My friend, Joy, gave me two books to read about volcanoes.  They were highly interesting.  They need to be summarized.

Volcanoes are a natural phenomenon that can, has, and might again change the world.

Millennia ago the hot spot that's currently under Yellowstone National Park was in southern Oregon.  As the continent slowly drifts over it to the west, the hot spot stays put.  Yellowstone moved clear across Idaho, roughly following the Snake River, and is now in the northwestern corner of Wyoming.  It is one of the world's super volcanoes

Volcanic eruptions are rated by the Volcanic Explosivity Index (VEI) on a scale from one to eight, with eight being the largest.  Each successive number is 10 times more powerful than the preceding number.  Yellowstone's eruptions were likely 8's.  In Nebraska  there is a field full of ancient rhinoceros skeletons.  It is thought that the herd was probably killed by an eruption of the Yellowstone super volcano, 900 miles away.

The Mount St. Helens eruption was a VEI 5.  The most recent Yellowstone blowout is thought to have been 2,500 times the size of the 1980 eruption of Mount St. Helens.  The oldest Yellowstone eruption was 6,000 times bigger than the St. Helens eruption.

The destructive power of volcanoes is in lava flows, hurled rocks, lihars, pyroclastic flows, ash fall, tsunamis, clouds of toxic gas, and in the amount of particulate matter that gets ejected into the stratosphere.  I've listed those hazards in roughly their increasing order of destructivity.  Lava flows and hurled rocks are dangers near the volcano.  The other hazards are more far reaching.

Lihars are sudden flash floods that burst out from under glaciers that are typically found on high volcanoes.  Hot magma rising beneath a glacier melts the ice.  Water pools beneath the glacier until it finds an escape route, and then comes out with a rush.

Pyroclastic flows are sudden surges of hot gas, ash, and rock fragments that move at great speeds over many miles.  It is a fluid-like avalanche that can suddenly engulf a town and obliterate it.  This happened on Martinique, an island in the Caribbean Sea in 1902.  Every soul but one in the city of Saint-Pierre, a city of 30,000 people, perished.  The one survivor was a convict in jail.

Ash from a volcano can be carried by the wind for hundreds or thousands of miles.  The ashfall from the explosion of Mt. Mazama in southern Oregon 7,000 years ago left deep deposits of ash all over the Pacific Northwest and into Montana.  The eruption of Mt. Vesuvius in 79 C.E. buried Pompeii so completely in ash that a short time later history forgot that the city had ever existed.

Tsunamis generated by volcanoes can be devastating hundreds or a thousand miles away from the source.  Krakatoa blew up in Indonesia in 1883.  Krakatoa was a high mountain on an island.  It erupted for 100 days.  Many of the eruptions sent out a new tsunami.  36,000 people were killed by the waves.  Its biggest eruption was heard 2,000 miles away, and is thought to be the loudest sound ever heard on earth.  When Krakatoa was through erupting, the entire island had sunk beneath the sea.

Even more far reaching than tsunamis are the clouds of toxic gas that a volcano can emit.  On 10 June 1783 a haze appeared in Norway and France.  Eight days later it was a fog which had covered France and reached Switzerland and Italy.  It limited visibility, and was foul smelling.  Winds were unable to disperse it.  It lasted all summer and into October.  1783 was before worldwide communication was possible, so Europe was unaware that the Laki volcano in Iceland was erupting and causing the dense haze.  The haze had “a sulphurous stench, burned the eyes and throat, and left a bitter taste in the mouth.”  (Island on Fire, pg. 110-111, Alexandra Witze and Jeff Kanipe).

Europe experienced a spike in deaths during this period, not unlike deaths caused by the plague.  It is difficult to say how many of the deaths were caused by the foul air, but estimates range from 1.5 million to as high as six million.  (Ibid, pg. 145).

The most long-lasting and dangerous effects of a major volcanic explosion lie in how high the gas and ash plume goes.  If the gases and ash reach the stratosphere the effects can be carried worldwide and last for years.  There is no rainfall in the stratosphere to clear the air.

We live in the troposphere.  Above the troposphere is the stratosphere.  The troposphere is thicker in the tropics than at the poles.  The troposphere in the tropics extends about eight miles above the earth.  At the poles it transitions to the stratosphere at about 3 ½ miles above the earth.  Major volcanic eruptions nearer the poles, therefore, are potentially more dangerous than those that occur in the tropics because gases and particulate matter don't have as far to go to reach the stratosphere.  A volcano like Laki, in Iceland, might, therefore, be more worrisome than a volcano in Indonesia.

It all depends upon the strength of the explosion.  In April 1815 Mt. Tambora erupted in Indonesia.  It was a VEI 7 eruption, the greatest in recorded history.  The blast sent material 18 miles high, into the stratosphere.  The formerly 12,000-foot-high mountain lost over one-quarter of its height.  Material from Mt. Tambora circled the globe for years causing frosts, crop failures, and famines in China, Europe, and the northeastern United States.  It was the cause of the “year without a summer” (1816) which caused the family of Joseph Smith Sr. to lose their farm, and which precipitated their move to western New York.  70,000 people were killed by the explosion, but millions more deaths were caused by the resulting famines.

Which all makes me wonder about the three days of darkness in the Americas which was occasioned by the death of Jesus Christ, as recorded in the Book of Mormon.  The storm, darkness, and upheaval had been prophesied, and were watched for.  When they came, “the face of the whole earth became deformed” … and “there was thick darkness upon all the face of the land, insomuch that the inhabitants thereof who had not fallen could feel the vapor of darkness.”  (3 Nephi 8:17, 20).  Do you suppose that the earthquakes and tempests were accompanied by erupting volcanoes?  It seems likely.  Do you suppose that geologists and archaeologists could look for, find, and date ash layers in the mesoamerican area that would correlate with the time frame of 34 A.D.?

Volcanoes were major players in the formation of the earth.  They continue to impact our lives, sometimes for worse, and sometimes for better.  The ash from volcanoes created much of the fertile soils that we depend upon.  Mt. Tambora was also the means by which young Joseph Smith Jr. was put in juxtaposition with the Hill Cumorah.  But for Mt. Tambora we might not today have the Book of Mormon.