Astroblog

There is still widespread angst that comet 2010 X1 Elenin will cause significant earthquakes when it comes close to Earth later this year.

I’ve shown previously that Elenin is not associated with earthquakes, however, in the comments (and on the intertubes), an as yet unpublished paper by Mensur Omerbashich titled “Astronomical Alignments as the Cause of ~M6+ Seismicity” http://arxiv.org/abs/1104.2036 is referenced. The paper purports to show that astronomical alignments, particularly that of Elenin, are the proximal cause of earthquakes of magnitude 6 or stronger. To save you time before you read the paper and my critique of it, I’ll give you a short and long summary.

Short Summary: It’s nonsense on stilts.

Longer Summary: A sloppy paper which presents incorrect data. It ignores basic information on comets, basic physics and its “evidence” is drawing lines thorough planets.

The idea that gravitational influences could alter the frequency of earthquakes is plausible. The tidal bulge in the Earth (as opposed to the tidal bulge in the ocean) is about 30 cm, and a periodic flexing of the crust by 30 cm could indeed trigger earthquakes. Indeed, there is a weak correlation between the lithospheric tides associated with Full/New Moon and a subclass of shallow earthquakes (increasing the probability of this subclass of earthquakes by less than 1%).

On the 27th of February 2010, Elenin was beyond the orbit of Jupiter, but it is claimed that it had more tidal effect than bigger comets and asteroids closer to Earth.

However, tidal force drops of as the cube of the distance. The Sun is much more massive than the Moon, but the Moon has a bigger effect on Earth's tides because it is so much closer.

Venus has around the same mass as the Earth, and is the closest planet to us, but it produces roughly on ten millionth of the tidal force on Earth than the Moon does. If the Moon is not very effective at producing earthquakes, Venus sure won’t be (and invoking electrical or magnetic forces won’t work either, they fall off rapidly with distance too).

To assert that planetary alignments are a significant influence on earthquakes you will need some pretty strong evidence, does this paper supply it?

XKCD sums up the problems with the paper.

Coma confusion: You know the paper is not going to go well when it starts off with “..[Elenin] drags with it a cloud of gravitational locked particles around 30,000 Km across, making its gravitational shadowing significant …[page 1 para 4]”. Leaving aside the question of what “gravitational shadowing” is (it is never defined), Dr. Omerbashich is describing the coma of comet Elenin.

However, the coma is by no means “gravitationally locked” the particles in the coma are only loosely bound and are readily lost, the coma only appears stable because new dust particles are currently being added by outgassing from the comet.

Indeed, as I type Elenin’s coma is dispersing, as its dust production rate has dropped (possibly due to having exhausted a layer of volatiles, eg frozen carbon dioxide, below the comets crust). Also, while the coma is thick by interplanetary standards, from the point of view of Earth the coma is still a pretty good vacuum, with negligible mass compared to the parent comet.

Not only that, a coma is a feature of all comets that approach the Sun closely, for example comet 81P Wild had a coma of 50,000 Km and 103P Hartley had a coma of 150,000 Km. Because the coma is dynamic, produced as a comet heats up, at the early time points Omerbashich considers, Elenin’s coma would be much, much smaller.

Source: Wikipedia Commons.

What’s missing? The first thing that stands out when you read the paper is what is missing. All the classical planets, as well as Uranus and Neptune, are considered along with comet Elenin. But it’s obvious what is missing.

Where are all the Main Belt Asteroids? If you are going to consider a 4 Km wide frozen snowball, then large chunks of real estate like Ceres, Vesta (529 Km in diameter), Pallas and Juno should be considered as well.

And what about the 46 comets that reached perihelion in 2010, especially comets comparable to Eleinin such as Comet 81P wild, a comet of 4 km diameter with a 40,000 km coma, that came within 1.2 astronomical units (AU) of earth and comet 103P/Hartley, a 2 Km diameter comet with a 150,000 Km coma that came within 0.13 AU of Earth? Why aren’t they included if Elenin, which was more than 6 AU away for most of the year, is?

What’s also missing is the Moon, mostly. There are a few lunar alignments shown, and 14 of the 24 Full and New Moons are marked in table 1, but as the Moon is the closest, most important tidal object in our sky, the complete lack of 10 lunar encounters is significant.

Figure failure Figure 1, (section B shown below) purports to show the “resonance magnification pattern” as a “gravitational shadow” traverses the Earth.

What it in fact shows is a series of graphs of earthquake magnitude vs time. Each quake is shown equidistant from the others, regardless of the actual time separation between them. As well several points are left out, this greatly distorts the actual data.

For example graph B of figure 1 shows the series of earthquakes from 10 January to 12 January. It looks like a smoothly rising curve (possibly correlated with the “gravitational shadow”, whatever that is). However, only one magnitude 5.1 quake is shown, whereas there were many 5+ quakes in this time period. Also, the time point of 11 January is omitted even though there were no quakes of 5+ in this period of time (the other graphs have similar issues). This makes the curve look quite different from reality.

This graph shows how it should have been done (click to embiggen). I have plotted quake magnitude vs Julian Day number since 8 January for the interval between 9 January and 14 January, (full Julian day numbers make the graph unreadable), UT times of earthquake occurrence being rounded to the nearest half hour for conversion to Julian dates.

During these dates Venus was a degree or closer to the Sun (Omerbashich never really gives a numerical criterion for what constitutes an alignment). I have also plotted the tidal force due to Venus at the time of each earthquake (Calculated from the formula below using Excel, planetary masses and distances from SkyMap and earthquake magnitude from here), it is falling over this period as Venus is moving away from the Earth.



You can see that this graph is very different to the one that Omerbashich provides, and refutes Omerbashich’s claims. Now this is just one graph out of a whole bunch, but each one has similar, fatal flaws. They all show M+6 events evenly spaced, regardless of when they occurred, and omit relevant 5+ events. When a 5+ event is included, it is to anchor a graph and give a misleading impression of a smooth curve.

As the tidal effect is actually due to the Sum of the tidal force of Venus and the Sun, I also show a graph with the Sum of the Venus Sun tidal forces (again, click to embiggen). You can see that they are going down. This is mostly due to the earth moving away from the Sun post perihelion, as the tidal force of Venus is one ten millionth of that of the Sun, it doesn’t register in this graph.

Statistics revisited Table 2 of the paper purports to show all M6+ earthquakes in relation to various alignments (it doesn’t, but the discrepancies are minor, just an example of sloppiness). It looks kind of impressive, until you think about it. All Omerbashich is doing is lining up instances of events with earthquakes. Using this method I can show that my family eating pizza causes earthquakes.

On March 4 I had pizza, and there was a M6.5 Earthquake, and again on March 11 (an impressive M6.9 quake) and on March 25 (only M6.6, but there was an M7.5 earthquake when we had pizza on June 16). All in all, 20 times when we had Pizza there was a magnitude 6 or greater quake (actually, we had pizza more times than that, but those are the times that I have dates and UT times for).

Apart from the physical implausibility of my family chowing down on pizzas causing earthquakes (well maybe my increase in weight could do it), how can we determine if eating pizza causes earthquakes? Statistics is how.

In 2010 there were 156 earthquakes of magnitude 6 and over. In 2010 we had pizza 48 times. If the earthquakes were occurring at random with respect to our eating pizza, then we would expect an M6+ earthquake to occur on a day we ate pizza 21 times, and we observed 20 earthquakes on days we ate pizza. Therefore we can conclude there is no connection between us eating pizza and earthquakes (physical implausibility aside).

So, what about the planetary alignments and the earthquakes? The most plausible astronomical source of earthquakes is the Moon, which causes the strongest lithospheric tides. There were 24 full or new Moons in 2010. This is where the Sun and Moon are aligned and we get the strongest tides, which might have a chance of producing earthquakes (or triggering ones that were just about to go anyway).

In 2010 there were 12 earthquakes that corresponded to a full or new Moon. By chance alone, we would expect 10 earthquakes to correspond to the full or new Moon, which is not significantly different from what we observe. We can do a double check, if the alignment idea is correct, then there should be more earthquakes during the full/new Moon (when the tides are highest) than during first and last quarter (where the tides are lowest).

In fact there were 16 earthquakes during first and last quarter Moons compared to 12 during full/new Moon. Thus the idea that lunar alignments are a significant source of earthquakes is disproven. Actually, e have one more trick up our sleeve, I took all M6+ earthquakes from 2000-2010 and did a Fourier transform on it. If the Moon played a significant role, we should have seen a peak corresponding to the interval between full and new Moons. But we don’t, or any other peak corresponding to an astronomical alignment.

This pretty much eliminates all evidence of astronomical alignments playing a significant role in earthquakes.

Omerbashich spends a lot of space on alleged Elenin alignments, but it's just the pizza gambit again. The plausibility of Elenin being responsible for any earthquakes is very low. If the Moon can’t produce significant numbers of earthquakes above baseline activity then Elenin, with a tidal force of less than a billionth of that of the Moon, is not a plausible candidate for producing earthquakes. Again, completely ignores comet 81P (which had a thousand times more tidal force than Elenin) and comet 103P/ Hartley (which had a million times more tidal force than Elenin at its closest approach to Earth). 103P is pretty much devoid of association with earthquakes.

The rest of the paper is pretty much cherry picking figures. Figure 2 basically shows that the occurrence of M8+ earthquakes is pretty random, but Omerbashich claims this shows that comet Elenin (a 4 Km chunk of dirty ice) has been influencing earthquakes since 2007 (when it’s tidal force was a trillionth of that of the Moon). Yet somehow, mysteriously all the other, closer comets (including much bigger ones, like 2006 P1) had no effect.

Conclusion Omerbashich’s paper, “Astronomical Alignments as the Cause of ~M6+ Seismicity” is a poor paper, with inadequate and misleading data analysis, and which misunderstands basic physics and cometary nature. It provides no evidence that Elenin is involved in earthquakes.

Postscript: at this site, it was claimed that planetary alignments as predicted by Omerbashich would produce big earthquakes on 23 May 2011, 23 (and 24) May have come and gone, with only a couple of magnitude 5 quakes, fairly quite days really. Dr. Omerbashich's web site claims 9-19 May as a time of intensified 6+ quakes. It wasn't.

Post-postscript: I've beening trying to think of a really simple way to get the scale differences between Eelnin and the other objects in the solar system that people can grasp easily.

Dr. Omerbashich likens his resonator effect to that of a group of soldiers marching in lockstep across a bridge, causing damaging resonances in the bridge. Well, imagine the Moon is a 70 Kg soldier marching along, behind the soldier is an ant marching. Do you think the ant will add to the resonance produced by the soldier? No, the mass of the ant is far too small. AND that ant is 10 times more massive in relation to the soldier than Elenin is to the Moon.

Disclaimer:  small portions of the original paper, less than 1% of that work, are quoted with appropriate citation and links to the original  under the fair use provisions of the copyright act for the purpose of criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research.

Labels: comets, Pseudoscience