Seven Point O

First, I must offer my sympathy to the people suffering in Haiti and their relatives around the world trying to find out what has happened.  This is a tragedy that all of us have to be touched by.  Second, there are organizations prepared to assist the people of Haiti, but be careful of the scammers who are sure to be soliciting money to help in the earthquake.  Give to organizations you know are good.  Charity Navigator is an online site that evaluates charitbable organizations.


The Richter Scale is not understood by many people, especially those who don't live in earthquake country.   One reporter I heard this morning was reporting aftershocks "almost as powerful as the original."  The original is being reported as 7.0.  The big aftershocks she mentioned were "as high as 5.0."

These are not even close.  Every point on the Richter Scale is TEN times higher than the previous point.  So, 6.0 is TEN times more powerful than a 5.0.  And 7.0 is then ten times ten, or, 100 times more powerful than a 5.0.  So, as I say, a 5.0 aftershock is not even close to a 7.0

I grew up in Los Angeles, and have spent most of my life in Anchorage, both in earthquake country.  The largest earthquake I've experienced was a 6.6 in LA in 1971.   In LA, there was some damage at 6.6, and in the epicenter a new hospital collapsed.  But overall things paused for a few days as schools and other buildings were inspected and then life went on.

San Francisco's 1989 Loma Prieta  earthquake "measured 6.9 on the moment magnitude scale[5] (surface-wave magnitude 7.1) or 7.0 on the open ended Richter Scale.[1]"(from Wikipedia.)  The death tool was 63.  While there was significant damage (estimated at $6 billion), it appears that the damage and death toll were significantly less than what is being reported in Haiti.  In Port Au Prince, according to the NY Times:
The earthquake, the worst in the region in more than 200 years, left the country in a shambles. As night fell in Port-au-Prince, Haiti’s capital, fires burned near the shoreline downtown, but otherwise the city fell into darkness. The electricity was out, telephones were not working and relief workers struggled to make their way through streets blocked by rubble.
In the chaos, it was not possible for officials to determine how many people had been killed and injured, but they warned that the casualties could be substantial.

A more recent story online reports "a death toll tentatively estimated by Haitian Prime Minister Jean-Max Bellerive at more than 100,000."

Wrath of God or lack of adequate building standards?

God is one of the stories people use to explain how the earth works.  "Government is evil" is another story that people use to explain things.  Another story we can use is that much of what government does is invisible and we don't notice it until it isn't working.  Zoning rules, including building standards, are often seen as one of the evils of government.  People resent government rules that say they can't build a house the way they want or that they have to use a method that will increase the costs considerably. And sometimes general rules sometimes don't make sense in specific situations and there are cases of corrupt building inspectors.

But Port-au-Prince's apparent devastation compared to San Francisco's relatively minor damage shows how science and government can set standards for construction, which, if enforced, save lives.  As individuals we are always tempted to cut corners when our dollars don't match our desires, but the law encourages us to use methods that were developed with potential disasters (fires, hurricanes, as well as earthquakes) in mind.  Again, I realize these rules are not perfect and as the science improves old methods get changed.  And humans who enforce the rules aren't necessarily consistent or honest.  But looking at the difference between the damage in Haiti in 2010 and in San Francisco shows the value good, well enforced, building codes make.   The low death toll in San Francisco is, in part, a result of one of the invisible roles government plays in our lives when it is working right. 



Here's a little more context for the Ricther Scale from the United States Geological Survey.



Richter
Approximate Magnitude
Approximate TNT for
Seismic Energy Yield
Joule equivalent
Example
0.0
1 kg (2.2 lb)
4.2 MJ

0.5
5.6 kg (12.4 lb)
23.5 MJ
Large hand grenade
1.0
32 kg (70 lb)
134.4 MJ
Construction site blast
1.5
178 kg (392 lb)
747.6 MJ
WWII conventional bombs
2.0
1 metric ton
4.2 GJ
Late WWII conventional bombs
2.5
5.6 metric tons
23.5 GJ
WWII blockbuster bomb
3.0
32 metric tons
134.4 GJ
Massive Ordnance Air Blast bomb
3.5
178 metric tons
747.6 GJ
Chernobyl nuclear disaster, 1986
4.0
1 kiloton
4.2 TJ
Small atomic bomb
4.5
5.6 kilotons
23.5 TJ

5.0
32 kilotons
134.4 TJ
Nagasaki atomic bomb (actual seismic yield was negligible since it detonated in the atmosphere)
Lincolnshire earthquake (UK), 2008
5.4
150 kilotons
625 TJ
2008 Chino Hills earthquake (Los Angeles, United States)
5.5
178 kilotons
747.6 TJ
Little Skull Mtn. earthquake (NV, USA), 1992
Alum Rock earthquake (CA, USA), 2007
6.0
1 megaton
4.2 PJ
Double Spring Flat earthquake (NV, USA), 1994
6.5
5.6 megatons
23.5 PJ
Rhodes (Greece), 2008
6.7
16.2 megatons
67.9 PJ
Northridge earthquake (CA, USA), 1994
6.9
26.8 megatons
112.2 PJ
San Francisco Bay Area earthquake (CA, USA), 1989
7.0
32 megatons
134.4 PJ
Java earthquake (Indonesia), 2009 12 January 2010 earthquake (Haiti)
7.1
50 megatons
210 PJ
Energy released is equivalent to that of Tsar Bomba, the largest thermonuclear weapon ever tested.
7.5
178 megatons
747.6 PJ
Kashmir earthquake (Pakistan), 2005
Antofagasta earthquake (Chile), 2007
7.8
600 megatons
2.4 EJ
Tangshan earthquake (China), 1976
8.0
1 gigaton
4.2 EJ
Toba eruption[citation needed] 75,000 years ago; the largest known volcanic event
San Francisco earthquake (CA, USA), 1906
Queen Charlotte earthquake (BC, Canada), 1949
México City earthquake (Mexico), 1985
Gujarat earthquake (India), 2001
Chincha Alta earthquake (Peru), 2007
Sichuan earthquake (China), 2008 (initial estimate: 7.8)
8.5
5.6 gigatons
23.5 EJ
Sumatra earthquake (Indonesia), 2007
9.0
32 gigatons
134.4 EJ
Lisbon Earthquake (Lisbon, Portugal), All Saints Day, 1755
9.1
67 gigatons
477 EJ
Indian Ocean earthquake, 2004 (40 ZJ in this case)
9.2
90.7 gigatons
379.7 EJ
Anchorage earthquake (AK, USA), 1964
9.5
178 gigatons
747.6 EJ
Valdivia earthquake (Chile), 1960 (251 ZJ in this case)
10.0
1 teraton
4.2 ZJ
Never recorded by humans.
13.0
108 megatons = 100 teratons
5x1030 ergs = 500 ZJ
Yucatán Peninsula impact (causing Chicxulub crater) 65 Ma ago.[8][9][10][11][12]