26 April 2018

Subduction Events, Related Volcanoes – and Nephi’s Smoking Gun

           
In 1973 Hugh Nibley gave a lecture at the University of Arizona. We tried to get him to autograph our copy of his book, “Since Cumorah,” (Nibley, 1967), but he initially refused. “There are so many better examples now available, some discovered even as this book was being printed, that I’m embarrassed to sign this poor thing.” Eventually he signed it, however, and the book is still treasured by our family.
            In fact, while “Since Cumorah” was going through the publishing process and for years afterward, hundreds of new geographic and scientific discoveries have been made (and are still being made) supporting the veracity of historical and geographical details in the Book of Mormon. All of these appeared more than a century after the Book of Mormon was first released and were, of course, unknown to anyone in Joseph Smith’s time, let alone a poorly-educated young man living on the edge of a rough frontier.
            For example, one item that did not make it into “Since Cumorah” was the surprising similarity of details in 3 Nephi 8 to the events surrounding the 1980 eruption of Mount St Helens, which took place 13 years after “Since Cumorah” was first published. To a professional volcanologist, this chapter accurately describes a cataclysmic volcano-tectonic event on a major subduction zone. Yet volcanoes, earthquakes, subsidence, and allocthons are geological phenomena that don’t exist within 3,000 kilometers of western New York State, nor were they known to any Americans in 1828.
Joseph Smith grew up in Vermont and New York State. He received only three years of formal education in his entire lifetime. Western New York is covered with glacial moraines – huge gravel and boulder piles shoved down from their origins in Canada by the glaciers that retreated with the Younger Dryas epoch about 11,700 years ago at the end of the last Ice Age. Cumorah, the hill where Joseph found the golden plates that he translated as the Book of Mormon, is one of these glacial moraines. Joseph Smith had never seen a volcano nor felt an earthquake in his short life. A primitive form of the field of volcanology existed at the time, mainly in Italy around Vesuvius, Etna, and Stromboli volcanoes, but Pompeii and Herculaneum had not yet been seriously excavated. Tectonics as a scientific field would not develop until more than a century later.
            Back to Mount St. Helens: Its 1980 eruption was classified as a VEI 5 event – that stands for “Volcano Explosivity Index Level 5.” This VEI scale (Newhall and Self, 1982) is approximately logarithmic: a VEI 4 is about 10 times smaller than a VEI 5 event, and a VEI 6 is about 10 times greater than MSH 1980. Third Nephi, chapter 8, describes a geological event that would rank somewhere between a VEI 6 and a VEI 7. In 3 Nephi 8 we encounter expressions such as "...there were exceedingly sharp lightnings...", "...the city of Moroni did sink into the depths of the sea...", "...the whole face of the land was changed...", "...there was darkness upon the face of the land...", and "...the inhabitants thereof who had not fallen could feel the vapor of darkness..." describing the disaster that engulfed the Nephites nearly 2,000 years ago.       
Huge, hot pyroclastic density currents and tephra typically burn and bury all living things within their reach during these events, and completely reshape the face of the land. Magnitude 8+ earthquakes sink cities and everything else – there is a drowned forest in Puget Sound that was sunk by the January 1700 AD subduction megathrust earthquake (Atwater and others, 2005; 2015). Earthquakes this violent commonly redistribute whole sections of mountains to cover and fill valleys, sometimes even causing flanks of mountains to slide so fast that they fly through the air before they hit; these are called allocthons by geologists; and these monster events make smooth places very, very rough.
For “vapor of darkness” substitute “volcanic ash” and everything falls precisely into place. This kind of ash suffocated many of the people who died during the eruption of Mount St Helens on May 18, 1980; and the city of Yakima, Washington, was essentially shut down hours later as a meter-thick blanket of ash fell on the town. Contemporary descriptions tell us that day turned to night and the street lights came on around noon (Waitt, 2015). Please keep in mind that the May 18, 1980 eruption of Mount St Helens was relatively small when compared to ash and tephra falls now well documented in Central America.
Central America, of course, is an integral part of the Pacific Ring of Fire, so called because of the string of volcanoes that all lie just inland from the Pacific Ocean margins. The Ring of Fire includes hundreds of volcanoes, some of them HUGE, including supervolcanoes like Cerro Hudson in southern Chile, Masaya in Nicaragua, Katmai and Veniaminof, in the Aleutians, Sheveluch and the Mutnovski-Gorely complex in Kamchatka, Aira in Japan, and Taupo in New Zealand. We can't leave out Mount Pinatubo in the Philippines, whose 1992 eruption lowered the worldwide temperature by two degrees Celsius, and we must include the long arc of volcanoes in Indonesia fronting the Indian Oceanic plate, including the monster Toba. The phenomenal eruption of the Toba supervolcano around 72,000 years ago may have reduced the proto-human population on Earth to less than 10,000 individuals, according to genetic studies (Gibbons, 1993; Ambrose, 1998).
            All these volcanoes (except the Indonesian archipelago volcanoes like Toba) lie just inland of the Pacific Ocean margins because they lie just above their sources: the down-going Pacific Ocean seafloor that is being over-ridden by continental margins all around it. Linking each over-riding continental plate with its subducting oceanic plate are huge subduction faults. These are the sources of the largest earthquakes in Earth's recorded history, including the magnitude 9.5 Valdivia earthquake of 1960 in Chile (which caused a tsunami that destroyed downtown Hilo, Hawai'i, about 8 hours later). Other subduction earthquakes include the magnitude 8.7 to 9.2 Cascadia event of 1700, which sank an entire forest in Puget Sound, and then created the "Orphan Tsunami" that destroyed villages on the Japanese east coast (Atwater and others, 2015). The magnitude 8.6 Aceh subduction earthquake of 2004 triggered a tsunami that killed at least 250,000 people along the Indian Ocean margins. The magnitude 9.0 Tohoku Earthquake of 2011 triggered the meltdown of the Fukushima-Di-Ichi nuclear plant and devastated the northeastern Japanese coast yet again.          
            During the colonization of Central and South America by Spain, a number of regional Central American capitals (including Santiago de Guatemala, and Managua, Nicaragua) were repeatedly buried and/or pulverized. In each case, the city had to be entirely rebuilt, often in a different location.  To say that earthquakes and related volcanic tephra-falls have changed the face of the land in Central America would be an understatement.
            Since the 1963 eruption that created the island of Surtsey, Iceland, and especially since the 1980 eruption of Mount St Helens, volcanologists have known that lightning storms are closely associated with Plinian eruptions (named for Pliny the Elder, killed by the eruption of Vesuvius in 79 AD). This is because of the prodigious electric charge dragged aloft along with the vast amounts of volcanic ash that are blasted up to the stratosphere. Those electric charges accumulate until voltage differences are so great that they must discharge back to the earth via lightning.
            But what caused the "vapor of darkness" described in 3 Nephi 19 and 20? This was almost certainly a smothering blanket of volcanic ash. As attention-garnering as it was, Mount St. Helens 1980 was a relatively small eruption (VEI level 5). Yet this event still lofted about 3 cubic kilometers of material and left nearly a meter-thick blanket of ash on Yakima, Washington, 240 kilometers to the east, within a few hours of its eruption (Waitt, 2015). Can ash put out fires? Yes – ask any forest fire fighter (one of us worked his way through college fighting forest fires each summer) or ask anyone who learned how to shovel dirt and ashes onto a campfire to smother it.
            So, what caused all this destruction? To get a handle on a “smoking gun” responsible for 3 Nephi 8, we must examine the largest volcanic eruptions in Central America (Sigurdsson et al., 2000; Jordan, 2003; Kutterolf, et al. 2008; Grover, 2014). One sneaky but efficient way to do this is to accumulate information on tephra, the fragmental (pea-to-cantaloupe-size) material blown out by a volcanic eruption. More to the point, we want to know how far the tephra reached (we are not really interested in ash here, because ash can travel all around the earth). The greater the distance that the tephra falls reached, the larger was the eruption. Two events stand out:
  • Masaya volcano, Nicaragua, about 2,100 +/- 100 years ago. It deposited tephra as far as 170 km distant.
  • Chiletepe volcano, Nicaragua, erupted about 1,900 +/- 100 years ago and dropped tephra as far as 570 km distant.
            Note that these dates are very approximate (see Kutterolf, et al., 2008). 
            The Masaya eruption lofted approximately 8 cubic kilometers of ash and tephra, nearly three times more than Mount St Helens in 1980. Both Chiletepe and Masaya lie east of the subduction zone where the Cocos Plate is being over-ridden by the Caribbean Plate at a rate of nearly 7 cm/year.
            This rate of crustal movement is important, because it is nearly three times faster than the Cascadia subduction rate in the Pacific Northwest of the US. This faster subduction rate means that there are proportionally larger and more frequent volcanic eruptions in Nicaragua than in the Washington and Oregon Cascades. Central America is basically a gargantuan pile of volcanic lava, tephra, and ash covered with recent soils and vegetation. In that sense, 3 Nephi 8 doesn’t record such a remarkable event, at least not by local standards – except for the timing of it.
            In other words, the Book of Mormon is fully conformable with the geologic record of Central America.
            This subduction-earthquake-volcano cataclysm is just one example among many where modern science seems to be converging with events and geographical details recounted in the Book of Mormon.  Other examples include linguistics (for instance chiasmus, Egyptian names, and other Semitic cognates seen in the Bible (see Welsh, 1969; 1981), and the remarkable correlations of the first 17 chapters of the Book of Mormon with the still-accumulating details of the Frankincense Trail (see Hilton and Hilton, 1976; Givens, 2002). The stories recorded in the Book of Mormon by prophets over the 1,021 years of its internal history are remarkably consistent with geologic, geographical, and historical evidence now known.  The Uto-Aztecan language group in the Western Hemisphere is loaded with both cognates and fossil linguistic structures only found in Semitic languages of the Arabian Peninsula (Stubbs, 2016). 
          None of this information, however, was available in Joseph Smith’s lifetime. None of it "proves” the veracity of the Book of Mormon – but it sure hints at that direction pretty strongly.  
             

           That name Masaya is a coincidence, but it still took my breath away. 


13 December 2017

Is Water Wet?

In the response below I had to throttle back my Inner Scientist from wanting to strangle certain abusers of social media. Facts are NOT the same as Alternative Facts. Internet Foo-Foo is NOT truth. Much of it represents all the bad consequences of the 1st Amendment to the American Constitution - without any redeeming good.

Q: So on social media there’s been a huge debate on whether water is wet or not. I believe water is not either wet or dry. So is water wet?  - Kacie M

A: This is akin to Medieval arguments about how many angels could dance on the head of a pin. In other words, it's a pointless issue. Water is water. Wet means something has water on or in it in all versions of the English language that I am familiar with. I did a cursory look and did not see a "huge debate" on social media about water being wet or not. 

Social media should NEVER be considered a source of meaningful information, as there is no vetting, no peer review of the content you see there. People make up "Alternative Facts" and post them to social media, and if it's done with flashy visuals, some weak-minded and poorly educated people might take this stuff as fact. Don't YOU fall into that old make-up-a-fact trap. That's what humanity fought its way out of the Middle Ages to get away from. Your smart phone doesn't work because of some made-up fact about electricity.

16 January 2017

Climate Change - Is It Real?

Repeatedly I have had questions about climate change addressed to me, both electronically in USGS Ask-A-Geologist queries, and verbally from acquaintances  There are a lot of things floating around in the news media about climate change. A lot of this is correct, some of it is foo-foo, and far too much of it is deliberate obfuscation by people who have a self-serving financial agenda. 

Sadly, there are scientists who sell their souls to corporations (whether Big Carbon, Big Pharma, or Big Tobacco), but we will not go there...


Q: Is climate change real, is is this some liberal Mother Earth Tree Hugger thing going on?


A: A short summary of what's going on:

THE KNOWNS:
1. Virtually all climate specialists not paid by Big Oil agree that the Greenhouse Effect is real. In fact, it was first reported in the scientific literature by Joseph Fourier (of Fourier transform fame) in 1824. It's been tested and proven repeatedly ever since.

2. There is a lot of yearly and decadal variability in climate data. Anyone can cherry-pick the weather data to prove any point they want to - including waving a snow-ball in a Senate hearing - but that's not science. If someone is trying to convince you that climate change is not happening, ask yourself: who's paying this guy?

3. CO2 in the Earth's atmosphere has gone from 315 ppm in 1958 to over 400 ppm today (Mauna Loa observatory). Virtually all scientists with integrity accept that most if not all of this change is due to human activity. The reason? The change has been accelerating (second derivative is positive) since about 1850, when the industrial revolution really got underway. By second derivative being positive, I mean that it is ramping up faster and faster as time progresses. This is the well-known "hockey stick" graph made famous by Al Gore. 

4. Is the increase in CO2 human-caused? If we look at the carbon isotopes in this increased atmospheric CO2, we can show that it is definitely caused by fossil fuel burning. Carbon-14 is a radioactive isotope with a half-life of 5,730 years. There is a certain amount in the atmosphere and living plants from cosmic rays transforming nitrogen in the upper atmosphere - this is well-calibrated by many studies. With a half-life this short, if something bearing carbon is buried and put out of reach of the atmosphere, the carbon-14 drops below measurable levels by 50,000 years. Fossil fuels thus have NO carbon-14 in them. Burned, these fossil carbon sources contribute only carbon-12 and carbon-13 to the atmosphere. It's not hard to calculate how much fossil carbon has been burned: about 300 billion tons since 1800 AD. It's also not hard to measure the levels of carbon-14, the radioactive isotope, in the atmosphere over the past two centuries: it's sequestered in tree-rings and other places where it can be measured, year by year. Human involvement in the growth of CO2 in the atmosphere is proven by the steady drop of carbon-14 levels in the atmosphere since 1800.  

5. The last time the atmospheric CO2 reached this 400 ppm level, according to the geologic record, was during the Pliocene (5.3 to 1.8 million years ago). At that time, about half of Florida was underwater (including the places where ~80% of Florida's population now lives). I've pulled Pliocene marine fossils (sharks' teeth and echinoderms) out of land deposits in central Florida with my own hands; they are on my bookshelf.

6. There is a latency of CO2 after it gets into the atmosphere, and some scientists calculate this to be about 30 years. Translation: it tends to stay there. The oil you burn today will really be impacting your kids 30 years later. 

7. A gallon of gasoline, which weighs 3 kg, will produce about 10 kg of CO2. The extra mass comes from the oxygen you might want to breathe instead. That gallon translates to 50 kilometers traveled in my car. And that's not counting the CO2 generated to extract and refine the gasoline. The Energy Returned on Energy Invested for Athabascan tar sands is between 4 and 7. Translation: a rather huge amount of energy is used up just getting the bitumen into the form of gasoline. 

8. Nearly 5 billion impoverished people on Earth want to have a high-protein lifestyle like their grandparents could not have even dreamed of. This means vastly-increased herds of vegetation-eating, meat-producing animals. The amount of methane a cow produces is truly breath-taking (pun intended): up to 500 liters of methane a DAY. That's more than a 5-drawer file cabinet. Methane is 37 times more potent than CO2 as a Greenhouse Gas for capturing solar heat. That pushes it up beyond the volume of my office in CO2 equivalent - in one day. One normal, flatulent cow.

9. Increased temperatures mean more glacier calving, and more melting of Arctic, Antarctic, and Greenland ice caps, which are collapsing at truly stunning rates - and the collapse accelerating. Less ice on the ground and on the polar oceans means that the darker - light-and-heat-absorbing - under-layers will be exposed, trapping yet more solar heat and making the inevitable change non-linear. Translation: these changes are accelerating with time. 

10. Nine of the ten hottest years in now-centuries-old records have happened in the 21st Century. 2016 was the hottest year, globally, ever.


It's not hard to draw some conclusions from all this:

1. Do NOT buy beach-front property, Anywhere.

2. Move to the Pacific Northwest, or the Canadian prairie provinces. They will be among the very few winners of climate change. 



THE UNKNOWNS:
There are still several unresolved questions:

1. How FAST?
How quickly will the global climate change consequences befall us? The current speed of change has never happened before, as far as geologists can tell, in Earth's history. Ever. Predicting our future depends on climate modeling, and these models are fraught with assumptions and disagreements. However, they are beginning to coalesce, and they are now in general agreement. 

2. How BAD?
Likely consequences include (but these cannot be easily quantified):

  • Sealevel rise... and because of tectonic settling this will be worse on the east coast of the U.S. This means more, far-reaching devastation from storms like Katrina and Sandy are in our future.
  • We can expect bigger and more devastating hurricanes and tornadoes. If seawater rises and hurricanes grow in average size, then the storm surges they drag with them will reach deeper and deeper into the continental interiors. About 80% of humanity now lives within 100 km of a seashore.
  • Greater and more terrible droughts and wildfires can be expected. Because of well-intended but ultimately catastrophic wildfire suppression policies over the past century, these fires will become truly terrible in the continental U.S., Russia, and Brazil.
  • A consequence of droughts and wildfires: massive disruption in the world's food supplies.
  • We are already seeing the sixth mass extinction of animal life - and explosions of other destructive types of life (e.g., jellyfish, toxic algae). The current mass extinction of wildlife (habitat destruction and over-hunting) is comparable to what the Chicxulub asteroid did 66 millions years ago.
  • We are already seeing acidification of the oceans, with consequent dissolution and destruction of coral reefs, a major host of biodiversity - and the world's protein supply. The Great Barrier Reef of Australia is catastrophically collapsing as I write this.

3. Is it already beyond our control?
The question arises: are we already at the "tipping point"? The effect of climate warming on gas hydrates (methane clathrates) that lie beneath the continental shelves is a HUGE unknown. Most estimates (from seismic reflection data) suggest that these clathrates are many orders of magnitude greater than all other known hydrocarbon reserves (coal. oil, gas) on Earth combined. Gas hydrates are methane trapped in water ice below about 300 meters of seawater. This is the depth where pressure and cold ocean-floor temperatures currently trap them - where they remain stable. These methane hydrates have accumulated over millions of years from dying sea-life that drops to the ocean floor (some may derive from oil and gas deposits below the sea-floor sediments). A single cubic meter of these "gelids" can produce up to 180 cubic meters of methane - the internet is replete with photos of "ice" that is burning. A crucial unknown: will attempts to extract this stuff "open the doors" to a catastrophic release of vast quantities of methane into the atmosphere? 

The gas hydrates/methane clathrates issue leads to inevitable questions about non-linearity in climate forcing - and tipping-points. In other words, can things get out of control? Is it already too late - will we see a runaway temperature rise? Will we see inundation of most of the world's great cities (a real Waterworld)?


The geologic record suggests it may very well be too late - it's happened before for natural reasons - but the geologic record also shows that the Pliocene warm period came on far more slowly than what we are seeing in our modern world climate: it took hundreds of thousands of years to raise CO2 levels then - something that humanity has accomplished in just the past half century.

We are already in unknown territory, and precise predictions are probably not going to be correct.  
~~~~~

08 August 2016

Scientism - Its Fatal Flaw

Well, *I* believe in SCIENCE! 

Heard that before? It's certainly nothing new - it goes back to at least Voltaire.

Scientism is an expression in use for most of the 20th Century, and is often used to refer to science applied in excess - or applied unreasonably. The term scientism can generally apply in either of two ways:
  1. To indicate the improper usage of science or of scientific claims,  
  2. To refer to a belief that methods of natural science form the only proper elements in any inquiry.
In a broader sense, scientism is also used to describe the invocation of science as a focus of worship, generally by people who would describe themselves as atheists. It's sort of like Methodism, or Daoism, or... you can fill in the blanks here.

Two recent articles, "Lies, Damned Lies, and Medical Science", and "Trouble at the Lab" draw some obvious and frightening conclusions about this approach or life view.

John Ioannidis, a physician and mathematician, published two seminal articles in 2005. They are among the most-cited papers in all of modern science - and they are incredibly embarrasing to scientists. In the first paper, Ioannidis convincingly showed why 80 percent of non-randomized scientific studies turn out to be wrong. Fully 25 percent of supposedly gold-standard (and thus far more expensive) clinical trials gave incorrect results. It is from studies like this that the medical doctors that you and I seek help from base their diagnoses and treatment protocols. Our lives depend on these being correct. These incorrect results include recommendations to use hormone-replacement therapy in post-menopausal women, that mammograms and PSA tests are critical for extending lives, that anti-depressants such as Prozac, Zoloft, and Paxil can help depression, that doing puzzles will ward off Alzheimers Disease, and that drinking lots of water during intense exercise is helpful.

The problem? Not one of these turns out to be true. THOUSANDS of stories in magazine articles have been written based on these published studies. The number of studies that contradict other studies of the same thing are so high that The Week magazine actually has a section called "Health Scare of the Week".

Many physicians, on their own, have discovered that just taking a patient off of every drug can improve their health immediately. 

The truly glaring problem: the large majority of these studies cannot be replicated. This means that other groups cannot repeat the same experiments and get the same results. Amgen, an American drug company, tried to replicate 53 landmark studies in basic research on cancer. They were able to reproduce the results on just 11 percent of the studies. In a separate study done by Bayer, the German pharmaceutical company, only 25% of published results could be reproduced. These analyses aren't being published by disgruntled scientists, but by editors in the premier of all science journals: Nature. Dr. Ioannidis says that between a third to a half of  medical research results has been shown to be untrustworthy. He suggests that physicians, when faced with all this potentially lethal error and confusion... simply ignore them all!


Ioannidis' second paper explains why these flawed studies happen and get published in peer-reviewed journals. Without belaboring the details (you can read them yourself), it comes down to many things - but things that compound themselves:
  • The "publish or perish" ethos for young scientists to get tenure or grants
  • Ignorance of what constitutes statistical significance among most scientists
  • Ego
  • Fear of reprisals by peers or superiors
  • The tendency of scientific journals to publish almost exclusively "new" and "exciting" discoveries
  • Bias in research study design, bias in analysis, self-serving interpretation
  • Fraud.
This latter issue is interesting, and when identified firmly it is supposed to lead to retractions of published articles. However, a University of Edinburgh study of 21 confidential surveys of scientists worldwide found that only 2 percent of them admitted to falsifying or fabricating data - but 28 percent said they knew of colleagues who engaged in these practices! If that difference hints to you at a broader problem, then give yourself three stars. 

The problem with Scientism is that it falls for the oldest trick in the book: it worships at the feet of the Golden Calf. One of several modern versions of the Golden Calf is Science. But like all man-made things, their faith is based on something that is fatally flawed. It is very, very human.

Are we advocating that people not trust science? Absolutely not - just don't bet your life on it, and certainly don't pour your faith and belief into it! Science is still far better and more honest than the The Talking Heads and Corporate Paid Pundits on talk radio or "fair and unbiased" news channels. 
~~~~~

24 June 2014

Hot Magnetic Oxygen Water World

There is another version of the Anthropic Principle, one that applies only to the planet Earth. We may be more alone, or unique, in this universe than the Drake Equation - the calculation of the possibility of other life out there in the universe - may have led us to believe.

The deepest hole ever drilled into the Earth's crust reached down to about 7.6 miles (12 km) below the Kola peninsula of northern Russia. The technology available to humankind cannot get below that depth (and that depth took 24 years of drilling and billions of Rubles to achieve). The rocks are so hot and plastic with overlying rock pressure at those depths that the hole closes in on the drill bit - and partially fills the shaft back in from the sides as the bit is drawn back to the surface to be replaced. So... the maximum depth achieved by humanity's best effort is less than 1/10,000 the Earth's diameter, or the distance of a short commute on a Monday morning. We actually know more about galaxies, comets, and the moons of Jupiter and Saturn than we do about what lies below our feet on our own planet. No matter how you look at it, we cannot really touch virtually all of the world beneath our feet.

In other words, everything we think we know about the interior of the Earth is obtained by very indirect means, and a lot of this is from mathematical modeling.

To see below the depth of the Kola well, we must rely in electrical geophysical methods like magnetotellurics (which is one of the things that I "do" as a geophysicist; it can detect resistivity layering down to perhaps 50 km or so), and on earthquake seismology. For nearly a century seismologists have traced the powerful vibration signals from very large earthquakes as these signals propagate and refract through the Earth. By comparing the time of arrivals elsewhere around the planet - and whether just P-waves, or P-waves and S-waves together make it - they can discern contrasts in density and other physical parameters as these change with depth. P-waves (or primary waves) are pulses of energy, momentarily compressing the material they pass through. It's the blast wave from an explosion expanding outward. S-waves (or secondary waves) are shear waves, oscillating material back and forth, sideways, as they pass through the material. Think of how you would move your hands forward and backward to tear a piece of paper. A key feature of S-waves is that they cannot propagate through a liquid. Think of trying to use your hands to tear water. By the 1920's seismologists had used the initial earthquake seismic information and some density calculations to conclude that there is a solid iron core to the Earth, surrounded by an outer liquid iron part of the core. The outer liquid core is overlain by a hot and plastic Mantle, and finally by a relatively thin crust serving as a very thin solid shell above them both. All living things live on or just beneath the top of that crust.

The methodical genius who first figured all this out was a quiet Danish lady named Inge Lehmann, who died in 1993 at 104 years of age.

Seismology and magnetotellurics show us the layering in the Earth with depth. Indirectly we also know that the center of the earth is very hot. After all, there are volcanoes and fumaroles, and the deeper you mine in places like South Africa the hotter it gets. Nearly everywhere scientists have measured temperature in wells, a thermal gradient exists: deeper means hotter. But we also know there is a lot of heat below us for several other reasons, including plate tectonics. SOMETHING has to be powering whole continents to be able to wander around. And then there's the magnetic field of the earth.

What distinguishes Earth from Mars and the Moon? A magnetic field, an atmosphere, liquid water - and life. The last requires the first three in our limited observations so far. Without a magnetic field to deflect it, Solar radiation would  sterilize the Earth and disrupt any attempt for life to gain a foothold. Solar radiation would also strip away any atmosphere, which is apparently why Mars doesn't have much atmosphere left to speak of. Mar's atmosphere is only a few percent of the density of our own atmosphere - though there is evidence of much more at one time in the distant past.

What distinguishes Venus from the Earth? Venus has an atmosphere, but it has fallen under a runaway Greenhouse Effect - too hot for water and in fact so hot that raw sulfur is a liquid on its surface. The Earth lies in what is sometimes called the "Goldilocks Zone" where it's not too hot and not too cold, between roasting Venus and frigid Mars. Water on Earth not only exists, but can exist in all three states (solid, liquid, and gaseous). This is not so for Mars or Venus, neither of which has a magnetic field, nor plate tectonics, nor significant water.

It has been apparent for quite awhile that the Earth's magnetic field is the reason why life exists on our planet. A magnetic field, however, requires some sort of dynamo to create and sustain it. How to power this? Well, if there are enough radioactive elements - or sufficient heat from the collapse of the proto-planetary disk to form our planet - well then maybe there is enough energy to drive a dynamo. However, this requires a lot of assumptions that scientists cannot test - they can't drill deep enough.

There is another problem: hot things tend to cool when surrounded by colder things... like interplanetary space. A magnetic field driven by an internal dynamo cannot last forever.

Hot things cool in two ways: by conduction and/or by convection. Conduction is like the metal pot you cook your cream of wheat in. Heat transfers from a hot source beneath to a cooler part above without any motion of particles involved. With convection, however - the bubbling cream of wheat - the heat is transferred by particles moving in three-dimensional loops called hydrothermal cells. You see them as bubbles driven by steam in the sauce pan. A hotter particle of the wheat from the bottom, in contact with the metal pan, rises because it is hotter (and thus less dense) than the particles above it, thus transferring heat from the bottom to the top of the cream of wheat. If the stuff cannot convect - if it's not liquid enough - then it will get hotter and hotter until it burns. It not only tastes terrible, but the sauce pan is a bear to clean up afterwards. In the same way, the solid iron core can only conduct heat out; like the metal sauce pan it cannot convect heat. However, the liquid iron outer core and the hot and plastic mantle above it can convect heat - and these convection cells of highly conductive material must be the source of the magnetic dynamo. The convection cells in the mantle are also what's driving whole continents around across the face of the Earth.

Remnant magnetization in rocks 3.5 billion years old, however, proves that the Earth's magnetic dynamo has existed for at least that long. The oldest known life is found in stromatolites - clumps of cyanobacteria - just about that old. This is not a coincidence. If there was no protective magnetic field, the stromatolites and then algae (and Earth's atmosphere) would not have survived Solar winds and radiation. But 3.5 billion years is a long time for something to stay hot enough to drive a magnetic-field-producing dynamo. Older computer models based on relatively low thermal conduction assumptions for iron seemed to suggest that it would take awhile for the solid iron core to give up its heat. This could conceivably sustain a dynamo lasting that long.  According to these older models, the heat from the core would take billions of years to conduct out to the outer liquid core and Mantle where a different form of heat transfer - the much faster convection - takes place.

In the last several years, however, scientists have been forced to re-evaluate what they think they know about the center of the earth. Several years ago, another piece of information became available from some Japanese extreme-high-pressure experiments. Iron at pressures and temperatures we calculate must exist in the center of the Earth has a far higher thermal conductivity than anyone had thought could be possible. According to milecular orbital theory, if you smash material together hard enough, it frees up electrons and changes its conductivity. This means that the Earth's heat-driven dynamo should have burned out billions of years ago. In other words, the Earth's magnetic field would have then died, and the atmosphere and any nascent life would have all disappeared before most of the geologic record could even take place. Think of dead Mars.

Speaking of geology, fluid and gas inclusions in ancient rocks tell us that around 2.5 billion years ago the Earth's primordial atmosphere of CO2 and nitrogen transitioned to an oxygen-nitrogen atmosphere. The world as we presently understand it began then. In part we can blame this on the stromatolites and photosynthesizing plant life that was expanding at that time.

In the 1970's a few scientists offered what seemed like a ridiculous idea: the Moon formed well after the Earth formed. It formed in its current size and shape when a large Mars-sized planetoid crashed into the proto-Earth and splattered material into space around the Earth. That material blasted into multiple orbits then coalesced to form the Moon, leaving a very different - and very hot - planet Earth behind. Computer models show that this is easily feasible. If so, then the Earth would have glowed like a small star from the massive infusion of heat from all the kinetic and potential energy of the collision. This idea is now taken seriously for several reasons, but mainly because the rocks on the Moon are sooooo much like the rocks on the Earth, and sooooo different from rocks on Vesta, Ceres, Mars, and Venus. We can discern these by optical spectroscopy, coupled with sampling meteors that the spectroscopy says must come from those places.

Could that ancient impact hold the answer for why we have such a long-lasting magnetic field around our planet? That seems to be the best explanation at this time. If so, then life exists on this planet because of some pretty amazing circumstances: 
  • it exists in a narrow Goldilocks Zone, 
  • it was given a huge heat boost by a collision from a large planetoid, and 
  • its crust was given a lot of water from impacting comets that allowed it to be less solid, more flexible, and have an ocean of liquid water. 
  • Photosynthesis then started early and gave this planet an oxygen-nitrogen atmosphere, and finally
  • The Earth's magnetic field lasted a very, very long time.


Those are a lot of things that had to come together at just the right time for life to form and evolve here.

There are so many coincidences - like the Anthropic Principle that allows molecules - and thus life - to exist. It seems remarkably like our Earth has its own local version of the Anthropic Principle: just the right features and additions at just the right times to allow life to form and evolve over an extended period of time.

Bruce Buffett, a geophysicist at Berkeley puts it this way: "The more you look at this and think about it, the more you think it can't be a coincidence. The thought that these things might all be connected is kind of wondrous." (Discover, July/August 2014, p. 41)


With all the exoplanets being found in solar systems nearby in the Milky Way Galaxy, what is the likelihood that one of them could have all these coincidences? Since Galileo, humanity has been humbled to know that it isn't the center of the universe. 

However, it appears that we certainly are unique.
~~~~~

31 December 2013

Masaya

Anyone who has read 3 Nephi 8, especially if they are aware of some of the details of Mount St Helens' 1980 eruption, have pondered expressions such as "...there were exceedingly sharp lightnings...", "...the city of Moroni did sink into the depths of the sea...", "...the whole face of the land was changed...", "...there was darkness upon the face of the land...", and "...the inhabitants thereof who had not fallen could feel the vapor of darkness..." that engulfed the Nephites nearly 2,100 years ago.

Central America, of course, is an integral part of the Pacific Ring of Fire, so-called because of the string of volcanoes that all lie just inland from the Pacific Ocean margins. The Ring includes hundreds of volcanoes, some of them HUGE, like Cerro Hudson in southern Chile, Masaya in Nicaragua, Shasta in California, Mount Rainier in Washington, Mount Edgecumbe near Sitka, Alaska, and Katmai and Veniaminof, the monster volcanoes of the Aleutians. Farther east, on the other side of the Pacific Ocean, the Ring of Fire includes Bezymiani, Sheveluch, and Mutnovski-Gorely in Kamchatka, and Alaid and others in the Kuriles. The Ring includes Usu, Fuji, and Sakura-Jima, the best-known volcanoes in Japan. We can't leave out Mount Pinatubo in the Philippines, whose 1992 eruption lowered the world wide temperature by two degrees centigrade, and we must include the long arc of volcanoes in Indonesia, including the monster Toba. The phenomenal eruption of the Toba supervolcano around 72,000 years ago may have reduced the proto-human population on Earth to less than 10,000 individuals according to genetic studies.

All these volcanoes (except for Indonesia) lie just inland of the Pacific Ocean margins because they lie just above their sources: the down-going Pacific Ocean seafloor that is being over-ridden by continental margins all around it. Linking the over-riding continental plates with their subducted oceanic plate are huge subduction faults. These are the sources of the largest earthquakes in Earth's recorded history, including the magnitude 9.5 Valdivia earthquake of 1960 in Chile (whose tsunami destroyed downtown Hilo, Hawai'i, about 8 hours later). Other subduction earthquakes include the magnitude 8.7 to 9.2 Cascadia event of 1700, which sank an entire forest in Puget Sound, and whose "Orphan Tsunami" destroyed villages on the Japanese east coast. The magnitude 9.0 Tohoku Earthquake of 2010 triggered the meltdown of the Fukushima-Di-Ichi nuclear plant and devastated the northeastern Japanese coast. The huge magnitude 8.6 Aceh subduction earthquake of 2004 created a tsunami that killed at least 250,000 people along the Indian Ocean margins.

During the Spanish era, a number of regional Central American capitals such as Santiago de Guatemala and Nicaragua, Honduras, were repeatedly destroyed and rebuilt. To say that earthquakes and related volcanic tephra-falls changed the face of the land in Central America would be an understatement.

Since the 1963 eruption that created the island of Surtsey, Iceland, and the 1980 eruption of Mount St Helens, volcanologists have known that lightning storms are closely associated with Plinian eruptions. This is because of the vast electric charge dragged aloft along with the prodigious amounts of volcanic ash that are blasted up to the stratosphere.

But what caused the "vapor of darkness" described by Nephi? This was almost certainly a smothering blanket of volcanic ash. Mount St Helens, 1980, was a relatively small (VEI 5) eruption. This event lofted about 3 cubic kilometers of material, and left nearly a meter-thick blanket of ash in Yakima, Washington, 244 kilometers to the east, within a few hours of its eruption.

To get a handle on a smoking gun for 3Ne:8, we must examine the largest volcanic eruptions in Central America. One way to do this is to accumulate information on tephra falls that reached out great distances - the larger the reach, the greater the eruption. Two events stand out:

  • Masaya volcano, Nicaragua, about 2,100 years ago, left tephra as far as 170 km distant.
  • Chiletepe volcano, Nicaragua, about 1,900 years ago, left tephra as far as 570 km distant.
Note that these dates are somewhat approximate (they come from Kutterolf et al, 2008, Geochemistry, Geophysics, Geosystems). The Masaya eruption lofted approximately 8 cubic kilometers of ash and tephra, nearly three times more than Mount St Helens. Interestingly, ancient human footprints have been found at Acahualinca - these are ~2,100-year-old fossils discovered along the shores of Lake Managua, Nicaragua, frozen in the volcanic ash blown out from Masaya. Both these volcanoes lie eastward of the subduction zone where the Cocos Plate is being over-ridden by the Caribbean Plate at a rate of nearly 7 cm/year. This rate is nearly three times faster than the Cascadia subduction rate, which means that there are proportionally more frequent earthquakes and volcanic eruptions in Nicaragua than in Washington and Oregon. 

I'm just struck by that name: Masaya

~~~~~