Posted by: Barry Bickmore | May 9, 2017

Do Earthquakes Create Volcanoes?

This is part of a series of articles responding to the claims made in Dean Sessions’ Universal Model.  Click the link to see the introduction to the series.

Do Earthquakes Generate Heat?  Yes.

Given that Dean Sessions, author of the Universal Model (UM), believes a giant ice ball is in the Earth’s core, geothermal gradients are problematic.  That is, as far as we can drill down, the temperature generally keeps getting hotter the deeper you go, so it seems unlikely that the Earth would be cold enough in the center to sustain an ice ball.  Sessions maintains that the crust of the Earth is really hotter than the deep interior because tidal forces cause earthquakes in the crust, and frictional heating along the earthquake faults melts the surrounding rock, which can then be ejected out of volcanoes.  In another post (see Facepalm:  the UM and Radioactive Lava), I explained why, even if the source of heat in the Earth is near the surface, the center would still heat up until the temperature is at least as hot as the outer shell where the heat is being generated.  So even if Sessions is right about the origin of heat to generate volcanic activity, his ice core idea won’t work.  Is there some way to also test his idea that frictional heating during earthquakes generates volcanic activity?  Read on.

In an earthquake, strain energy is suddenly released when the Earth cracks and the rocks on both sides of the crack (fault) slide past each other.  (Breaking a stick in your hands provides a good analogy.  When you start bending a stick, strain energy builds up, until finally the wood breaks and the two strained halves snap back so they aren’t bent anymore.  This releases the strain energy mainly as vibrations.)  Geophysicists measure the seismic waves (vibrations in the Earth) generated by earthquakes, and can calculate how much strain energy was released by the quakes.  Some of the strain energy may also be dissipated to deform and crack rocks, or as heat generated by friction as the two sides of the fault slide past each other.  This may, in fact, be enough to melt some of the surrounding rock.  Sessions quotes a number of geologists saying as much (see UM, section 5.3).

Is it Enough Heat to Cause Volcanism?  Almost Certainly NOT.

Here’s the problem with frictional melting, though.  Once it starts, the presence of melted rock reduces the friction, so that less of the strain energy subsequently released can be turned into heat energy.  Get it?  If melting occurs, the fault is lubricated so that it becomes much harder to create enough frictional heat to cause more melting.  Therefore, it seems very unlikely that friction from earthquakes could cause rocks to melt on a scale large enough to contribute to volcanism.

It’s tricky business trying to estimate how much frictional heating occurs during an earthquake, but luckily, someone has gone to the trouble of doing some very difficult measurements to estimate it for one of the largest earthquakes ever recorded.  Several months after the 2011 Tohoku earthquake (the one that caused the tsunami that wrecked the Fukushima nuclear reactor) a group of Japanese and American scientists took a drilling ship out to where the earthquake originated, drilled down through the fault, and then put temperature sensors down there to measure how much frictional heat from the earthquake was left over, and how fast it was dissipating through the surrounding rocks.  That way, they could estimate how much heat was originally released.

The scientists say this 0.31 temperature anomaly corresponds to 27 million joules, or 27 megajoules, per square meter of dissipated energy during the earthquake. A joule is the amount of energy required to produce one watt of power for one second. The “friction coefficient,” or the resistance to relative motion between the blocks, was surprisingly small at 0.08, the scientists point out.

“One way to look at the friction of these big blocks is to compare them to cross-country skis on snow,” Harris said. “At rest, the skis stick to the snow and it takes a certain amount of force to make them slide. Once you do, the ski’s movement generates heat and it takes much less force to continue the movement.

“The same thing happens with an earthquake,” he added. “This is the first time we’ve been able to calculate how much frictional resistance to slip there is. This has never been done before in nature – just in the laboratory.”

I did some back-of-the-envelope calculations, and figured out that there was enough heat generated in the Tohoku quake to melt a layer of rock along the fault no more than about 1 cm thick.  That’s enough to lubricate the fault, but not nearly enough to cause volcanic activity.

Now, the Tohoku earthquake had a magnitude of 9.0-9.1, which is the fourth highest ever recorded.  On the moment-magnitude scale, a jump of two points amounts to 1000 times as much seismic energy released.  That got me thinking.  According to Byerlee’s Law, almost all rocks have about the same coefficient of friction during slippage, so it’s probably safe to say that earthquakes with larger magnitudes must generally release more frictional heat than those with smaller magnitudes.  If heat flow up from the crust is primarily from earthquake friction, I reasoned that areas with the most heat flow should be the same areas where the most earthquake energy is released.

To test this idea, I downloaded (see the Advanced National Seismic System catalog) location, date, and magnitude data for every recorded earthquake with magnitude 3.0 or greater for the period 1960-2016.  Then I calculated the relative seismic energy released for each event and added them up over a 2° latitude-longitude grid, and divided the total for each grid cell by the surface area in the cell.  That way, I got a map of how much seismic energy had been released per unit surface area over the entire globe.  The following map is the result, where the color bar indicates the relative amount of energy released on a base-10 logarithmic scale.  Every unit on the scale indicates a factor of 10 increase, so a 1-point difference represents a 10-fold difference in energy, and a 2-point difference indicates a 100-fold difference, etc.  I’ve also plotted outlines of the world’s land masses for reference.

EarthquakeEnergy

Now compare that with the U.S. Geological Survey’s map of measured heat flow from the crust, which Sessions uses as Figure 5.4.5 of his book.

Fig5_4_5

Sessions claims,

The hottest areas on the Actual Heat Flow map correspond to plate boundaries-right where the greatest amount of gravitational friction occurs. (UM, Vol. 1, p. 92)

In other words, he thinks that tidal forces from the Moon make the most movement happen at tectonic plate boundaries, causing the most heat to be generated there.  But that’s clearly not true of all plate boundaries.

Here’s a map of the tectonic plates, with arrows showing their relative motion.  Comparing this with the two maps above, it’s clear that greater than average numbers of earthquakes occur at all plate boundaries, but higher than average heat flow mainly only occurs at a particular kind of plate boundary:  divergent boundaries, and to a lesser extent at subduction zones.

Tectonic-plate-boundaries

Plate Tectonic theory divides the plate boundaries into different types:  divergent zones (mid-ocean ridges, where the plates are pulled apart and new ocean crust is created), subduction zones (oceanic crust from one plate gets shoved under another plate), continental collision zones (two chunks of continental crust run into each other and push each other upward), and transform boundaries (plates slide horizontally past each other).  While high earthquake activity occurs at all types of plate boundaries, there is only high volcanic activity at mid-ocean ridges and above subduction zones.  This is thought to happen because there are reasons for the underlying mantle rock to melt there more than in other places.  At mid-ocean ridges the pressure on the underlying rock is lowered, making it easier to melt, and at subduction zones the subducting oceanic plate carries water down into the mantle, which also lowers the melting temperatures of rocks.

But in the Universal Model, what reason is there for earthquakes at some plate boundaries to produce extra volcanoes and heat flow, but not at others?  I haven’t been able to find any.  (Maybe the UM Team will speak up and tell me if I missed it?)

Let’s compare some of the areas with the highest seismic activity.  The Himalayas are in a continental collision zone, where two chunks of continental crust are smashing into each other.  In my seismic energy map above, the density of seismic energy released in the Himalayas is only about a tenth of what we find at subduction zones, where both extra seismic and volcanic activity occur.  However, the seismic energy released in the Himalayas is about ten times what we find at the mid-ocean ridges!

If there is about 10 times as much seismic energy released in the Himalayas as on the mid-ocean ridges, why are the mid-ocean ridges essentially a 40,000-mile long string of volcanoes with the highest heat flow through the crust, whereas very little volcanic activity occurs in the Himalayan region, and the local heat flow is very low?

If there is about 100 times as much seismic energy released in subduction zones as in mid-ocean ridges, why is the heat flow so much higher around the mid-ocean ridges?

Dean Sessions notes that volcanic eruptions are associated with swarms of small earthquakes, however, so what if a large number of earthquakes were spaced closely together?  Could that generate enough heat to melt the surrounding rocks?  The problem is that earthquakes associated with volcanic eruptions are typically quite small–the largest having magnitudes of about 7, but only rarely more than about 5.  How many magnitude 5 earthquakes would it take to release the same amount of energy as the Tohoku earthquake that was magnitude 9?  A million.  Yes, one million, and the fact is that most earthquakes associated with volcanic activity are much weaker than magnitude 5.  However, when the heat flow was measured around the Tohoku fault, it turned out that only a relatively small amount of melting could have occurred.

[NOTE:  Geologists think these small earthquakes are associated with magma movement. For example, if there is some molten rock in a crack, what happens to the crack of the melt moves upward?  The void space would collapse, causing an earthquake.  This would have to happen no matter how the magma was generated.]

Black and White Thinking

Hopefully it is now clear why Sessions can quote geologists saying that 1) some frictional melting can occur, 2) it’s hard to tell exactly how much frictional heat is generated in earthquakes, BUT 3) frictional melting along faults has never been considered a serious contender for the main cause of volcanism, because there are good reasons to believe it couldn’t possibly melt enough rock to explain volcanoes.  So how did Dean Sessions come away with such a different message from his sources?  The answer, I believe, is that he is the kind of person who is incapable of nuanced thinking, at least when it comes to subjects he cares about.

Although Sessions occasionally says something polite-ish about scientists, he much more frequently portrays scientists as a bunch of bumbling, confused morons who can’t stop trying and failing to shove the square pegs of the facts into the round holes of their theories.  But time and again, it turns out that it’s Sessions who doesn’t seem to be able to process information that goes contrary to his ideas.

Consider, for example, how he interacts with a 1998 article published in Science magazine.  Sessions first suggests there is some kind of unspoken taboo against geologists even discussing the possibility of earthquakes causing volcanism.

If modern geology recognized the possibility that earthquakes were causing, or at least contributing to volcanic eruptions of molten extrusive lava, one would think there should be extensive studies on the matter, and with such studies would come the knowledge of just how much frictional heat actively moving faults generate. Additionally, the more the geologists know about frictional heat from seismic activity, the less inclined they would be to dismiss it. Surprisingly little detail exists when researching those who published journal articles discussing frictional heating via faulting. It seemed almost as though there was a “don’t go there” attitude;–as if they were saying “we already know the heat comes from magma” so why look elsewhere? (UM, Vol. 1, p. 79)

To make his point, Sessions immediately introduces us to the Science article, entitled “Frictional Melting During the Rupture of the 1994 Bolivian Earthquake”.  Wait… I thought he was supposed to be showing how it’s verboten for geologists to discuss… exactly what’s in the title of this paper published in the most prestigious science journal around….  Okay, never mind.  Let’s just see what he quotes from the article.

“The possibility of frictional melting during faulting has been suggested by several investigators.”  (UM, Vol. 1, p. 80)

Huh?  So there were more geologists discussing the possibility of frictional melting, even before that article was published?  Uh… let’s just move on and see what Sessions has to say about it.

Perhaps at that time, it stretched the imagination too far to suggest the possibility that friction might be the cause of melting because few actual measurements of heat generated in faults had been taken.   (UM, Vol. 1, p. 80)

How, may I ask, does saying that several scientists have suggested a certain possibility support the idea that “it stretched the imagination too far to suggest the possibility”?

Moving on….  Sessions quotes some other geologists saying this isn’t a simple problem to solve.

The problem of heat generation on fault surfaces has yet to be satisfactorily resolved. It appears likely from the above discussion that different faults may exhibit different behavior in this respect, perhaps because of different degrees of lubrication related to pore-fluid pressure. As numerical modeling techniques improve, and more heat flow data are collected from the vicinity of large faults, the question may be answered. However, for now there is no simple solution as to how much frictional heat is generated by faults.  (UM, Vol. 1, p. 80)

Well, at least that makes sense.  We need to do a lot more heat flow measurements, like they did with the Tohoku quake, to get it all figured out.  [Note:  These measurements can be VERY EXPENSIVE, so it shouldn’t be a huge surprise that we could use more of them.]  But then Sessions moves back to the 1998 Science article.

From the Science article previously cited, researchers recognized significant heat generation during a seismic event in Bolivia, in 1994:

“The amount of non-radiated energy produced during the Bolivian rupture was comparable to, or larger than, the thermal energy of the 1980 Mount St.. Helens eruption and was sufficient to have melted a layer as thick as 31 centimeters.”

The enormous 1980 Mount St. Helens eruption, compared by some to an atomic blast, generated an immense quantity of heat energy, so why is it that questions remain unasked about how heat impacts melting during earthquake events? Is this an important factor or not? Here is the response from the same journal article:

“These studies indicate that frictional melting can occur if the stresses involved in faulting are sufficientlhigh. Despite these studies, frictional melting is not generally regarded as an important process during earthquake faulting because of uncertainties in the stress levels….”

Amazingly, these scientists observed an astonishing amount of heat generated in the fault area of the Bolivian quake where the melted thickness was only 3.7 mm:

“If the thermal penetration depth, Delta d = 3.7 mm, is used, the local temperature rise is of the order of 52,000 Celsius.”  (UM, Vol. 1, p. 80)

Stupid scientists!  Well okay, before getting all judgy maybe we should look at the next sentence in the article to see if they give any reason why they don’t consider frictional melting to be all that important.

 Sibson noted that production of pseudo-tachylyte (glassy material presumably formed by frictional melting) should take place during faulting, but very few faults contain pseudo-tachylyte.

Hey, doesn’t Dean Sessions claim that melted rock only produces glassy materials?  That objection seems pretty damaging to the overall UM thesis, if you ask me.

As I keep reading the Science article I notice something.  Sessions says these scientists “observed an astonishing amount of heat generated” during the Bolivian quake, but they didn’t actually do heat flow measurements, like they did for the Tohoku quake.  They took various estimates of the parameters governing the quake, and fed that information into a model, so it’s not really an “observation.”

Also,  how did Sessions get that in one “fault area of the Bolivian quake… the melted thickness was only 3.7 mm”?  The scientists didn’t say that.  They said that IF the thickness of the melted layer were only 3.7 mm, they calculated the local temperature rise to be about 52,000 °C along the fault.  With that much heat energy released, they calculated a maximum melt thickness of 31 cm.  Math.  It’s important in science.

In any case, what if the heat generation estimate for the Bolivian quake was actually pretty good?  Would it still be the bombshell discovery Sessions wants it to be?  I mean, is a maximum of 31 cm of molten rock along a fault really all that much, and do the scientists who wrote the article think the kind of frictional melting that might have happened during the Bolivian quake is likely to be common, or was this an unusual event?  Here are some snippets from the article that Sessions didn’t get around to quoting.

Although this amount of heat does not significantly con-tribute to the global heat flow, it can influence the local thermal budget in subduction zones…. (p. 840)

The thickness… cannot be determined directly from seismological data, but weakening as a result of melting is likely to localize deformation on a thin zone, as is seen in pseudo-tachylytes.  The small upper bound for the fault-normal displacement also suggests a fairly simple dislocation source, and a large complex volumetric source is probably ruled out. Thus, [a thickness of the melted layer] as small as a few millimeters is plausible…. (p. 841)

It is unclear whether the Bolivian earthquake is fundamentally different from other deep-focus earthquakes…. No evidence for slow rupture speed has been found for other deep-focus earthquakes, with the possible exception of the equally large 1970 Colombia earthquake (Mw = 8.2)…. Because of these uncertainties, it is unclear whether melting plays a major role in other deep-focus earthquakes. Deep-focus earthquakes may be different from event to event….  (p. 841)

So their answer is basically that the heat generated in the ENORMOUS (magnitude 8.3) Bolivian earthquake really isn’t that much heat in the grand scheme of things, and the magma generated was probably only a few mm thick.  And even though there are lots of questions still unanswered on this topic, there are some reasons to believe the amount of frictional heat generated by the Bolivian quake was somewhat exceptional.

I don’t think this astonishing string of misreadings and oversights was intentional, but I do think it provides a good illustration of Dean Sessions’ mindset.  If he runs across information that contradicts his ideas, he simply can’t process it unless he has a ready reply.  Also, any scientific observation or conclusion that points even vaguely in the direction he wants is immediately co-opted to argue for conclusions that go WAY beyond anything the scientists demonstrated, or even conjectured.  If Sessions does acknowledge that he’s doing this, it is taken as proof of the scientists’ confusion and general stupidity, and of Dean Sessions’ great genius.

 

 

 

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Responses

  1. Time to close your blog now , Barry…..it’s all over….we’ve entered the New Trumpocene….
    http://principia-scientific.org/is-no-greenhouse-effect-possible-from-the-way-that-ipcc-define-it/#comment-11469

  2. And where women will be assaulted and anyone not white and male evicted and where all education and healthcare will be done on a maximising profit basis, if you can’t pay, its your fault.

    Yet somehow I don’t see anyone giving up on all those things.

    Besides if you really thought you had to give up, you’d just walk into the HoR and shoot the fuck out of the senators or loan a wad to go to Maralago and execute trump and his “cabinet of curiosities”.

    Sure, you’ll be executed for mass murder, but so what? You gave up, why bother with consequences, eh?

    But you won’t. Because you HAVEN’T given up on everything, and consequences and the actions you personally take still matter to you, and those are acts you do not want to take or live with.


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