Nightmare at Naples

Have you ever watched one of those television shows about Pompeii? Pompeii and its neighbor Herculaneum were Roman-era towns at the foot of Mt. Vesuvius, an active volcano adjacent to the now Italian city of Naples. In 79 AD, Vesuvius erupted and quickly buried the two places. The old towns lie forgotten for nearly two millennia. It wasn’t until the 18-century that a farmer digging a water well discovered, at the bottom of the hole, a Herculaneum house with finely tiled walls. Not long after, diggers encountered dozens of curious voids in the deposits. Deciding to fill those voids with plaster and later strip away the surrounding ash, they were presented with astonishingly detailed casts of men, women and children. These were Pompeii people trying, but failing, to escape Vesuvius doom. 

To me as a kid, seeing those plaster figures on then black and white TV had real effect. How could something happen so fast as to snare all those people in flight? I’ve blogged here before about volcano hazards-- lava flows and lahars --but what caught Pompeii unprepared was pryoclastic flow. Some volcanic eruptions blow millions of tons of hot ash 1000s of meters into the sky.  For a while, updrafts suspend the mass in a mushroom cloud. Eventually outgassing slows and gravity holds sway. The terrible weight of the suspended cloud comes crashing to Earth and down volcano slopes at 100 miles per hour. Pryoclastic flow doomed the Pompeiians.

In 79 AD the area around Vesuvius housed perhaps 50,000. Today, Naples and nearby host 5 million. Let’s hope that 2000 years from now, some farmer digging a well does not discover voids of current residents caught again unawares.

Steven N. Ward   Santa Cruz