Has there been an increase in earthquake activity?
Cross posted from my personal blog: Has there really been more earthquakes than average?
Damage in Santiago, Chile. Photo by Reuters/Marco Fredes
After the massive earthquake this past weekend in Chile, MSNBC published a sensationalistic piece entitled, “Is nature out of control?” The Wall Street Journal asked if three massive earthquakes around the world in two months are related and a cause for alarm. The mainstream media, always searching for sensationalistic or fear mongering news, has latched onto the question; are we seeing more earthquakes than normal?
Well, not really. Let’s take a look at how many earthquakes occur each year on average. The USGS has a fascinating page of earthquake facts and statistics, with the following table:
| Magnitude | Average Annually |
|---|---|
| 8 and higher | 1 ¹ |
| 7 – 7.9 | 17 ² |
| 6 – 6.9 | 134 ² |
| 5 – 5.9 | 1319 ² |
| 4 – 4.9 | 13,000 (estimated) |
| 3 – 3.9 | 130,000 (estimated) |
| 2 – 2.9 | 1,300,000 (estimated) |
¹ Based on observations since 1900.
² Based on observations since 1990.
Let’s take earthquakes based in the M6.0 – M6.9 range. Why am I picking earthquakes in the magnitude 6 range? It’s arbitrary. You can repeat this process for earthquakes of any range. Based on data recorded since 1990, we’d expect to see an earthquake within this magnitude range occur every 2.7 days or so.
So here we are, on March 1st, 2010, the 60th day of the year. How many earthquakes in the M6.0 – M6.9 range have we had this year? According to this handy search tool from the USGS, there have been 25 earthquakes of M6.0 – M6.9 in 2010.
PDE-Q 2010 01 02 084532.05 12.42 141.96 2 6.1
PDE-Q 2010 01 03 214805.32 -8.74 157.48 26 6.6
PDE-Q 2010 01 05 045538.91 -58.17 -14.70 10 6.8
PDE-Q 2010 01 05 121532.21 -9.02 157.55 15 6.8
PDE-Q 2010 01 05 131142.82 -9.05 157.89 35 6.0
PDE-Q 2010 01 09 055130.47 -9.13 157.63 12 6.2
PDE-Q 2010 01 10 002739.32 40.65 -124.69 29 6.5
PDE-Q 2010 01 12 220041.49 18.39 -72.78 10 6.0
PDE-Q 2010 01 17 120001.08 -57.66 -65.88 5 6.3
PDE-Q 2010 02 01 222816.92 -6.11 154.46 32 6.2
PDE-Q 2010 02 05 065905.64 -47.90 99.66 1 6.2
PDE-Q 2010 02 06 044458.40 46.84 152.73 30 6.0
PDE-Q 2010 02 07 061000.24 23.48 123.64 21 6.3
PDE-Q 2010 02 09 010344.44 -15.05 -173.49 10 6.0
PDE-Q 2010 02 13 023428.69 -21.89 -174.77 11 6.1
PDE-Q 2010 02 15 215148.56 -7.19 128.78 130 6.2
PDE-Q 2010 02 18 011319.93 42.61 130.70 580 6.9
PDE-Q 2010 02 22 070054.60 -23.72 -175.98 35 6.0
PDE-Q 2010 02 27 065234.57 -34.80 -72.65 35 6.2
PDE-Q 2010 02 27 071228.81 -33.83 -71.91 35 6.0
PDE-Q 2010 02 27 073718.52 -36.84 -72.54 35 6.0
PDE-Q 2010 02 27 080123.93 -37.71 -75.21 37 6.9
PDE-Q 2010 02 27 082529.61 -34.76 -72.37 35 6.1
PDE-Q 2010 02 27 154541.09 -24.59 -65.43 38 6.3
PDE-Q 2010 02 27 190008.01 -33.42 -71.91 34 6.3
That works out to roughly one earthquake in the magnitude 6.0 range every 2.4 days. That doesn’t seem unreasonable, but we should do some further work to put it in context. We can plot up the number of earthquakes per year and come up with a standard deviation, assuming a normal distribution of earthquakes in any given magnitude range.
2010 25 2.4
2009 142 2.57
2008 168 2.18
2007 178 2.05
2006 142 2.57
2005 140 2.61
2004 141 2.60
2003 140 2.61
2002 127 2.9
2001 121 3.02
2000 146 2.51
1999 116 3.15
1998 109 3.35
1997 120 3.04
1996 149 2.46
1995 183 1.99
1994 146 2.5
1993 137 2.66
1992 166 2.20
1991 108 3.38
1990 109 3.35
Total results: 21
Mean (average): 2.67143
Standard deviation: 0.41732
So, the number of magnitude 6 earthquakes that we’ve had in 2010 falls within one standard deviation of the mean. If we were to plot up a graph, it’d look like this. The error bars represent one standard deviation.
Awesome! Well, what about those ranges of values that fall outside of one standard deviation from the mean? For those that don’t understand how statistics works, check out the following bell curve from Wikipedia.
This shows roughly the percentage of values that you’d expect to fall within a specific standard deviation away from the mean value.
Dark blue is less than one standard deviation from the mean. For the normal distribution, this accounts for about 68% of the set (dark blue), while two standard deviations from the mean (medium and dark blue) account for about 95%, and three standard deviations (light, medium, and dark blue) account for about 99.7%.
So, if we modify our graph to show an error bar of 2 standard deviations, you’ll notice that every result since 1990 fits inside this model! Simply put, there is absolutely nothing strange happening.
In fact, thanks to this normal curve you can basically predict, with a 99.7% chance of success, that an earthquake of equal / greater than M6.0 will occur somewhere around the world within the next 3.5 days.
Alright, so what’s with all the coverage on earthquakes? It sure seems like a lot is happening, right? We can attribute this to observer bias. The massive devastation in Haiti warranted a large amount of news coverage. Because this is so fresh in everyone’s mind, people are more likely to notice any news or information related to earthquakes.
It’s the same principle that happens whenever you acquire some new toy, gadget, or piece of clothing. Suddenly, you notice that particular item around all the time. It’s like everyone has it.
So, bottom line, the Earth isn’t becoming more active, more dangerous, or even “out of control.” Despite the fear mongering and what esteemed mainstream media networks would have you believe, the simple reality is that the numbers prove things are happening at an expected rate. Keep that in mind the next time a large earthquake happens and everyone is wondering why the Earth seems so active!
Similar Posts on Geology News:
- Earthquake Fatalities High in 2008
- M7.8 Earthquake in Central China
- New Forecast for California Earthquakes
- Earthquakes in the Midwest
- No Warning for 2004 Parkfield Quake
Awesome analysis!! Thank you for straightening this out.
Earthquakes are part of the earths natural activity. Most earth quakes are not even noticed. But the real question has not been answerd. Is there an incease on earthquake devestation and fatalaties comapared to the past? I would like to see a bell curve or bar graph on that question based on number of people killed becasue of earthquakes. Will the graph disprove the signs of the times.
Of course there are more people affected by earthquakes, even if earthquake activity was the same – there are just more people!
It seems to me that the media is just sensationalizing the earthquakes more these days thanks to the pictures and information they can receive from people in the areas that these are happening. There hasn’t been more earthquakes, just more news coverage of the earthquakes.
i dont believe this their has been almost a big earthquake every day for two weeks now so get your facts strait
The numbers are straight from the USGS. If you’d like to run them yourself, be my guest!
Anyway, not sure I’d trust statistical analysis from someone who doesn’t understand proper grammar.
For curiosity’s sake, I ran the numbers again.
Today is March 12th, the 71st day of the year.
According to the USGS, there have no been 41 M6.0 – M6.9 earthquakes so far in 2010 (Whoa! One would assume that a lot of those are aftershocks from the great Chilean earthquake).
That means we’ve had an earthquake in the M6 range every 1.73 days. Alright, that number is getting down there. Is it a cause for alarm?
No. Why?
The standard deviation is 0.417 days with a mean of 2.671 days between earthquakes of this size (if you’re curious how I got those numbers, reread the article). Since we can expect to find 99.7% of all results within 3 standard deviations of the mean, let’s figure that out. 0.417 x 3 days = +\- 1.251 days.
2.671 days – 1.251 days = 1.42 days.
If you start seeing a M6 earthquake more than every 1.42 days, then come talk to me.
There’s nothing to worry about.
“Cross posted from my personal blog: Has there really been more earthquakes than average?”
I believe the word you were searching for was “have” ie: ‘Have there been more earthquakes in the past year versus the average number of earthquakes we have had in previous years?’ (all of this being past-tense).
“Anyway, not sure I’d trust statistical analysis from someone who doesn’t understand proper grammar.”
Well maybe if you knew how to spell people would get their facts STRAIGHT! you obviously need to go back to 1st grade if you don’t know how to spell straight…
i will run them myself because clearly you only accounting for only 6.0-7.0 earthquakes if you are going to do research on only a quarter of the quakes you wont get all the info you need you need to start at 6.0 and go all the way up to the highest magnitude and compare that to the other years because you are only showing a little bit of info!!!!!!
Hah, okay Austin.
Here’s the break down for other magnitudes in 2010. If you want to search yourself, you can use this tool:
http://earthquake.usgs.gov/earthquakes/eqarchives/epic/epic_global.php
2010 earthquakes:
M7.0 – M7.9: 3 earthquakes so far in 2010 (yearly average: 17)
M8.0 – M8.9: 1 earthquake so far in 2010 (yearly average: ~1)
If you want to account for M7 earthquakes:
365 days / 17 eq’s per year = 21.47 days per EQ.
2010: 71 days / 3 eq’s in 2010 = 23.67 days per EQ.
Magnitude 8 earthquakes? Average is about 1 a year. We had one.
What if we have another 8.0 earthquake? That would be TWO TIMES the 100-year average! Joe Biden might call it a BFD.
aww who cares this austin kid doesnt know how to spell STRAIGHT so if he doesnt know how to spell straight then he obviously doesnt know how to work with averaging numbers. i say he needs to go back to 1st grade. you are obviously smarter than him. :) haha lol
On the first chart above, where there are the headings: “Magnitude” and “Average Annually” there is the following notation: 2 Based on observations since 1990. I have to wonder, why only use the data collected since 1990? The USGS website also has data from 1980 to 1989 for earthquakes ranging in magnitude from 6.0 to 9.9. Why not use that data too? In fact, the more years of data we can use to establish our baseline, the more reliable our numbers would be.
Using data from the USGS website, I took a couple of minutes to graph earthquakes in the 6.0 to 9.9 range for the following decades: 1980 – 1989, 1990-1999, 2000 – 2009. Just a glance at the graph I came up with shows that there were less earthquakes in the 1980′s than in the following decades. For example, during the 1980′s the year with the most earthquakes (1983) still had LESS earthquakes than any year from 2000 through 2009.
If you want to make your own graph and see for yourself – the data is fairly easy to find on the USGS website.
Thanks for this! :)
“2010 March 8 astanix
It seems to me that the media is just sensationalizing the earthquakes more these days thanks to the pictures and information they can receive from people in the areas that these are happening. There hasn’t been more earthquakes, just more news coverage of the earthquakes.’
There have been 245 earthquakes in Alaska in the last 7 days. These quakes have gone UNREPORTED by the media. I’d call 245 quakes in one state in 7 days pretty damn sensational if you ask me.
Dave,
Very cool research that you have done here! I would love to see this type of research presented for earthquakes of a magnitude of 7 or higher, since those are the ones considered major earthquakes and the ones we have been seeing covered more in the news lately.
According to this website: http://www.geo.mtu.edu/UPSeis/magnitude.html, we only get a magnitude 8 earthquake or higher every 5-10 years, not every year. However, the following website shows a much higher average than that, especially in the last 10 years: http://earthquake.usgs.gov/earthquakes/eqarchives/year/mag8/magnitude8_1900_date.php
earthquakes are going to continue to get worst and all this is suppost to happen because jeuse christ say in mattew chapter 24 verse 7 . (for nation will rise agianst nation and kindom agaist kingdom , and there will be food shortages and earthquakes in one place after another. ALL THESE THINGS ARE THE BEGINNING OF PANGS OF DITRESS! )now dont we see all this now this is just the beging of the end of this system of things
Maybe it’s the first time you have noticed these things, but for Christ’s sake man, there have been wars, food shortages, and earthquakes since thousands of years before Jesus. I suppose this world has been ending since its beginning, hallelujah!
Dave,
I’m thinking it would be a useful public service to run the numbers again now that we’ve had Mexico and Sumatra pop off within 2 days of each other… doubtless their proximity of timing is going to have people asking these same questions again. I’d love to have an up-to-date analysis to point to…
Pretty please?
Thanks,
C
I find this study interesting – but I noticed on the USGS info, 2009 was a pretty stiff spike – not like 1900′s though. Since we’ve had the 1 big one early on this year, it seems perhaps we’re in for another action-packed 2010 – we’ll see. But if so, that would be a change – most of the spikes are single-year events. If we start to have spikes of more than one year in length, there could be something happening… I would be interested though in a more thorough comparison between this data, and other geologic activity such as volcanoes, rockslides, oceanic tides/temps, to see if there is some correlation in a frequency change. Things like Yellowstone becoming more active, or other changes might point to the beginnings of a steady increase in some activity.
Consequently, we do get more information from world news because of the increase in communication, which might also be contributing, but it’s certainly something to be aware of.
Dave, there have been at least two more 7-8 mag. earthquakes since your research. Fortunately, even if that deviates from the mean, we still have the rest of the year! Nice work on the data. I feel better now knowing that there’s nothing unusual going on.
Ran it for 8.0-8.9 quakes from 1973 to 1999 it reported 15 quakes in this magnitude. Then from 2000 – 2010 it reported 13, thow its data is old I would say it was closer to 14 or 15. So what in 26 years there was 15 quaks, and in only 9 years, there have been almost as many. But ofcourse I must be an idiot because earthquake activity has not gone up at all.. yea right.
Hey, thanks for posting this. I had to forward the USGS info to my inlaws who are Southern Baptist evangelicals convinced that the end of the world is fast approaching because of the past three earthquakes. You know, “signs” of the apocalypse? Sigh…no, they aren’t educated; and yes, they homeschool their children.
Whether you believe in the apocalypse or not, you’re Sinicism towards people that do is sad. Are you one of those “smart” people that bought into the man caused global warming con? It is just a matter of fact that things are getting worse in many areas including natural disasters. Look at the most powerful country in the world now bowing to the Chinese with its hand out begging for more money… Very sad but true. You don’t have to believe, but it won’t change the facts. And by the way, ARE THESE HOME SCHOOLED PEOPLE DUMB ALSO; Frank Vandiver (President – Texas A&M), Fred Terman (President – Stanford), William Samuel Johnson (President Columbia), John Witherspoon (President of Princeton), Stonewall Jackson, Robert E. Lee, Douglas MacArthur, George Patton, Alexander Graham Bell, Thomas Edison, Cyrus McCormick, Orville Wright & Wilbur Wright, George Washington, Thomas Jefferson, John Quincy Adams, James Madison, William Henry Harrison, John Tyler, Abraham Lincoln, Theodore Roosevelt, Woodrow Wilson, Franklin Delanor Roosevelt, and many, many more. Go to http://www.home4schoolgear.com/famoushomeschooler.html.
Intelligence is listening to the right source of information past and future then one must decide for ones self if life is temporary or everlasting…
Thanks for the analysis. That was a very professional way of presenting it.
I think the proper question is this:
Are major earthquakes striking major metropolitan areas more often than years past?
Interesting article in the LATimes. EQ activity on a global basis may be “average” but on a regional basis it appears to not be “average”.
http://latimesblogs.latimes.com/lanow/2010/04/california-sees-increase-in-earthquake-sesimologists-fight-twitter-rumors.html
Hi! very interesting article, specially because you took data and converted it into information, and yes, the statical work is really good, but also as much people comment here, probably, and I say probably because I dont have the right data, there have been earthquakes with more impact, just happened again in China, so in this year, we have had three (Haiti, Chile, China) with a lot of dead people (sadly) and high economical cost (buildings, roads, houses), so I dont remember last year three earthquakes like that… :( and there’s still a lot of 2010 to go, I think this analisys would be better at the end of the year. Good day.
Thanks for doing the work. I’ve been following this activity lately and it was starting to worry me. I’m glad to hear it’s within the normal range.
We had one last month in Chicago which never happens and that got me paying attention. If it starts to rain frogs, I’ll get back to you.
That’s great that you have a handle on the numbers and everything. Unfortunately numbers are merely symbols and are virtually meaningless without context. In this case, your context is yearly earthquake averages.
Since it is early in the year, you should divide the averages of the previous years for the correct proportion. Do earthquakes normally average something like one over 6.0 every week? I don’t think so…
Here’s what I do know, I don’t remember reading about a new earthquake and/or volcano every week last year. As I visited the Science (including Geology) offices at USI and carefully read the huge poster about the New Madrid Fault, everybody seemed extremely nervous. I mean, why are they so uptight? It’s just freaking Geology, I was waiting to talk to a professor, reading posters and looking at fossils RED ALERT!! Lol. In addition, it is my understanding that mountaintop and glacial ice has been melting, and mountains (which are connected to tectonic plates) have been moving at accelerated rates due to the weight loss.
Don’t bury your head in the sand friend. Denial is not part of the scientific process. And don’t over-specialize on me and act like it’s not your job to advise people to know where their gas shutoff valves are and to have some distilled water on hand. It’s just common sense (not just for commoners).
*7.0 every week…
What’s up, I hit this site alot since it is one of the top results on Google right now. I ran a few numbers myself, and came up with some conclusions that further knowledge of statistical analysis may inform:
(every 365 days) 8+ 1/y
(every 021 days) 7 – 7.9 17/y
(every 2.7 days) 6 – 6.9 134/y
(every 396 mins) 5 – 5.9 1319/y
(every 40 mins) 4 – 4.9 13,000/y
(every 04 mins) 3 – 3.9 130,000/y
(every 24 secs) 2 – 2.9 1,300,000/y
Just using the calculator to help me understand this was pretty relaxing. Still, I think these averages aren’t helping my understanding very much. I mean, measuring things like this by the year is a really awkward yardstick. Predicting an earthquake or understanding transtectonic inertial communication with today’s technology seems analogous to picking a GPS point from cellular triangulation data. It really does seem to me that recent geological activities have had more global correlation lately. These are the kinds of patterns that this class of statistical analysis is apparently not able to illuminate further. Not only do we need to see different arbitrary classes of magnitude compared by yearly average, but we also need to see how often earthquakes happen and look at clusters of events and rate those events by probable correlation.
How long does it take for a volcano’s force to transfer to the leading edges of its home plate? How would a volcano in the middle of a plate be affect tectonic inertia compared to a volcano on a fault?
Do continential plates kiss with English? How far does a plate have to move before the contact materials reach their structural failure limits? How does lateral motion affect the abraison differently from vertical motion? How would melting ice modify the vector dynamics through the geological interfaces? …
Thank you for that I’ve been hearing to much hype about earthquakes and the end of the world lately. Everyone is talking about this polar shift like in the resent movie 2012, can you shine any light on the possibility of something like this happening.
About those suspicious ranges….
We love science, this is what it is all about. Lets get to the facts. I think these apparently comforting numbers are of little value without being refined a bit. And trust me I want them to be comforting! But that’s the trouble with bias isn’t it? It cuts both ways.
Unfortunately, this article covers only the last 20 years. See? 1990-2020. What are the numbers on earthquakes since we have been recording? The article points out that we have been keeping records much longer. A century in fact.
Better detection makes a difference only for small quakes. Naturally there are more observers (more people on the planet to get shaken up and bother to take note) with better tools, so we see more.
So narrow the numbers to places that have had continual habitation. Then make sue they and lie along active fault lines. The numbers should tell the story over the century.
Bad method you cry? Maybe. Then why not try adjusting for the increase in numbers of people and the increase in number and sensitivity of seismographs. Is that so hard? Those are precisely known quantities.
Since large earthquakes are the ones that we notice, lets look at numbers for quakes 6.0 and above for the last hundred years. What’s the story?
Excuse me..if maths is not an opinion.. there HAS been a definitive increase in earthquakes, which you can see by analysing the very data of USGS, the same data they use to tell us everything is fine:
last updated 27 February 2010
Source: – http://www.johnstonsarchive.net/other/quake1.html
(all data from USGS)
World Earthquakes, 1970-2010
year number of earthquakes in magnitude range estimated deaths
8.0 to 9.9 7.0 to 7.9 6.0 to 6.9 5.0 to 5.9 5.0 to 9.9
1970 0 20 110 1,195 1,325 68,202
1971 1 19 112 1,331 1,463 1,279
1972 0 15 110 1,316 1,441 11,179
1973 0 13 95 1,331 1,439 659
1974 0 14 99 1,312 1,425 5,440
1975 1 14 107 1,447 1,569 12,372
1976 2 15 114 1,649 1,780 697,309
1977 2 11 89 1,686 1,788 2,849
1978 0 16 93 1,526 1,635 15,192
1979 0 13 100 1,366 1,479 1,475
1980 1 13 105 1,299 1,418 8,620
1981 0 13 90 1,168 1,271 5,223
1982 0 10 85 1,425 1,520 3,328
1983 0 14 126 1,673 1,813 2,372
1984 0 8 91 1,579 1,678 174
1985 1 13 110 1,674 1,798 9,846
1986 1 5 89 1,665 1,760 1,068
1987 0 11 112 1,437 1,560 1,080
1988 0 8 93 1,485 1,586 26,552
1989 1 6 79 1,444 1,530 617
1990 0 18 109 1,617 1,744 52,056
1991 0 16 96 1,457 1,569 3,210
1992 0 13 166 1,498 1,677 3,920
1993 0 12 137 1,426 1,575 10,096
1994 2 11 146 1,542 1,701 1,634
1995 2 18 183 1,318 1,521 7,980
1996 1 14 149 1,222 1,386 589
1997 0 16 120 1,113 1,249 3,069
1998 1 11 117 979 1,108 9,430
1999 0 18 116 1,104 1,238 22,662
2000 1 14 146 1,344 1,505 231
2001 1 15 121 1,224 1,361 21,357
2002 0 13 127 1,201 1,341 1,685
2003 1 14 140 1,203 1,358 33,819
2004 2 14 141 1,515 1,672 228,802
2005 1 10 140 1,693 1,844 82,364
2006 2 9 142 1,712 1,865 6,605
2007 4 14 178 2,074 2,270 712
2008 0 12 168 1,768 1,948 88,011
2009 1 16 142 1,700 1,859 1,787
2010 1 2 18 258 279 230,000
EARTHQUAKES MAGNITUDE from 6.0 to 6.9
SINCE 1970 TO 1991 (included) : 2.214 = YEARLY AVERAGE for 21 years: 105
SINCE 1992 TO 2009 (included) : 2.579 = YEARLY AVERAGE for 18 years: 143
AVERAGE INCREASE OF 37% IN 18 YEARS
EARTHQUAKES MAGNITUDE from 7.0 to 7.9
SINCE 1970 TO 1991 (included) : 285 = YEARLY AVERAGE for 21 years: 13,5
SINCE 1992 TO 2009 (included) : 260 = YEARLY AVERAGE for 18 years: 14,4
AVERAGE INCREASE OF 7% IN 18 YEARS
EARTHQUAKES MAGNITUDE from 8.0 to 9.9
SINCE 1970 TO 1991 (included) : 10 = YEARLY AVERAGE for 21 years:: 0,47
SINCE 1992 TO 2009 (included) : 20 = YEARLY AVERAGE for 18 years: 1,11
AVERAGE INCREASE OF 140% IN 18 YEARS
AND I am not considering data prior to 1970…
Emanuela, Italy