Shakers Piling Up
Aerial view of collapsed sections of the Cypress viaduct of I-880, October 17, 1989, Loma Prieta, California [H.G. Wilshire, USGS]


In the U.S., earthquakes pose significant risk to 75 million
Americans in 39 states.
USGS Jan. 2004


March 12, 2010
By Holly Deyo


Below is a chart I've maintained for nearly two decades just to see how we fair each year with earthquakes. First, I apologize to those with small monitors that will need to scroll to view the chart. It's necessary for you to see each year's info so you see the big uptick in both quakes and resulting deaths for 2010. In just 10 weeks of 2010, averages are already filling up. The largest mag. shaker quota has already been fulfilled.

It's interesting to see how quake data are periodically "adjusted" by USGS. For example, in rechecking the figures 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. Anyway, that year has passed and 2010 is already showing a remarkable number of earthquakes.

In case the explanation is unclear how to read the old and new quake averages, look at the two green columns. In 2003 USGS changed what they observed to be the average number of quakes for each magnitude. However, it's interesting to see how a year's quakes stack up to the old averages noted in purple.

It's not too concerning that USGS so drastically adjusted Richter 4s and 5s. Several factors can account for increased numbers of quakes detected under Richter 6: 
  • a greater number of actual monitors installed pick up more events and
  • more sensitive equipment give more info.

You'll get a much more accurate read with mag. 6's and greater events because even distant monitors pick up this activity. They make it harder for USGS to "disappear" like they did with the possible 8.6 quake in China this January.

Looking at the major U.S. quakes over the past 100 years, on average 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...

Nov 3, 2002A 7.9 magnitude quake centred on a sparsely populated area south of Fairbanks, Alaska was felt from the Arctic Circle to the Gulf of Mexico. It appears to have caused remarkably little serious damage and only minor injuries.

Feb. 28, 2001 – A 6.8-magnitude earthquake southwest of Seattle damages the Washington state capitol, briefly closes Seattle-Tacoma International Airport.

Oct. 16, 1999 – A 7.0-magnitude earthquake in California's Mojave Desert
derails an Amtrak train, knocks out power to thousands but causes no serious damage or injuries.

Jan 17, 1994 – A magnitude 6.7 quake in Northridge, California, in the San Fernando Valley in northern Los Angeles killed 60 people, injured more than 7,000, left 20,000 homeless and damaged more than 40,000 buildings. It collapsed overpasses, closing sections of four major area freeways. Damage estimates ranged from $13 billion and $30 billion.

June 28, 1992 – A magnitude 7.3 quake in Landers, California near Yucca Valley in the Mojave Desert killed one person and injured 400. It was felt throughout the Southwest.

Oct 17, 1989 – A magnitude 6.9 quake in the Santa Cruz Mountains near the Loma Prieta Mountains in northern California killed 63 people, caused 3,757 injuries and an estimated $6 billion in property damage. The most severe damage occurred in Oakland and San Francisco about 60 miles north, where several sections of major freeways collapsed.

Feb 9, 1971 – A magnitude 6.6 quake struck in a sparsely populated area of the San Gabriel Mountains in Southern California. It killed 65 people, injured more than 2,000 and caused property damage estimated at more than $505 million.

March 28, 1964 – Alaska - A powerful 9.2 earthquake and ensuing tsunami claimed 128 lives and caused about $311 million in property losses.

Aug 18, 1959 – The largest earthquake to hit Montana in recorded history, it measured 7.3, caused 28 fatalities and caused about $11 million in damage to highways and timber.

March 9, 1957 – An earthquake measuring 9.1 hit the Andreanof Islands of Alaska. On Umnak Island, Mount Vsevidof erupted after being dormant for 200 years, generating a 50-foot(15-metre)-high tsunami that continued to Hawaii.

July 21, 1952 – A 7.3 magnitude temblor killed 12 people and caused $60 million in damage, much of it around Bakersfield, California.

April 13, 1949 – A magnitude 7.1 quake near Olympia, Wash., kills 8.

April 1, 1946 – A magnitude 8.1 quake struck Unimak Island in Alaska, where it caused only minor damage to buildings, but generated a 115-foot(35-metre)-high tsunami that destroyed the island's lighthouse and swept away its five occupants. The tsunami killed 159 people in Hilo, Hawaii where it caused $26 million in damage, and killed one person in California. (source: AP & reuters)

March 10, 1933 – A 6.3-magnitude quake in Long Beach, Calif., kills 115 people.

April 18-19, 1906 – A 7.8 (estimated) earthquake and fires level San Francisco, killing an estimated 700 people.



GLOBAL EARTHQUAKES JANUARY 1, 1992 - MARCH 11, 2010

Mag. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
2002
2003 2004 2005 2006 2007 2008 2009 2010 New
Yearly
Ave.
Thru
Mar 11,
2010
to New
Ave.
Old
Yearly
Ave.
Thru
Mar 11,
2010
to Old
Ave.
8.0 - 9.9
Great
0 1 2 3 1 0 2 0 4 3
1
1 2 1 1 4 0 1 1 11
100%
2 50%
7.0 - 7.9
Major
24 15 13 22 21 20 14 23 16 15
12
16 14 11 11 14 12 16 3 172
12%
18 11%
6.0 - 6.9
Strong
163 141 161 185 160 125 113 123 153 124
130
145 146 154 139 178 168 142 41 1342
13%
120 15%
5.0 - 5.9
Moderate
1,521 1,449 1,542 1,327 1,223 1,118 979 1,106 1,345 1,243
1,218
1,252 1,637 1,954 1,529 2,072 1,768 1,700 476 13192
36%
800 59%
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
8,584
8,454 10,783 13,702 13,048 12,105 12,292 6,980 1,110 13,000
8.5%
6200 18%
Deaths 3,814 10,036 1,038 7,949 419 2,907 9,430 22,711 231 35,000-
40,000*
1,712
43,819 284,010 82,364 6,605 712 88,208 1,787 223,161 10,000
2200%
10,000 2200%

1 Based on observations since 1900.
2 Based on observations since 1990.

*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."