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. 

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