Use these links to navigate through this site
Hi guys,
I'm a bit worried over the major earthquakes we've had this year. I went to USGS to check on statistics, and it seems that 2010 has had far more magnitude 7.0 - 7.9 earthquakes than is expected for any given year, and 2010 hasn't even ended yet. Is this a cause for concern?
http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php
Far more? There have only been 19. We had 18 three times in the 1990s. We had 20 in 1970, 19 in 1971. When you're talking about average norms, half of the values will always be above the average, and half below. There's nothing strange about 19.
Regarding earthquakes in general, you also have to realize that, over the last few decades, detection has reached an all-time high due to sensors gradually being place at more and more locations. Due to this progress, even our averages are probably on the low side and can be expected to increase over time. That doesn't mean we're having more quakes. It just means scientists are able to detect more.
Lastly, bear in mind that quakes are more likely to hit populated regions as populations increase, so you're more likely to hear about them.
Whan studying statistics such as this, what's important is not just the average result but also the scatter or spread of results. When the numbers involved are small (such as for earthquakes in the magnitude range 7.0 to 7.9) a relatively large scatter is not surprising.
Suppose you toss a coin 10 times. Will you get 5 heads and 5 tails? Quite probably you won't. You could well get 6,7 or even 8 heads. Now toss your coin 1000 times. Will you get 600, 700 or even 800 heads? It's virtually certain that you won't. The more samples you take, the lower the scatter expressed as a percentage of the number of samples.
Looking at the statistics, we have a total of 19 earthquakes in the magnitude range 7.0 to 7.9 for 2010, as against an average of 15, therefore 4 above average. Look at the year 2006. The total was 9, ie. 6 below average.
Another thing to look for is trends. Are the figures for higher magnitude earthquakes steadily increasing? I can't see any evidence of this. The figures for lower magnitude earthquakes do show an increase because detection methods for this level of earthquake are improving.
In summary, there's no need for any concern as soon as the yearly total jumps one over the average. We would need to see a steady increase in all levels of earthquakes over several years before we might suspect that anything unusual was going on.
Thank you both for the clarification. I have another unrelated question - hope you don't mind.
Do the claims being made in this comment have any merit?
http://www.physicsforums.com/showpost.php?p=2013251&postcount=27
Natalie, no, those claims don't have any merit. If you'll notice that actual thread, instead of just that one message, you'll see that the person who made the claim only had two totals posts. He showed up, spewed some nonsense, posted a link that had nothing to do with his claim, then ran away when the forum regulars challenged him.
He mentions some "conventional scientific basis for the implications of 21-12-2012," then invokes Paul LaViolette. Like so many of the woo artists we deal with here, LaViolette has made some remarkable claims over the years, but he has literally zero data or evidence to support those claims.
In any case, there is no evidence suggesting that Earth is anywhere near the galactic plane, so all of the speculating about what might happen when our planet crosses it in 2012 is based on a presupposition that simply is not true. Earth will not move into or through the galactic plane in 2012. It is true that an increase in dust has been measured across the Solar System in recent years, but there are no ill effects expected from this phenomenon.
Thanks again for the reassuring comments (and sorry if my concerns are somewhat dumb - I know my fear is irrational).
No problem, Natalie, and there's nothing dumb about being concerned.
wouldnt this confirm nasa's snowball earth theory?
wouldnt this confirm nasa's snowball earth theory?
Snowball Earth remains an open question, and the hypothesis was not formulated by NASA. The modern idea goes back about fifty years.
I'm not exactly clear on why you think that dust clouds in today's Solar System "confirm" that our planet was a snowball some 600 million years ago.
Digging two years ago, huh? Hrm.
The theory the good doctor is giving is the "dusty" area of space we are in is causing planetary warming. It's a duo prod at the whole "Global Warming" thing, as well as explaining the other planets 'heating'. I am not sure if every other planet has suddenly warmed (seriously how can we tell with most of them?), but the whole "dusty area of space" thing sounds a little off to me.
With this in mind, connecting all this to that silly hole from three years ago… eh, I dunno. Ultimately, I'm going to ignore all this and point at the one thing that bugs me about that post: The Galactic Plane.
Yes, that thing we're moving away from. I HATE when it's used in an argument, because it's so badly misunderstood. Regardless, that's the silver bullet to this claim. We're moving away, not into, the galactic plane.
Done!
PS: Did you read that whole thread, or did you just stumble upon the single post? Either way, Dr. LaViolette is considered a crackpot by the scientific community because he OPENLY goes against the scientific process with his theories. If that's not a red light to roll your eyes at him… well, yeah.
Stop digging!
I have another question regarding the Yellowstone volcano.
I came across an article on the USGS website -
http://volcanoes.usgs.gov/yvo/publications/2010/10swarm.php
They seem to be suggesting the recent earthquake swarm in 2010 to be nothing out of the ordinary, but isn't it true that swarms have become more frequent there in recent years? I heard about major swarms in 2004 and 2008 - 2009.
Is it possible that those recent swarms mean that Yellowstone may erupt again in the near future? The USGS website said those swarms have been happening for the past 30 years. Does it mean that no swarms have happened there before 1980, and that this is a relatively new phenomenon?
I apologize again for sounding so paranoid - hope you're not annoyed with me.
Natalie
Never apologize for being paranoid hun :) hope you get the answers you are looking for :D
Emmy
Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning.
Albert Einstein
They seem to be suggesting the recent earthquake swarm in 2010 to be nothing out of the ordinary,
That is correct.
…but isn't it true that swarms have become more frequent there in recent years?
As far as I know, that is not true. Who says this?
Scientists do have many more monitoring stations around the world than ever before, so more quakes get recorded, just as I mentioned earlier.
I heard about major swarms in 2004 and 2008 - 2009.
What qualifies as a "major swarm?"
Is it possible that those recent swarms mean that Yellowstone may erupt again in the near future?
If so, then it was also possible for it to erupt at several times over the last several decades. It hasn't.
The USGS website said those swarms have been happening for the past 30 years. Does it mean that no swarms have happened there before 1980, and that this is a relatively new phenomenon?
I really doubt that's the case. Yellowstone experiences thousands of quakes per year, and there is USGS-published data going back as far as the 1920s.
Is it possible that those recent swarms mean that Yellowstone may erupt again in the near future?
Any time a volcano as large as the Yellowstone caldera shows activity, the vucanologists perk up. However, the official analysis is:
There is no evidence that a catastrophic eruption at Yellowstone National Park (YNP) is imminent. Current geologic activity at Yellowstone has remained relatively constant since earth scientists first started monitoring some 30 years ago. Though another caldera-forming eruption is theoretically possible, it is very unlikely to occur in the next thousand or even 10,000 years. Scientists have also found no indication of an imminent smaller eruption of lava.
"Do you ever think about things you do think about?" - Henry Drummond to Matthew Harrison Brady in Inherit the Wind
Thank you both for your reassuring answers, once again. I have another small question, and I promise it to be my last.
I've been reading about Lake Toba recently, and it got me worried.
http://en.wikipedia.org/wiki/Lake_Toba#More_recent_activity
Is there any possibility for this volcano to have another violent eruption in our lifetime? I know there were many major earthquakes there in recent years, but I'm not sure what they mean.
Natalie;
The entire area of Indonesia, including Sumatra, is a massive subduction zone, where the Australia plate is diving under the Sunda plate at a rate of about 2 inches per year. The 2004 Indian Ocean earthquake originated near here.
See http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=43506
The issue at hand is whether Toba could erupt again within our lifetimes… and the answer is "yes" it could. However, the same thing I said above about the Yellowstone Caldera also applies here… eruptions would be preceded by specific kinds of activity, and there would be warning signs. There is no evidence that a large and destructive eruption is imminent. The chances of it erupting in a so-called "supervolcano" eruption in our lifetimes is very, very remote. One of the smaller volcanoes around the caldera could erupt at any time, but then again we have several volcanoes across the world erupting… that's what they do.
I believe that the closest active volcano to me is Lassen… I'm actually not sure if Shasta is still considered 'active', but Lassen erupted (steam and gas) in 1917, I believe. The last time Shasta erupted would have been around 1785 or so.
Do I worry about them? No. Not at all. I'm more worried about earthquakes, and being a Californio I don't worry about them too much. I regard earthquakes as an opportunity to laugh at the tourists.
What I'm getting at is this: You are more likely to as a result of your eating and exercise habits than you are of anything having to do with natural disasters. Natural disasters make the news a lot, but then again they're kind of 'sexy' news items. At http://www.2012hoax.org/doomsday-objects#toc8 we make a point of publishing a table showing the causes of death, worldwide. Top two are heart attacks (6,880,000) and strokes (5,096,000).
Put those together and divide by 365, and you've got over 32,000 people dying every day from these two causes alone.
"Natural Disasters" doesn't even make the list.
"Do you ever think about things you do think about?" - Henry Drummond to Matthew Harrison Brady in Inherit the Wind
Astrogeek,
Thanks for reassuring me. But for some reason, I can't seem to let go of my fear.
Do you know when geologists are estimating Lake Toba is going to erupt again? The only source I could find claims it to be 300,000 - 500,000 years from now, but I'm not sure how reliable their information is.
http://www.andaman.org/BOOK/originals/Weber-Toba/ch3_explosion/textr3.htm
I know you said Indonesia is an area with many earthquakes, but how can you be sure some of these earthquakes are not signs of an impending eruption?
Well, I'm not a geologist or vulcanologist, but I do know that the kinds of earthquakes that result from fault lines moving are different than the earthquakes that result from magma moving.
I'll have to defer to the USGS and the Q&A page about the Docudrama "Supervolcano" that aired on the Discovery channel a few years ago:
http://volcanoes.usgs.gov/yvo/publications/2005/docudrama.php
One of the key passages is:
Such a giant eruption would have regional effects such as falling ash and short-term (years to decades) changes to global climate.
(emphasis added)
So, unless you plan on moving to Indonesia and building a house on the slopes of Toba, the chances of a full-scale Supervolcano eruption of Toba killing you or anyone you know is tiny.
"Do you ever think about things you do think about?" - Henry Drummond to Matthew Harrison Brady in Inherit the Wind
But isn't it true that the previous eruption of Toba nearly lead to the extinction of the human race?
http://en.wikipedia.org/wiki/Toba_catastrophe_theory
Do you suppose 300,000 - 500,000 years is a fair estimation for the next eruption? Because I've searched for information regarding this issue, and this was the only estimation I could find. The author mentions it at the end of the page.
http://www.andaman.org/BOOK/originals/Weber-Toba/ch3_explosion/textr3.htm
Well, we go by a theory that isn't supported largely by the scientific community. Okay, sure. Let's go with it.
Two major things to consider.
1) Health Care back then for humans.
2) Technology back then for humans.
We are largely more able to do deal with natural causes, so sickness from cold isn't nearly as devastating. Additionally, we have ways to heat things up, be it ourselves, our homes, and so on.
I welcome a volcanic winter, personally. I want snow.
Hi Natalie;
The idea that the Toba eruption created a bottleneck in the human genome was advanced a while back. I think that it is not well-accepted.
As far as an estimation of the next one, yes I think those are 'fair', but again, I am not a geologist or vulcanologist, so what I think has very little meaning. :-D
"Do you ever think about things you do think about?" - Henry Drummond to Matthew Harrison Brady in Inherit the Wind
Under the 'Eruption Propect' bit of the Lake Toba Wikipedia page says:
"The 2004 earthquake physically rolled the Sumatran island and altered the shape of the Earth as was detected by the GRACE satellite. Recent highly-localized earthquake activity may initiate magmatic activity of this colossal global climate modifier."
Can earthquakes actually cause eruptions then? And if so, shouldn't we be worried, since there are so many around that area? Or could 'magmatic activity' mean an eruption of one of the smaller volcanoes you mentioned?
Every earthquake, by definition, "[alters] the shape of the Earth." Major quakes obviously result in more noticeable changes than smaller quakes.
Volcanic activity can cause earthquakes, but I don't know how strong correlations are going the other direction. There is some evidence that large quakes can cause an uptick in regional volcanism.
There have always been lots of quakes and uplift in the Lake Toba area, as is the case with Yellowstone and other calderas. Why would you worry?
