Millennium Ark: Earthquakes 1992

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%