Are Earthquakes on the rise?

Question

This came across my social media feed:

USGS Earthquakes since 1973

U.S. Geological Earthquakes Survey
1973 - 4,539 Earthquakes
1974 — 4,528 Earthquakes
2000 — 19,131 Earthquakes
2010 — 23,040 Earthquakes
2011 — 22,392 Earthquakes
2013 — 89,622 Earthquakes
2014 — 118,404 Earthquakes
2015 — Over 36,000 Earthquakes...

One pastor gave this some context:

Earthquakes on the rise, USGS stats confirm. Jesus predicted 2000 yrs ago, "And GREAT EARTHquakes shall be in divers places, and famines, and pestilences; and FEARFUL sights and great signs shall there be from HEAVEN." (Luke 21:11) Christians, signs BELOW being fulfilled...now watch for signs from ABOVE!

The data seems to be a little selective, and I assume earthquake detection instruments have increased in both number and sensitivity since 1973.

Are earthquakes numbers increasing significantly and consistently since 1973?

Note that there is no such thing as the "US Geological Earthquakes Survey". — David Richerby, May 15 '15 at 09:02
@sweeneyro, it should probably be read with an implicit "so far" for 2015 (it's not over yet, remember). If this was published in March, it surely would support the "is on the rise" statement. — Zano, May 15 '15 at 14:50
Assuming the 36k stat was found _today_, and earthquakes are evenly spaced throughout the year (I don't think this is the case, but for simplicity), that comes out to an expected 98060 earthquakes in 2015. If 36k was the number as of Apr 22, then the expected number would be 118378, almost the same as 2014 — Izkata, May 15 '15 at 15:03
The quote from the pastor should be removed, as it doesn't add anything to this question. It could possibly be a separate question, such as "Is the increase of earthquakes a sign of the end times?" but I kind of doubt it would be on-topic here. — Reinstate Monica -- notmaynard, May 15 '15 at 15:24
@David, I'm not sure what you mean there is no such thing. There is the USGS and they would do earthquake surveys among other things. Taking the title from a chart and saying it doesn't exist is a silly proposition. I claim, there is no such organization as "Worldwide traffic fatalities"! — Octopus, May 15 '15 at 21:22
@Octopus Well, what does the heading mean? It can't mean the data came from an organization called the US Geological Earthquake Survey because there is no such organization. It can't mean that it's an earthquake survey by an organization called US Geological, because there is no such organization. It seems unlikely that it's a US survey of geological earthquakes, because earthquakes are geological by definition so that would be redundant. In contrast, "worldwide traffic fatalities" has an obvious meaning. — David Richerby, May 15 '15 at 21:42
did the definition of "earthquake" change maybe? I know that's a trick being employed by lawyers and environmentalists seeking to shut down gas and oil extraction here, calling every minor tremor that knocks over a flower pot "an earthquake" and demanding massive compensation. — jwenting, May 16 '15 at 09:59
There is no lower of limit for the magnitude of an earthquake, therefore, this question is not meaningful without stating the minimum moment magnitude where we start counting. — gerrit, May 19 '15 at 09:20

score 24 · Accepted Answer · answered May 15 '15 at 02:10

24

The title of this 2011 paper pretty much answers the question by itself: Global risk of big earthquakes has not recently increased.

(For the record: Peter M. Shearer and Philip B. Stark, doi: 10.1073/pnas.1118525109 PNAS January 17, 2012 vol. 109 no. 3 717-721)

They noted that there had been an increase in large earthquakes in 2004-2011, and some other apparent clustering, and looked back over the data since 1900 to see if there was sufficient statistical evidence to suggest that large earthquakes were occurring more frequently, or whether it could just be explained by chance.

Our conclusion that the global threat of large earthquakes has not recently increased is based both on the lack of statistical evidence that regionally declustered seismicity is temporally heterogeneous on a global scale and on the implausibility of physical mechanisms proposed to explain global clustering. [...] The recent elevated rate of large earthquakes has increased estimates of large earthquake danger: The empirical rate of such events is higher than before. However, there is no evidence that the rate of the underlying process has changed. In other words, there is no evidence that the risk has changed, but our estimates of the risk have changed.

While this focussed on large (Magnitude 7 and above) earthquakes, rather than all measured earthquakes, like the source infographic did, I think this is appropriate because (a) it lowers any effect caused by sampling error reduced as more numerous and more sensitive equipment is produced and (b) magnitude 1 and 2 tremors aren't what people are thinking when they hear the word 'earthquake'.

answered May 15 '15 at 02:10

Oddthinking

140,378
46
548
638

4

The OP is specifically asking about US earthquake stats, though. Those are increasing, simply due to heavy increases in Fracking and other mining practices. (I would make this an answer but I'm at work) – The Forest And The Trees May 15 '15 at 08:02
8

@TheForestAndTheTrees I don't think you can infer that the question is about the US. The source image refers to the "US Geological Earthquakes Survey" but there is no such thing. There is an organization called the US Geological Survey (USGS), who measure earthquakes worldwide. They presumably release data about the number of earthquakes in the US and also worldwide so it's not at all clear what the data in the source image refers to. – David Richerby May 15 '15 at 09:02
3

@TheForestAndTheTrees that's a bold claim and you should prove it. – edc65 May 15 '15 at 12:50
4

I'm sorry, but I have to agree that this is a poor response. There is a well-known increase in low magnitude earthquakes, likely due to fracking. For example, I'll cite the [USGS](http://earthquake.usgs.gov/research/induced/). I think that these are much more relevant to the question than large, magnitude 7+ earthquakes. After all, the original image was always talking about thousands of earthquakes per year, but there are only tens of mag 7+ earthquakes per year [source](http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php). – KAI May 15 '15 at 13:51
1

This answer might address what the pastor said though (since he qualifies it with "great" earthquakes). – KAI May 15 '15 at 13:52
Is the number of "large" earthquakes high enough to base ANY meaningful statistics on? – user5341 May 15 '15 at 14:20
1

@KAI - Your own links says "Hydraulic fracturing, commonly known as “fracking,” does not appear to be linked to the increased rate of magnitude 3 and larger earthquakes." – user5341 May 15 '15 at 14:23
@DVK Yes, I cleaned that up a tiny bit in the response that I just wrote. My understanding is that you have the fracking itself, then the people who do the fracking dispose of wastewater in injection wells (as the sources I linked say, and you can find many others). The belief is that the injection wells might actually cause the earthquakes, not the fracking itself. A distinction that often gets lost in the media, and I did not correctly make it either. – KAI May 15 '15 at 14:31
@DVK: I excerpted out a sentence that said "The estimated global rate of very large (M > 9) earthquakes is still very uncertain because only five such events have occurred since 1900.", but by the time you get to magnitude 7, there are around 5-10 per year. – Oddthinking May 15 '15 at 14:56
@KAI - "might" isn't "is" – user5341 May 15 '15 at 15:40
@Oddthinking There are roughly a hundred thousand earthquakes per year greater than magnitude 3 per the link I cited earlier. To used ~10 as a proxy to track the number of all of them is surely questionable. – KAI May 15 '15 at 16:06
4

@DVK I'm using "might" is the conservative way that scientists use it. In other words, in the sense that it takes a while for things to be settled. There are a number of studies which state that wastewater wells and earthquakes are linked. For example, [this one](http://www.sciencemag.org/content/345/6192/13.summary) from Science magazine. However, since this is an ongoing topic of research, I am willing to admit the possibility that the conclusions from such studies are incorrect, although I think it unlikely. – KAI May 15 '15 at 16:13
@KAI: It isn't a proxy to track all of them. It is an exact measure of the earthquakes large enough to be of concern to life and property. – Oddthinking May 15 '15 at 16:24
1

@Oddthinking I don't understand how an earthquake being large enough to be of concern to life and property is at all relevant to the question of "are earthquake numbers increasing significantly". If your answer isn't tracking all earthquakes in a meaningful way, I don't see how it is addressing the question as asked (although it may address the side issue of the quote by the pastor as stated above). – KAI May 15 '15 at 16:28
3

@KAI: Fair question. My argument is that when someone says on Facebook "Earthquakes are becoming more frequent", the mental model people have is of more devastating earthquakes, not more tremors only detectable on a seismograph. – Oddthinking May 15 '15 at 16:31
1

@Oddthinking Well, as somebody from the US, when I see something that says "earthquakes are on the rise", I immediately think of fracking since that is very controversial here and likely linked to smaller earthquakes (through wells). If you go to google you will see that this is not a personal idiosyncrasy - e.g. "increase in earthquakes" has roughly half the results be links to stuff on the link between fracking and earthquakes. So I think it is reasonable to be more literal about the question. – KAI May 15 '15 at 16:43
@Kai: Fair point. – Oddthinking May 15 '15 at 16:54
Re: the study provided; "The authors claim no conflict of interests." How do we see who sponsored/paid for this study? Aka, how do I prove no conflict of interest myself and not just take their word for it? – HC_ May 15 '15 at 21:05
1

@HC_: You can't prove that someone had no conflict of interest. You punish non-disclosure if they are found out to have one, but more importantly, you redo the data gathering and analysis, and reproduce the result, and you compare this result with similar studies. You avoid unsubstantiated as hominem attacks on authors who publish science that fails to meet an ideology. – Oddthinking May 16 '15 at 00:44
@Oddthinking thank you -- not sure I understand exactly. Is the source of funding for a study not required to be public information? That is mainly what I'm wondering. – HC_ May 18 '15 at 15:36

KAI · Answer 2 · 2015-05-15T18:07:25.603

I cannot confirm the numbers in the original image, although some of the recent numbers appear to be roughly consistent with USGS numbers.

However, the general point seems to be correct: the number of earthquakes has been increasing per year. But, the pastor is not correct: the number of "great" earthquakes is not increasing (see the response by Oddthinking). That is, the number of small earthquakes has been increasing by a large factor in some areas, almost certainly due to humans (wastewater injection wells from fracking, etc), while the number of large earthquakes has not.

For example, this USGS site shows that the rate of earthquakes from much of the US was roughly constant until the year 2000, but has been rapidly increasing since then.

enter image description here

This study from Oklahoma, a hotbed of fracking, concludes:

The seismicity rate in 2013 was 70 times greater than the background seismicity rate observed in Oklahoma prior to 2008. While unlikely, this rate could have been potentially explained by natural variations in earthquake rates from naturally occurring swarms. The seismicity rate is now about 600 times greater than the background seismicity rate, and is very unlikely the result of a natural process.

I'm not exactly clear on how these large, local increases in earthquakes would change the global number of earthquakes, but it should make the original claim plausible.

That graph is in very odd units. Why plot cumulative number of earthquakes rather than earthquakes/year? — reirab, May 15 '15 at 17:39
@reirab I would guess two reasons: To imply "we don't have data before this date" instead of "number of earthquakes were the same before this date" without having to state it, and so that the spike at the end is more pronounced than it would have been with earthquakes per year (like right around where 2013 would be, the rise drops off for a short period) — Izkata, May 15 '15 at 20:32

Are Earthquakes on the rise?

2 Answers2