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The earthquake, which measured 6.1 on the moment magnitude scale[1] (equivalent to 6.9 on the Richter scale)[7][6], occurred on July 26, 1963 at 4:17 am UTC[2] (5:17 am local time)[6][3] in Skopje, Socialist Republic of Macedonia, then part of SFR Yugoslavia (present-day Republic of Macedonia). The tremor lasted for 20 seconds[6][7] and was felt mostly along the Vardar River Valley[7]. There were also smaller aftershocks until 5:43.[8]
Date 00:58:53, December 26, 2004 (UTC)
Magnitude 9.1–9.3 Mw
Depth 30 km (19 mi)
the recent increase in major earthquakes, which are defined as above 6 on the Richter magnitude scale. Japan's earthquake was a 9.0.
Scientists have been tracking these powerful quakes for well over a century and it's unlikely that they have missed any during at least the last 60 years.
The U.S. Geological Survey says there were 1,085 major earthquakes in the 1980s. This increased in the 1990s by about 50 per cent to 1,492 and to 1,611 from 2000 to 2009. Last year, and up to and including the Japanese quake, there were 247 major earthquakes.
There has been also a noticeable increase in the sort of extreme quakes that hit Japan. In the 1980s, there were four mega-quakes, six in the 1990s and 13 in the last decade. So far this decade there have been two. This increase, however, could be temporary.
Originally posted by PuterMan
reply to post by soficrow
Sorry but I have to go to bed as it is 4am.
I will rip that stupid article to pieces tomorrow if you really want me to.
Just consider this however - how can the number of earthquakes matter when the energy is logarithmic?
A 6 is 63 Terajoules, a 7 is 1995 Terajoules. How does it make sense to count them as numbers?
Severe earthquakes in Haiti, Chile and now Japan have experts around the world asking whether the world's tectonic plates are becoming more active -and what could be causing it.
Some scientists theorize that the sudden melting of glaciers due to man-made climate change is lightening the load on the Earth's surface, allowing its mantle to rebound upwards and causing plates to become unstuck.
These scientists point to the historical increase in volcanic and earthquake activity that occurred about 12,000 years ago when the glaciers that covered most of Canada in an ice sheet several kilometres thick suddenly melted.
The result was that most of Canada's crust lifted -and is still rising.
Scientists have discovered that the accelerated melting of the Greenland ice sheet over the last 10 years already is lifting the southeastern part of that island several millimetres every year.
Other scientists, however, believe tectonic movements similar to the one that caused the Japanese quake are too deep in the Earth to be affected by the pressure releases caused by glacier melt.
These scientists theorize that glacier melts could cause shallower quakes.
Andrew Hynes, a tectonics expert at Montreal's McGill University, said the issue is not so much the load shift on the Earth's crust, but rather the increased fluid pressure in the fault that lubricates the rock, allowing the plate to slide.
"All earthquakes, except those produced by volcanic activity, are essentially the unsticking of faults," he said. In other words, if you pump fluid into a fault, it can reduce the friction and allow the rock to slide.
Could the stress transfers and the added melt from glaciers inject more fluid into the rocks, creating earthquakes?
He added that the decompression from melting glaciers could cause an increase in volcanic activity by releasing the liquid rock and its explosive potential.
At the same time, the number and severity of earthquakes appear to have increased over the last 30 years in tandem with accelerating glacial melt.
Some experts claim that jump can be explained by the increased number of seismograph stations -more than 8,000 now, up from 350 in 1931 -allowing scientists to pinpoint earthquakes that would otherwise have been missed.
Scientists have been tracking these powerful quakes for well over a century and it's unlikely that they have missed any during at least the last 60 years.
The U.S. Geological Survey says there were 1,085 major earthquakes in the 1980s. This increased in the 1990s by about 50 per cent to 1,492 and to 1,611 from 2000 to 2009. Last year, and up to and including the Japanese quake, there were 247 major earthquakes.
There has been also a noticeable increase in the sort of extreme quakes that hit Japan. In the 1980s, there were four mega-quakes, six in the 1990s and 13 in the last decade. So far this decade there have been two. This increase, however, could be temporary.
Hynes said there is some evidence that one earthquake can snowball into another until the Earth's crust has adjusted to the new pressure transfers.
Just consider this however - how can the number of earthquakes matter when the energy is logarithmic?
A 6 is 63 Terajoules, a 7 is 1995 Terajoules. How does it make sense to count them as numbers?
...I am grateful for your patience, and yes, I am learning from you and appreciate your 'mentorship.' But I would learn more, faster if you would quit assuming I have an agenda that you need to counter
if you would stop dealing with me like some subject-to-panic blonde-bimbo. I'll be happy to send you a check for said services once we get on track here
Does a single release of energy relieve stress on the entire system
...Your main assumption seems to be that one single release of energy relieves stress on the entire system
Your second assumption is based on the notion that there are and always will be only 7 primary tectonic plates, the secondary and tertiary plates are relatively unimportant, and no major rifts, fissures or other separations will occur to alter the current 'static' situation - I wonder if that's true.
This started out with the notion that strong earthquakes are increasing, I say they are not and have provided what I believe to be reasonable evidence to suggest that my suppositions are valid.
Part of that analysis involves the suggestion that stress and the relief of stress are best thought of in terms of energy especially since the build up is so calculated I understand. Indeed from the movements measured by GPS it should be possible to calculate the potential stress on a system, but to then say we had 10 earthquakes so that relieved it is patently wrong.
This is why I am saying you cannot 'count' earthquakes. I have made no mention of plates or of a single release doing the trick, just that one bigger quake may relieve more stress than a number of slightly smaller ones in magnitude. ...a multitude of small quakes do nothing much to release the stress on a fault.
sorry that you chose yet again to avoid the issues.
shows clearly that strong quakes have indeed increased over the past 30 years, as stated in the OP source article
Selected earthquakes of general historic interest.
As I stated VERY clearly, I'm asking whether or not a quake in part of the system CREATES stress in other parts of the system. YOU are the one focused on the (prehaps mistaken) idea that a quake relieves stress to benefit the whole system.
Nothing to do with what I said. My sources refer to quakes mag +6, and the question is whether or not quakes create stress elsewhere, and trigger a cascade.
I want to look at a complex system - you focus on single faults and presume that all quakes "release stress" to benefit a given fault and the whole system.
*1960 Selected Quakes*
1960 05 22 - Chile - M 9.5
1960 05 21 - Arauco Peninsula, Chile - M 7.9
1960 01 13 - Arequipa, Peru - M 7.5
*2004 Selected Quakes*
1. 2004 12 26 - Sumatra-Andaman Islands - M 9.1
2. 2004 12 23 - North of Macquarie Island - M 8.1
3. 2004 11 11 - Kepulauan Alor, Indonesia - M 7.5
4. 2004 09 05 - Near the South Coast of Honshu, Japan - M 7.4
5. 2004 02 07 - Irian Jaya, Indonesia - M 7.3
6. 2004 07 25 - Southern Sumatra, Indonesia - M 7.3
7. 2004 11 15 - Near the West Coast of Colombia - M 7.2
8. 2004 09 05 - Near the South Coast of Western Honshu, Japan - M 7.2
9. 2004 11 26 - Papua, Indonesia - M 7.1
10. 2004 11 22 - Off West Coast of South Island, N.Z. - M 7.1
11. 2004 02 05 - Irian Jaya, Indonesia - M 7.0
12. 2004 11 28 - Hokkaido, Japan Region - M 7.0
13. 2004 10 09 - Near the Coast of Nicaragua - M 7.0
14. 2004 11 09 - Solomon Islands - M 6.9
15. 2004 06 10 - Kamchatka Peninsula, Russia - M 6.9
16. 2004 12 14 - Cayman Islands Region - M 6.8
17. 2004 12 06 - Hokkaido, Japan Region - M 6.8
18. 2004 10 08 - Solomon Islands - M 6.8
19. 2004 06 28 - Southeastern Alaska - M 6.8
20. 2004 11 11 - Solomon Islands - M 6.7
21. 2004 11 02 - Vancouver Island, Canada Region - M 6.7
22. 2004 10 15 - Taiwan region - M 6.7
23. 2004 01 28 - Seram, Indonesia - M 6.7
24. 2004 10 08 - Mindoro, Philippines - M 6.5
25. 2004 05 29 - Off the East Coast of Honshu, Japan - M 6.5
*2009 Selected Quakes*
1. 2009 09 29 - Samoa Islands region - M 8.1
2. 2009 03 19 - Tonga region - M 7.6
3. 2009 09 30 - Southern Sumatra, Indonesia - M 7.5
4. 2009 08 10 - Andaman Islands, India region - M 7.5
5. 2009 10 07 - Vanuatu - M 7.4
6. 2009 01 15 - East of the Kuril Islands - M 7.4
7. 2009 01 03 - Near the North Coast of Papua, Indonesia - M 7.4
8. 2009 11 09 - Fiji - M 7.3
9. 2009 05 28 - Offshore Honduras - M 7.3
10. 2009 02 11 - Kepulauan Talaud, Indonesia - M 7.2
11. 2009 08 09 - Near the South Coast of Honshu, Japan - M 7.1
12. 2009 09 02 - Java, Indonesia - M 7.0
13. 2009 02 18 - Kermadec Islands region - M 7.0
14. 2009 10 24 - Banda Sea - M 6.9
15. 2009 08 28 - Banda Sea - M 6.9
16. 2009 08 03 - Gulf of California - M 6.9
17. 2009 04 07 - Kuril Islands - M 6.9
18. 2009 11 24 - Tonga - M 6.8
19. 2009 10 30 - Ryukyu Islands, Japan - M 6.8
20. 2009 10 08 - Vanuatu - M 6.8
21. 2009 10 07 - Celebes Sea - M 6.8
22. 2009 08 17 - Southwestern Ryukyu Islands, Japan - M 6.7
23. 2009 08 16 - Kepulauan Mentawai region, Indonesia - M 6.7
24. 2009 06 23 - New Ireland region, Papua New Guinea - M 6.7
25. 2009 04 16 - South Sandwich Islands region - M 6.7
26. 2009 01 15 - Southeast of the Loyalty Islands - M 6.7
27. 2009 11 17 - Queen Charlotte Islands region - M 6.6
28. 2009 11 08 - Sumbawa region, Indonesia - M 6.6
29. 2009 10 08 - Santa Cruz Islands - M 6.6
30. 2009 10 04 - Moro Gulf, Mindanao, Philippines - M 6.6
31. 2009 10 01 - Southern Sumatra, Indonesia - M 6.6
32. 2009 08 30 - Samoa Islands region - M 6.6
33. 2009 08 12 - Izu Islands, Japan region - M 6.6
34. 2009 08 10 - Santa Cruz Islands - M 6.6
35. 2009 04 18 - Kuril Islands - M 6.6
36. 2009 01 19 - Southeast of the Loyalty Islands - M 6.6
37. 2009 11 13 - Offshore Tarapaca, Chile - M 6.5
38. 2009 05 16 - Kermadec Islands region - M 6.5
1. I have stated repeatedly that I'm only looking at 6.0+M or 6.5+M quakes - so your continued insistence that lists include smaller quakes is not on point.
2. The 30-year increase of larger quakes in Japan flagged in the OP source article can be seen as predicting the March 11, 2011 Japan quake - and as bringing into question your basic assumption that quakes "relieve stress." …Looks like they create stress. NOTE: Even though you have not made the explicit statement, everything you say is based on that premise - else why keep saying really big quakes release more energy and thus, relieve more stress?
3. I've been trying to verify your data - can't do it without your info. Won't presume to check your calculations, but a list of the quakes you included with their magnitude and related "energy released" numbers would be good. Ie., what data did you base your graphs on?
In addition, the page verifies the data presented in the OP source article: quakes mag 6.0+ were in the single digits through the 60's - jumped - double digits by the 2000's; 35 in 2008, 52 in 2009, etc.
4. The USGS: Historic World Earthquakes Mag. 6.0 and Greater page lists quakes 6.0+M - copied the 6.5+M quakes here for 2004 and 2009 - as you say, the quakes are "selected" but the page DOES show a significant increase overall in 6.5M quakes from the 60's through to the present.
Lets say a 7.0 quake at 10km and a 7.0 at 100km would give the same energy, but if your computer(mesure equipement) is located on the earth surface, the one at 10km would give a much higher result?
i imagine they dont have sensors planted at depths of 100km, or maybe they have?
So many of the early data we can assume its not quite comparable with the recent ones?
…they have probably made exactly the same mistake as you, …please tell me how your source is in any way credible…
FROM THE CENTENNIAL CATALOG, ANSS AND USGS
Year, energy, NUMBER, energy per quake.
Originally posted by soficrow
reply to post by PuterMan
My source is USGS - I provided the link but here it is again: USGS: Historic World Earthquakes Mag. 6.0 and Greater.
As I posted earlier:
…the amount of energy involved is important. My questions are: How exactly is it important? Does the energy-release factor override (all) other factors? Does a single release of energy relieve stress on the entire system, thus maintaining geophysical homeostasis, or might it trigger a cascade that upsets the current equilibrium?
Your response: "… you cannot 'count' earthquakes. …one bigger quake may relieve more stress than a number of slightly smaller ones in magnitude."
I said: "the question is whether or not quakes create stress elsewhere, and trigger a cascade.
…(but) - you …presume that all quakes "release stress" to benefit a given fault and the whole system."
Your response: "I have made no such statement." Then you say, contemptuously, "…quakes relieve stress. …Just what exactly do you think a fault rupture is?"
You ARE saying that quakes relieve stress,
which implies that the release serves to maintain geophysical homeostasis,
which I question. But when I try to paraphrase and clarify, you say I'm putting words in your mouth.
I requested your data and links, wanting to review the energy-release of 6.5+M quakes - you provided conclusions that cannot be verified, without links, but which supposedly include all quakes 1.5+M.
FROM THE CENTENNIAL CATALOG, ANSS AND USGS
Year, energy, NUMBER, energy per quake.
Since you have been pressing me this is a quick version based on the USGS Centennial Catalogue for dates between 1960 and 2001, on ANSS data from 2002 to 2008 inclusive and on data I have collected from USGS 7 day listings for 2009 and 2010.
I say a quick version because I have not checked all the latest 7 day versions against the ANSS catalogue however the difference will be very minor and if anything would probably very slightly lower the figures for 2009 and 2010.
These are only for Magnitude 6.5+ as data before 1964 for lower magnitude quakes is not in the Centennial.
…I know I'm not stupid, so I can only conclude you're trying to do a BSBB number on me.
You can fool some of the people all of the time, and all of the people some of the time, but you can't fool all of the people all of the time.
- Abe Lincoln
Originally posted by Aromaz
So the correct statement is: The number of earthquakes does not matter; the energy value does.