delanceyplace.com 4/3/13 - the deadliest volcano in human history

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Mount Tambora Volcano, Sumbawa Island, Indonesia

In today's selection -- in 1815, the deadliest and most powerful volcanic eruption in human history exploded out of Mount Tambora in Indonesia, sending ash eighteen miles into the sky and quickly causing the death of ninety thousand in Indonesia alone. The residue of this volcano quickly circled the earth, dimming sunlight and dramatically lowering temperatures around the globe. This in turn damaged crops and economies around the world and left 1816 to be remembered as the year without a summer:

"Just before sunset on April 5, 1815, a massive explosion shook the volcanic island of Sumbawa in the Indonesian archi­pelago. For two hours, a stream of lava erupted from Mount Tam­bora, the highest peak in the region, sending a plume of ash eighteen miles into the sky. More than eight hundred miles away, Thomas Stamford Raf­fles, the lieutenant-governor of Java, heard the blast at his residence and assumed it came from cannon firing in the distance. ...

"Around seven o'clock on the evening of April 10, Mount Tambora erupted once again, this time far more violently. Three columns of flaming lava shot into the air, meeting briefly at their peak in what one eyewitness termed 'a troubled confused manner.' Almost im­mediately the entire mountain appeared to be consumed by liquid fire, a fountain of ash, water, and molten rock shooting in every direction. Pumice stones -- some walnut-sized but others twice the size of a man's fist -- rained down upon the village of Sanggar, nineteen miles away. After an hour, so much ash and dust had been hurled into the atmosphere that darkness hid the fiery mountaintop from view.

"As the ash clouds thickened, hot lava racing down the moun­tain slope heated the air above it to thousands of degrees. The air quickly rose, leaving behind a vacuum into which cooler air rushed from all directions. The resulting whirlwind tore up trees by the roots and swept up men, cattle, and horses. Virtually every house in Sanggar was flattened. The village of Tambora, closer to the vol­cano, vanished under a flood of pumice. Cascading lava slammed into the ocean, destroying all aquatic life in its path, and creating tsunamis nearly fifteen feet high which swept away everything within their reach. Violent explosions from the reaction of lava with cold seawater threw even greater quantities of ash into the atmo­sphere, and created vast fields of pumice stones along the shore­line. ... [Soon], Tambora's umbrella ash cloud extended for more than three hundred miles at its widest point. ... Twenty-four hours after Tambora erupted, the ash cloud had expanded to cover an area approximately the size of Australia. ...

"By the time the volcano finally subsided, Tambora had released an estimated one hundred cubic kilometers of molten rock as ash and pumice -- enough to cover a square area one hundred miles on each side to a depth of almost twelve feet -- making it the largest known volcanic eruption in the past 2,000 years. Geologists mea­sure eruptions by the Volcanic Explosivity Index, which uses whole numbers from 0 to 8 to rate the relative amount of ash, dust, and sulphur a volcano throws into the atmosphere. Like the Richter Scale for earthquakes, each step along the Explosivity Index is equal to a tenfold increase in the magnitude of the eruption. Tambora merits an Index score of 7, making the eruption approxi­mately one thousand times more powerful than the Icelandic vol­cano Eyjafjallajokull, which disrupted trans-Atlantic air travel in 2010 but rated only a 4; one hundred times stronger than Mount St. Helens (a 5); and ten times more powerful than Krakatoa (a 6). Only four other eruptions in the last hundred centuries have reached a score of 7. ...

"It was also by far the deadliest eruption in recorded history. ... Before the eruption, more than twelve thousand natives lived in the immediate vicinity of Tambora. They never had a chance to escape. Nearly all of them died within the first twenty-four hours, mostly from ash falls and pyroclastic flows -- rapidly moving streams of partially liquefied rock and superheated gas at temperatures up to 1,000 degrees, hot enough to melt glass. Carbonized remains of villagers caught unaware were buried beneath the lava; fewer than one hundred people survived. ...

"In the end, perhaps another seventy to eighty thousand people died from starvation or disease caused by the eruption, bringing the death toll to nearly ninety thousand in Indonesia alone. No other volcanic explosion in history has come close to wreaking di­saster of that magnitude.

"And yet there would be more casualties from Tambora. In addition to millions of tons of ash, the force of the eruption threw 55 million tons of sulfur-dioxide gas more than twenty miles into the air, into the stratosphere. There, the sulfur dioxide rapidly combined with readily available hydroxide gas -- which, in liquid form, is commonly known as hydrogen peroxide -- to form more than 100 million tons of sulfuric acid."