South America’s Biggest Volcanic Eruption

By that term we mean that such an eruption sends ash, smoke, and fragments of volcanic rock with terrific force high into the atmosphere, frequently as high as twenty-five miles. Places within fifteen miles of the Arequipa volcano were devastated. The neighboring states of Chile and Bolivia received thick layers of ash, as did Lima, the capital and largest city of Peru. Later, ruins revealed the details of the communities that had been smothered by ash and rock fragments, just as Pompeii had been by a similar event in the year 79. The name Plinian was given to this type of eruption in honor of Pliny the Elder, the famous Roman who was killed when Mount Vesuvius erupted, killing him and most of the people of Pompeii.

Drainage, lakes, and transportation routes were all affected because of the huge amount of material that fell on them. In addition to the human losses, the loss of farmland, vineyards, crops, livestock, and water supplies completely disrupted the economy of the area. There were no international trading links, and no manufacturing or similar occupations to which people could turn in 1600 for their survival. They depended totallyon what they could obtain from the ground. Fortunately, recovery was undertaken immediately. Arequipa was rebuilt and within a few years farming activities were close to pre-eruption standards, largely the result of life being very simple. In recent times, mainly through examining underground evidence of past climates, scientists have come to see that the impact of Arequipa was far greater than local records from 1600 would suggest.

It affected countries all over the world. A few scientists said that it contributed to a worldwide cooling that occurred in the summer of the year 1601, the coldest summer within the past five hundred years. The eruption was preceded by a series of earthquakes and explosions as magma made its way upward toward the surface. The volcanic mountain that was about to explode stood more than 13,000 feet high within the upper reaches of a broad valley. It had three vents high above the valley through which gas, smoke, and pumice was about to escape. Each one of the three was huge, about 300 feet deep and over 250 feet in diameter. The setting of the mountain was equally impressive, a valley that had been carved out of an ancient volcano’s side and summit, a horseshoeshaped amphitheater that looked like a glacial cirque. It is clear from the evidence that is being uncovered at the present time that the area around Arequipa experienced numerous volcanic eruptions over the past few millions of years.