With Paul W.S. Anderson’s Pompeii hitting theaters this week, regardless of how the film is received, it could help to once again reignite the public’s fascination with the doomed city that disappeared into memory nearly two thousand years ago. 

The film depicts the final days of the Roman port city with all the flair of a Hollywood film. Star-crossed lovers fight for their lives against an implacable and almost unimaginable enemy that emitted 100,000 times the thermal energy of the Hiroshima nuclear bomb. Anderson’s representation is understandably altered for the sake of an action-hungry audience, but we decided to dig a little deeper and see how close the movie got to reality. So we decided to ask the experts.

The visual effects of Pompeii were handled primarily by Mr. X Inc., a New York- and Toronto-based visual effects studio, whose recent work includes RoboCop, Anchorman 2: The Legend Continues, and Pacific Rim. The company is currently working on the second season of the show Vikings, Guillermo del Toro’s upcoming TV show The Strain, and it is helping with the upcoming Ruseel Crowe film Noah. They often step in to help when needed, but for Pompeii, the studio played a huge part in the filmmaking process.

“We did our best to be historically accurate, we looked at the historical record,” said Dennis Berardi, President and VFX Supervisor for Mr. X Inc told us of the care that went into recreating Pompeii and its demise. “This is 79 A.D., so there’s not a lot of first-person accounts of the events, but there are a couple, including a very important one from a person called Pliny the Younger.” Pliny was no plebeian – his uncle, Pliny the Elder, commanded the Roman fleet at nearby Misenum and died after taking a boat in to help, famously telling his reluctant crew that “Fortune favors the brave.” 

The actual details of the eruption are somewhat lost to history, but a great deal of research gives us well-informed theories. There is debate on when exactly the event actually took place, but the common consensus is that it occurred on August 24.

The eruption began with a minor explosion in the late morning, so minor most didn’t think much of it. Life in Pompeii and neighboring Herculaneum continued with only a minor interruption. Seismic events were common in the area, and this one wasn’t much different. It did encourage a handful of lucky citizens to leave the city before the eruption, but most continued their daily business. Right up until roughly 1 p.m., when the city turned into Hell on Earth.

“It produces things called pyroclastic flows … You can’t run away from them.”

The initial eruption shot ash and pumice into the air, and continued until the sky was so thick with it that the sun was blotted out and eyewitnesses described it as being as black as night. From a ship anchored in the harbor, Pliny the Younger witnessed this and wrote “I cannot give you a more exact description of its appearance than by comparing to a pine tree; for it shot up to a great height in the form of a tall trunk, which spread out at the top as though into branches. … Occasionally it was brighter, occasionally darker and spotted, as it was either more or less filled with earth and cinders.”

This is faithfully recreated in the film, with a mid-day eruption bringing life to a halt, as stunned citizens watched the sun disappear. One of the liberties the film takes, however, is in the destruction of the city by means of molten fireballs that spewed from the mountain. To be fair, this is a visual highlight to a spectacular-looking film, but it didn’t happen that way. The eruption lacked the traditional fire and lava we associate with volcanos. Instead, it was far more deadly.

“It was the type of eruption called plinian, and that’s the same type of eruption Mount St. Helens had in 1980,” Dr. Rosaly M. Lopes-Gautier told us.

Dr. Lopes-Gautier is currently is currently a Senior Research Scientist and Manager of Planetary Science at NASA’s Jet Propulsion Laboratory. She has travelled the globe and visited over 50 volcanos, and now uses that knowledge to study the geology of alien landscapes, including the possibility of ice volcanos on Saturn’s moon, Titan. She is currently acting in support of the film, and helped to explain to us what the actual eruption was like.

“It produces things called pyroclastic flows, which are currents of hot gas and ash that are very, very deadly, and they can travel hundreds of miles an hour,” Dr. Lopes-Gautier told us, describing the plinian type of eruption. “You can’t run away from them.”

One of the major differences between the eruption in the film and the actual event was the speed of the destruction. In the film, the destruction occurs over the course of a few hours. In reality, it went on nearly 24 hours.

“It would have looked like night, but it was daytime,” said Dr. Lopes-Gautier. “Then in the evening of the 24th, that’s when the height of the eruption column increased and went up 20 miles – that’s an estimate. Pumice fall carried on, then around 1 a.m. on the 25th, that’s when the first of what would turn out to be six pyroclastic flows actually came down.”

At around 6 a.m., the first pyroclastic flow hit Pompeii and finished off anyone left. By 8 a.m. the city was effectively gone. An estimated 16,000 people died during the eruption in both Pompeii, neighboring Herculaneum, and the surrounding areas, many of which were covered in more than 30 feet of mud and ash. When the city was rediscovered and excavated in the early 1800s, partially inctact bodies were encased in plaster to preserve them, creating the haunting plaster citizens of Pompeii.

“In the movie they did a good job of depicting the series of events,” said Dr. Lopes-Gautier. “A common misconception is that the volcano just went ‘bang’ all of a sudden, and people died. It wasn’t like that.”

The preservation of the city helped to give us a look at the city as it was, which helped to inform Mr. X and the filmmakers as to how the city was recreated. There were some changes made in the look of the city, including making several of what would have been more average-looking buildings take on an idealized “Roman temple” look, for the sake of making a city that would be more aesthetically appealing to audiences.

“It gets people interested in art and history, and some people are inspired to investigate it a little more deeply and seriously, so I think that’s a positive,””

These changes aside, Mr. X went through painstaking detail to make the film Pompeii as close as it could be to the real city. In the end, the film ended up creating around 20-percent of the sets using traditional methods, while 80-percent of it was CG. Regardless of the mixture, what you see on screen is a faithful representation. The streets, for example, are just a few millimeters larger than the real streets were, and several aerial shots of today’s Vesuvius were used in the film, and then layered with CGI.

Everyday life in the city was also researched and given a layer of reality. We spoke with Professor Sarah K. Yeomans, an archeologist specializing in Ancient Rome, to help us piece together a realistic picture of what the eruption must have been like.

The people of Pompeii were familiar with volcanos, but most assumed Vesuvius was extinct; it had been hundreds of years since the last explosion. Eerily, Vesuvius erupted at least once before in circa 1800 B.C., in what is known as the Avellino eruption. That eruption destroyed several Bronze-Age settlements, and was so powerful that some have suggested it may have been partially responsible for a global shift in the temperature of the Earth.

“We know from Pliny’s letters that there were some organized efforts to get people off the beach. However, for the most part, by the time they realized what was happening, and they realized there was a great deal of urgency in getting these people off the beach, the water had become too tumultuous,” Professor Yeomans explained. “Ships could not land, and those that had landed previously were not able to land again.”

Some of this is depicted in the film, while some yields to the magic of Hollywood and the hunger of the appetites of audiences.

“As an archeologist, there was some license taken with the recreation of the city, but I thought it was spectacular to see an archeological site that I know so well brought to life the way that it was,” Professor Yeomans said. “The CGI technology was fantastic.”

Despite any inaccuracies, she believes the film could end up doing some good.

“It gets people interested in art and history, and some people are inspired to investigate it a little more deeply and seriously, so I think that’s a positive,” Yeomans said.

“We did our best to be historically accurate, we looked at the historical record,”

Regardless of the historical accuracy, the film is spectacular from a visual sense.

The movie’s recreation of the eruption was based on simulations that factored in physics, but some liberties were taken in order to create a better visual output. Still, each simulation was expensive, and each scene typically required multiple simulations, sometimes as many as 15 or 20, in order to find one that fit with what the filmmakers wanted.

“The expulsion of stones, apparently was real,” Berardi said. “The ash plume was real. The blocking out of the sun, because the event happened in mid-afternoon but it was dark by the time it all came down, according to Pliny anyway, was real. And then the blowing off of the top of the mountain and the pyroclastic flow was real.”

Pompeii may not reach the exacting recreation that a film like Titanic did, but it shines a light on one of the most famous disasters of all time, and does so thanks to some incredible effects. And besides, as Professor Yeomans told us, “Anything that gets people interested is a good thing.”