Full moon fear for Mayon volcano

[Thing]

http://news.bbc.co.uk/1/hi/world/asia-pacific/5258806.stm

Scientists in the Philippines have warned that Wednesday's full moon could spark a major eruption of the Mount Mayon volcano.

Experts say Mount Mayon, the most active volcano in the Philippines, could erupt at any time.

But the full moon's gravitational pull could trigger the eruption, they say.

A full moon coincided with at least three of Mayon's 47 eruptions, including the two most recent ones in 2000 and 2001.

Can this possibly be relevant?

[andyandy]

i hope they've got more evidence for that than

A full moon coincided with at least three of Mayon's 47 eruptions, including the two most recent ones in 2000 and 2001.

:D

[sphenisc]

This suggests there may be a link.

http://vulcan.wr.usgs.gov/Outreach/AboutVolcanoes/do_tides_affect_volcanoes.html

[andyandy]

Who would have thought that the moon had that kind of power, not only to be able to cause the world's oceans to bulge, but also to squeeze terra firma twice a day? But it does, so it should not come as a complete shock that reputable scientists have suggested that these squeezings might influence whether a volcano will erupt or not.

The idea is that if a volcano is full of magma, the squeezing at the fortnightly tidal maximum might be just enough to overcome the resistance of the crust, push magma out, and get an eruption going. Once started, the eruption would continue on its own.

More than 25 years ago, a pair of earth scientists compared the records for 680 eruptions that occurred since 1900 and found that "the probability of an eruption is greatest at times of maximum tidal amplitude." In plainer language, volcanoes are more likely to erupt at the fortnightly (or 14-day) "high" tide.

A specific look at 52 Hawaiian eruptions since January 1832 shows the same sort of pattern. "Nearly twice as many eruptions have occurred nearer fortnightly tidal maximum than tidal minimum." HVO scientists have noted that the Pu'u 'O'o fountaining episodes each occurred remarkably close to fortnightly tidal maximums and that the first set of eruption pauses in 1990 (periods where the eruption turned off for up to a few days) occurred remarkably close to fortnightly tidal minimums.

well i never.....:)

[wollery]

Yep, makes a lot of sense that such a phenomenon would coincide with the maximum gravitational differential pull of the Sun and Moon.

[Cuddles]

Sounds fairly reasonable. Shame they didn't provide any further information to distinguish this from the woos.

[Correa Neto]

Form the site http://vulcan.wr.usgs.gov/Outreach/AboutVolcanoes/do_tides_affect_volcanoes.html
Although this is a fascinating correlation, there are just too many tidal maximums and too many volcanoes to base predictions on tidal cycle alone. In the Hawai'i example of 52 eruptions since January 1832, there have been nearly 3,900 tidal maximums, of which roughly 3,850 of them went by without causing an eruption. Statistically, this is about a one percent chance that any tidal maximum will affect the start of an eruption.

The correlation is more important as a clue to how volcanoes work. The effect of the tides suggests that a volcano can remain in a state of near eruption for a period of time before some threshold is exceeded and an eruption starts. There are probably many possible mechanisms for exceeding that threshold - the lunar tides are but one.

Bolds are mine.
Sounds like someone has uhmmm... How can I say.... Added some spice to the topic.

[Meffy]

Added some spice to the topic.
Without a subtle touch of spice, Mayonnaise is boring.

[Hellbound]

Without a subtle touch of spice, Mayonnaise is boring.

A theory just isn't a theory without the tangy zip of Miracle WhipTM!

[Meffy]

=>_<= ... on Velveeta. The two belong together.

"May God bless and keep the Czar^H^H^H^HMiracle Whip and Velveeta... far away from me!"
-- Not Quite Fiddler on the Roof

[Wolverine]

See: Mooning a volcano (http://www.badastronomy.com/bablog/2006/08/09/mooning-a-volcano/), written by some guy named Plait.

[AK-Dave]

There are a lot of people who claim that earthquakes are also influenced by lunar cycles. I have done an extensive analysis and determined there is a lot of truth to this. According to my calculations, more than 90% of all earthquakes occur within 15 days of a full moon.

-David

(edited for typo)

[Meffy]

Jupiter's moon Io definitely suffers from tidal forces -- they crack its crust right open regularly, making it (IIRC) the most geologically active object in the Solar System. (Unless you count the Sun! :-D)

Our own Moon doesn't exert anything like that kind of force on Earth though.

@AK-Dave: It's True! Same goes for New Moon. How mysterious!

[Correa Neto]

[annoying OT nitpicking]
Can we really talk abot a star's geology?
[/annoying OT nitpicking]

[Meffy]

Just so. That's why I put it in parenthetical disclaimer form.

[AK-Dave]

@AK-Dave: It's True! Same goes for New Moon. How mysterious! If we are going to consider the influence of the New Moon, I think we could safely say that more than 90% of all earthquakes and volcanic eruptions occur within 7 days of a full or new moon. Now that's spooky!

[Meffy]

* Meffy plays eerie music on the keyboard... =@.@=

[Dark Jaguar]

I should look into this, but maybe one of you could answer this quicker. Why would the moon being fully illuminated from our point of view have an affect on how much of a gravitational pull it has?

[Wolverine]

It's not just the appearance of the lunar phase itself nor the quantity of reflected photons. ;)

During new and full Moon phases, the gravitational influences of the Moon and the Sun are aligned on the same axis, resulting in a combined (greater) tidal influence on the Earth. This page (http://tidesandcurrents.noaa.gov/restles4.html) at the NOAA (even though its focus is more on things nautical than astronomical) has a couple of handy diagrams and explains the geeky details better than I.

Mmm, syzygy.

[wollery]

Heh, syzygy is my favourite word!

[andyandy]

intresting link, but the writer over-stretches a little with his conclusions

First, Mayon is a very active volcano. It has quakes, minor explosions, lahars (mud flows) and such all the time. Certainly some will coincide with the full and new Moon. Let’s be generous and say that the time period around the full Moon is 2 days: a day before and a day after. The Moon goes through a complete cycle in roughly 29 days, so it’s full for 2/29 = 1/15th of the time. If you then look at 47 eruptions, then you expect to see 47/15 = 3 eruptions near the full Moon. And hey, that’s exactly what the report says!

So, statistically speaking, the Moon has nothing to do with eruptions. If it did, you’d expect to see a bump in the number of events near the full Moon. But the number of eruptions near the full Moon is what you’d expect from random chance. In other words, on average it doesn’t matter if the Moon is full, new, first quarter, or whatever. Now to be fair, the article doesn’t say how big a time period they used around the full Moon. Maybe they only used one day, not two. Even then, the correlation would be weak, because 47 eruptions isn’t a big enough sample to choose from. It’s small number statistics, like flipping a coin three times and having it come up heads each time. It’s rare, but it does happen on average one out of every eight times. You need bigger samples to get good statistics.
http://www.badastronomy.com/bablog/2006/08/09/mooning-a-volcano/
(bold added)

He seems to have committed the same mistake as those he's critizing....namely relying on a very small sample size to draw his conclusion that "statistically speaking, the Moon has nothing to do with eruptions."


To be fair he later adds

So I am not totally discounting a connection between the Moon and this volcano, but I am saying that at best such a link is very weak, and probably not worth worrying about.

but even this conclusion is based on a sample which he's already dismissed as being too small to be of much value.....

[Meffy]

Heh, syzygy is my favourite word!
It's a good one for checking how inclusive small dictionaries are. "Neaping" is a related good'un.

What Wolverine says is right -- the illumination is just a by-product of the spatial alignment which causes tidal forces of sun and moon to work together. Whether this has any significant effect on small bodies of liquid such as a volcano's magma source... that's another matter and I don't think it's known at present.

[Ladewig]

It's a good one for checking how inclusive small dictionaries are.


I prefer using "pyrrhic" for that task because it is so easy to find. Open the dictionary to the beginning of Q and look on the previous page.

[Dark Jaguar]

Thanks. Syz... dang I can't even read that word straight, much less pronounce it.

[Meffy]

Just remember Moe the Bartender from The Simpsons -- his last name is Syzlak -- and Iggy Pop, whose first name, mispronounced and misspelled, is Ygy.

See? It's Simple When You Know HowTM.

[edit] Wikipedia claims, but lacks a citation for, the following:
Syzygy is the shortest English word with three ys, as well as longest word in the English language from which no other words or phrases can be formed by rearranging its letters (i.e. the word can produce no anagrams).

I think it's pronounced "SIZZ-ih-jee" but use it but rarely so am not certain of that.

[The Bad Astronomer]

I may have overstated the case in the way I phrased the blog entry. From the statistics they themselves quote, no conclusions can be drawn, since 3 eruptions are what you expect from random chance. However, they are the ones fretting about the Moon's phase, when there is nothing there to support it.

Also, they ignored the phase when the Moon is new. This actually would double the sample of "times the Moon would affect the volcano". In fact, you should see fewer eruptions at first and third quarter, when tides are minimized (unless flexing is the problem, and then you need ot look at the times between new and 1st quarter, etc). With all this, the best they could come up with was 3/47?

So it still seems to me that there is no obvious correlation between the Moon and eruptions, even with that small a sample. But as I said in the entry too, I cannot discount it. It just seems to be the most likely thing to do.

[Dark Jaguar]

Just remember Moe the Bartender from The Simpsons -- his last name is Syzlak -- and Iggy Pop, whose first name, mispronounced and misspelled, is Ygy.

See? It's Simple When You Know HowTM.

[edit] Wikipedia claims, but lacks a citation for, the following:


I think it's pronounced "SIZZ-ih-jee" but use it but rarely so am not certain of that.

Okay. Now how do I remember those esoteric bits of information? That's the problem with me. Mneumonic devices don't work very well because I have trouble remembering the device. I end up having to just do the old fasioned "brute force" memory methods. I never did use the my mother... something about a sandwitch... thing for memorizing planet order, I did it manually, with this! *holds up soldering iron*

[Skeptic Ginger]

Westward Tidal Lag as the Driving Force of Plate Tectonics (http://www.gsajournals.org/gsaonline/?request=get-abstract&doi=10.1130%2F0091-7613(1973)1%3C99:WTLATD%3E2.0.CO%3B2)

The abstract suggests "that the westward transport imparted during each tidal cycle is as much as 0.3 mm."

If you think about the Moon's tidal force on a large lake, you don't see much of a tide. I doubt there is significant force on a magma chamber compared to the other forces involved, namely the rocks, gases, and plate movements affecting the magma chamber.

While it seems logical, don't forget how small gravitational forces are. As big as the Earth is, I can still lift an object against the Earth's gravitational force with my little arm muscles. You are talking about breaking the solidified magma plug in the volcano throat here.

[andyandy]

I may have overstated the case in the way I phrased the blog entry. From the statistics they themselves quote, no conclusions can be drawn, since 3 eruptions are what you expect from random chance. However, they are the ones fretting about the Moon's phase, when there is nothing there to support it.

Also, they ignored the phase when the Moon is new. This actually would double the sample of "times the Moon would affect the volcano". In fact, you should see fewer eruptions at first and third quarter, when tides are minimized (unless flexing is the problem, and then you need ot look at the times between new and 1st quarter, etc). With all this, the best they could come up with was 3/47?

So it still seems to me that there is no obvious correlation between the Moon and eruptions, even with that small a sample. But as I said in the entry too, I cannot discount it. It just seems to be the most likely thing to do.

fair enough....:)

the BBC article was pretty thin on its facts....the article on http://vulcan.wr.usgs.gov/Outreach/A...volcanoes.html suggests there may be some correlation between the moon and eruptions....but to look at that data and then say
that Wednesday's full moon could spark a major eruption of the Mount Mayon volcano.
is rather silly.