Thursday, December 3, 2020

Land of Volcanoes and Earthquakes – Part I

If we take Mormon and the Disciple Nephi at their word, we have to conclude that there were numerous volcanoes in the Land of Promise. First of all we need to understand what causes volcano eruption.

Whenever a volcano acts up, earthquakes are one of the first signs. In fact, earthquakes and volcanoes are intimately linked, both are products of the plate tectonic process that is constantly reshaping the surface of the Earth. But even beyond that, earthquakes are some of the best clues we have that magna is on the move, and a volcano is heading toward an eruption (Erik Klemetti, “What's Up With the Quakes Before a Volcano Erupts?” Science, Wired, Condé Nast, Advanced Publications, New York, 2015).

Earthquakes happen under volcanoes because Magma, which is the source of volcanism in almost every volcano on the planet, is initially formed by melting the mantle, 5 to 50 miles beneath the surface.

When volcanoes erupt, magma is liquid rock within the interior of the Earth, but as the molten rock finds its way to the surface, we refer to it as lava—thus the main difference between magma and lava is location.

Magma is generally thought of as a liquid, but it is a very dense and viscous liquid compared to something like water, which means it can exert a lot of force on the rocks around it as it rises its way through the crust. This is what generates much of the earthquakes that occur in volcanically active areas since the magma is buoyant, because it is hot, chock full of gases and made of less dense material than the rock around it, so the fluid pressure from the rising magma cracks the rock, making space for itself as it rises, taking the easiest path out of the crust.

In fact, they are called volcano tectonic earthquakes, one of three types of earthquakes associated with volcanic eruptions—the other two are Long-period  earthquakes and harmonic tremor earthquakes. In addition, places with abundant volcanoes also tend to be riddled with faults, so earthquake swarms that are tectonic are common. Thus, generally speaking, the earthquake and volcanic eruption work together and both are connected to create the “shaking of the earth.”

As Mormon put it in abridging the Disciple Nephi’s account:

• “And there was also a great and terrible tempest; and there was terrible thunder, insomuch that it did shake the whole earth as if it was about to divide asunder” (3 Nephi 8:6, emphasis added);

• “There was a more great and terrible destruction in the land northward; for behold, the whole face of the land was changed, because of the tempest and the whirlwinds and the thunderings and the lightnings, and the exceedingly great quaking of the whole earth” (3 Nephi 8:12,emphasis added);

• “Many great and notable cities were sunk, and many were burned, and many were shaken till the buildings thereof had fallen to the earth” (3 Nephi 8:14, emphasis added);

• “Ihus the face of the whole earth became deformed, because of the tempests, and the thunderings, and the lightnings, and the quaking of the earth” (3 Nephi 8:17, emphasis added);

• “The thunderings, and the lightnings, and the storm, and the tempest, and the quakings of the earth did cease” (3 Nephi 8:19, emphasis added).

All of this, including the “shaking of the whole earth,” meaning earthquakes in the Land of Promise, happened over a three-hour period, though it seemed much longer to the Nephites in the land (3Nephi 8:19). In fact, this earthquake broke huge slabs of solid rock that were rent in twain—split into two pieces—they were broken up upon the face of the whole earth, insomuch that they were found in broken fragments—rocks broken into pieces, and in seams and in cracks, upon all the face of the land.

When volcanoes erupt, magma is liquid rock within the interior of the Earth, but as the molten rock finds its way to the surface, we refer to it as lava—thus the main difference between magma and lava is location


In addition, Volcanic activity and volcanic eruption is usually triggered by alterations of tectonic plates, where tectonic plates diverge or converge, volcanoes can be found, resulting in landslides or earthquakes. A volcano has a number of toxic gases possibly present in pyroclastic (fragments of rock) material. The effects of volcanic eruption are likely felt globally or at least by a whole hemisphere. Large areas will be devastated by pyroclastic flow deposits, and the more widely dispersed ash falls will be laid down over continent-sized areas. The most widespread effects will be derived from volcanic gases, and sulphur gases being particularly important.

Sulfur Dioxide, carbon dioxide and other sulfur oxides, as well as significant amounts of hydrogen sulfide and hydrogen halides, hydrochloric acid can react with other compounds in the atmosphere to form fine particles that reduce visibility (haze). This haze is a thick cloud of tiny water droplets suspended in the atmosphere at or near the earth's surface which obscures or restricts visibility.

Sulfur Oxide (SO2) also has a great potential for long range transport since gases may remain in the atmosphere for several days, during which they can travel over large distances together with cross-country monsoon phenomenon

The Byzantine historian Procopius of Caesarea was a prominent late antique Greek scholar from Palaestina Prima, wrote that in 536 AD: “a most dread portent took place during a massive volcanic eruption, for the sun gave forth its light without brightness and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear.” This darkness caused the most severe global dimming in the past two millennia, and seems without question that a volcano was to blame for the darkness. The atmosphere became shrouded in a haze of dust, which is known to happen after large volcanic eruptions.

The Ash cloud can block out sunlight over a large area


A dust veil of appeared after the eruptions of Tambora in Indonesia in 1815, and of Mount Pinatubo in the Philippines in 1991. According to Keith Briffa, a palaeoclimatologist at the University of East Anglia in the UK, who states: “Any normal interpretation of the data would point to a volcanic origin,” though no one has previously been able to find clear evidence for that, leaving room for other theories.

However, Briffa and his team  recently found the characteristic fingerprint of a volcanic eruption in layers of ice in the Greenland and Antarctic ice sheets, narrowly dated to 533-536 AD, and claim the eruption happened in 535, and that its effects were felt in the Northern Hemisphere in the following year (Larsen, L. B. et al., Geophysical Research Letters 2007).

This fingerprint takes the form of sulphate ions, formed from the sulphur dioxide released by volcanoes. Meteorite impacts do not tend to release sulphur into the atmosphere unless they happen to hit sulphur-rich minerals.

The fact that a sulphate layer can be seen not only in the northern but also the southern polar region implies that the eruption probably happened close to the Equator, so that its dust was dispersed all over the Earth. But the north bore the brunt of the climate effects – there’s no sign of cooling in geological records from New Zealand, for example (Lee Siebert, et al., Volcanoes of the World, Vol.3, Smithsonian Institution, Global Volcanism Program, University of California Press, Berkeley, California, , 2011).

The 536 AD dust veil of aerosols (consisting mostly of tiny droplets of H2SO3 acid, formed by SO2 release) and ash (a mixture of very small [0.079 inches] rock, mineral, and glass particles expelled from a volcano during a volcanic eruption. The most abundant gas typically erupted during a volcaniceruption is water vapor, which has been measured to be as high as 97% percent of gases erupted from some volcanoes. In addition, dry fogs, which are caused when warm, moist air passes over a cool surface.

In the atmosphere, the fluid is wind. When the moist, warm air makes contact with the cooler surface air, water vapor condenses to create a dense fog. In addition, this fog appears in the atmosphere when large volcanic eruptions inject massive quantities of fine silicate ash and aerosol-forming sulphur gases into the troposphere and stratosphere. This ash is dissolved gases in magma that expand and escape violently into the atmosphere from a volcano, and the event in 536 AD was more severe and produced more protracted dimming than was observed after the Tambora eruption.

Measurements from ice cores from both hemispheres allowed Briffa and his team to conclude that tropical volcanic eruption, which caused the 536 dust veil, was of somewhat larger magnitude than the 1815 Tambora eruption on the island of Sumbawa in present-day Indonesia—considered the most powerful volcanic eruption in recorded human history, as far as is known, resulting from movement of plate tectonics.

Briffa explains that, although it’s not hard to spot such sulphate contamination of ice in principle, the hard part is constraining the dates of the layers enough to link them to the tightly dated tree-ring evidence of cooling, and to distinguish them from sulphate that came from smaller but nearer eruptions. This careful detective work was carried out by Bo Møllesøe Vinther and his co-workers at the Niels Bohr Institute, University of Copenhagen, Denmark. 

(See the next post for more on matching 3 Nephi 8)

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