15
13
22
21
20
14
23
16
15
16
14
11
11
14
12
16
9
17
6.0 - 6.9
Strong
163
141
161
185
160
125
113
123
153
124
145
146
154
139
178
168
142
86
134
5.0 - 5.9
Moderate
1,521
1,449
1,542
1,327
1,223
1,118
979
1,106
1,345
1,243
1,252
1,637
1,954
1,529
2,072
1,768
1,700
941
1319
4.0 - 4.9
Light
5,153
5,034
4,544
8,140
8,794
7,938
7,303
7,042
8,084
8,084
8,454
10,783
13,702
13,048
12,105
12,292
6,980
4,411
13,000
Deaths
3,814
10,036
1,038
7,949
419
2,907
9,430
22,711
231
35,000-
40,000*
43,819
284,010
82,364
6,605
712
88,208
1,787
225,492
10,000
*NOTES: At the end of September 2003, the USGS adjusted earthquake global averages for magnitudes 4, 5, 6 and 7. Most have increased, one magnitude decreased in shaker averages. This indicates an overall increase in earthquake activity. To get a fair comparison, both the "old" and "new" averages are included in the chart above.
The exact number of deaths from the January 26, 2001 India earthquake will never be known. According to the Red Cross, "Death toll reports vary widely, with some ranging from more 20,000 to as many as 100,000."