9.0? I guess I'm impressed...

[neomonkey]

Sorry for the facetious tone of my subject line, my intention is not to trivialize the horrors of the past week.

I have counted 5 9.0 or greater earthquakes in the past 500 years or so; an average of 1 per century, certainly rare, but considered against the lifespan of the planet, not unheard of. Scientists tell us that there are no known faults on the planet capable of quakes in the 10.0 or greater magnitude, but I find it interesting that some scientists emphasize that this only applies to single faults.

If I remember correctly, the Landers earthquake in California few years ago was actually a quake which involved more than 1 fault (a chain reaction, so to speak) and the resulting magnitude was greater than what would normally be anticipated.

What are the chances for a "super-quake" somewhere on this planet? Chile experienced a 9.6 earthquake in 1960...that's pretty damned closed to super, I would think. That quake was 60 times stronger than last week's Asian quake. Amazing, when you think about it.

[Fiona]

1. according to the USGS

there have been five 9.0 or greater earthquakes in the last 50 years.

http://earthquake.usgs.gov/docs/sign_eqs.htm

[illflem]

2. The 1960 Chile

quake liquefied the soil in the Andes, most of the fatalities were due to humongous landslides.

[HeeBGBz]

3. How about the 1811-12 New Madrid quakes

Wasn't the one that made the Mississippi flow backwards supposedly a 10? Or at least a 9?

[mcscajun]

4. There were three magnitude 8 earthquakes there that year.

http://quake.wr.usgs.gov/prepare/factsheets/NewMadrid/

[mcscajun]

5. A magnitude 10 quake is highly improbable...

"The magnitude of an earthquake is related to the length of the fault on which it occurs -- the longer the fault, the larger the earthquake. The San Andreas Fault is only 800 miles long. To generate an earthquake of 10.5 magnitude would require the rupture of a fault that is many times the length of the San Andreas Fault. No fault long enough to generate a magnitude 10.5 earthquake is known to exist. The largest earthquake ever recorded was a magnitude 9.5 on May 22, 1960 in Chile on a fault that is almost 1,000 miles long. The magnitude scale is open-ended, meaning that science has not put a limit on how strong an earthquake could be, and scientists can’t rule out a “Mega Quake” because they’ve only been measuring earthquakes for 100 years, a blink of an eye in geologic time. However, scientists agree that “Mega Quakes” of magnitude 10 or more are implausible."

http://earthquake.usgs.gov/bytopic/megaqk_facts_fantasy.html

[HeeBGBz]

6. How about quakes associated with volcanic eruptions

If there were a massive blast from a volcano would the resulting seismic events be considered an earthquake or something else? I mean eruptions are Richter scale events, aren't they?

[mcscajun]

7. An eruption may produce seismic events...but they are always separate

An earthquake is not a shock wave...but the release of friction between tectonic plates. An eruption of a volcano or other blast, or massive explosion, including a nuclear blast, will all register on seismologist's equipment. Doesn't make 'em volcanoes...or vice-versa.