Volcanism

 

Unfortunately, the name Pompeii is now marred by the painfully embarrassing abomination that was Pompeii, that is, the movie. The movie should really have been titled Gladiator: The Lower-Budgeted Remake With Less Talented Actors.

Admittedly, the title doesn’t roll off the tongue as easily as Pompeii. Nonetheless, you get my point. Lucky for me, I had had enough tequila before seeing the movie to stand most of it before leaving. Unlucky for me, even the tequila could not hide how awful the film was. The whole hour I sat through all I could think about was how disappointed I was that the volcano had yet to make an appearance, and that there was hardly a mention of it until the last ten minutes. Of course, the last ten minutes they manage to fit in a major volcanic event.

They missed a few things, no doubt. Fortunately for you, I’m here to fill in the gaps.

First thing’s first: Mount Vesuvius did not erupt (on that particular event) at night, rudely interrupting a promising developing love story. Sorry to disappoint those of you who were banking on that.

I’ll get more into the eruption and the events of August 24 and 25 soon, but before that, we must familiarize ourselves with the volcano.

Mount Vesuvius is a composite cone (like Mount St. Helens, Mount Lassen, Mt. Mazama, etc.), and its cone sits in the caldera of the Somma volcano (which hasn’t erupted in about 17,000 years). Vesuvius is part of a line of volcanoes in Italy, but is the only one actually active. In fact, Mount Vesuvius is the only active volcano in mainland Europe.  This line of volcanoes, called the Campanian volcanic arc, is a result of the convergence of the African and Eurasian tectonic plates. If you remember any of the facts of the eruption in 79 AD,  you’ll know the eruption was destructive and catastrophic for the surrounding cities. Now, remember the discussions on Mount St. Helens and Lassen, particularly the fact that both produced violent eruptions, and the reasons why.

Mount Vesuvius produced mainly andesitic lava flows. Andesite has a high silica content (53-63%), which means the flow is thicker, higher in dissolved gasses that get trapped inside the magma and expand, making the eruption more explosive. To make matters worse, Vesuvius is known for producing large columns of ash, gas, and rock, known as Plinian eruptions (named after the Roman historian Pliny the Younger, who wrote the oldest known description of these volcanic events), which can reach high into the atmosphere. Because these plumes reach so high, winds disperse the dust, ash, and rock to surrounding cities, like with Pompeii and Herculaneum (“Mount Vesiuvius – Italy”, Bell).

Now that you know a little more on the nature of the volcano, you’ll have a better understanding and, hopefully, appreciation for the events surrounding Vesuvius’s most famous eruption.

On the morning of August 24, 79 AD, most likely eruptions of steam shot from the volcano preceded later volcanic activity. Several hours later, violent columns of ash and dust followed, reaching Pompeii (9 kilometers from Vesuvius) later that day. The ash and pumice continued to fall, leaving those who had not yet evacuated trapped inside the city. The large pieces of rock and pumice that fell damaged the roofs of many homes and other buildings, making evacuation impossible for remaining survivors.

On August 25, hot dust and gas swept from the volcano, killing those in Pompeii and Herculaneum who had survived through the night. In total, approximately 16,000 people were killed. The two cities were covered in 3 meters (around 10 feet) of ash. As the hot ash covered those remaining, their bodies – including their clothes and facial expressions – were perfectly preserved in the moment of death. Afterwards, rain cemented and hardened the ash, creating a cast before decomposition could occur. Once the body decomposed, a pocket in the shell of solidified ash remained.

       

It wasn’t until 1595 that Pompeii and Herculaneum were excavated, revealing a preserved city and all those who died within it (including pets). The excavation of these cities not only unearthed an important event in history, but helped tell the sequence of events, which would later lend a greater understanding for Vesuvius’s eruptive history (60, 94-95).

I remember reading about Pompeii in elementary school and being absolutely fascinated by the destruction and devastation of the city. The pictures of preserved humans and animals were disturbing, but in the way that keeps one from looking away. Since then, I’ve kept Pompeii and Mount Vesuvius in the back of my mind, as a most necessary place to see in person.

If not for the volcanoes, go to Italy to eat food, ride a Vespa, fall in love. Or whatever it is you do while visiting Italy. Either way, nothing is lost and much is gained.

Adventure on, dear readers.