The Mysteries of Mt. Etna UNVEILED

The Mysteries of Mt. Etna UNVEILED

Earthquake destruction is the primary local threat from the Mt. Etna system.

(Photo courtesy of Giornale Di Sicilia)

( U.S. Navy photo by Janine Scianna)

October 30, 2002 eruption of Mt. Etna as seen from the International Space Station

(NASA photo)

By Janine Scianna NAS Sigonella Public Affairs

She stands tall on the horizon, no matter where you are in eastern Sicily. Her presence may be a daunting sight when you first arrive at Sigonella, but as time goes by, fear gradually disappears and is replaced with the feeling of having a friendly presence in your backyard. Indeed, according to Dr. Boris Behncke, volcanologist at Catania’s Istituto Nazionale di Geofisica e Vulcanologia, Mt. Etna is often considered to be the physical embodiment of a mother to Sicilians. For the most part, her near-constant activity has acted like a slow pressure release, and damaging eruptions and earthquakes have been fairly infrequent in modern history.

Yet, Behncke says the illusion of Etna as a “friendly volcano” is the number one myth he’d like to dispel.

“It’s the mother of the people here. But sometimes a mother gets grumpy, and every once in a while she punishes,” warned Behncke.

The good news is that even with this inherent danger, the risks can be mitigated by smart policy choices.

Sigonellans don’t have to reach deep into their memories to find evidence of the dual threat of volcanism and earthquakes from Mt. Etna. The Christmas Eve 2018 eruption flung ash high into the air, and just two days later, a 4.9 magnitude earthquake followed, causing structural damage to mountain towns.

Mt. Etna, as Behncke describes, is one of the most versatile and varied volcanoes on the planet. She can erupt like almost any other style of volcano, from the peaceful, effusive flow of the Hawaiian style to the explosive, Plinian-style of Mt. Vesuvius. In fact, geologic evidence shows that a Plinian eruption occurred as recent as 122 B.C., when a “champagne effect” allowed for instantaneous, explosive decompression of the magma chamber.

The primary variable that dictates how Mt. Etna erupts is the gas content. A lot of gas in the magma can cause more violent explosions. If that gas finds a way to gradually release over time, then the eruptions can be peaceful.

Behncke is quick to point out that even with the best science and monitoring, it is difficult to really know when the next big eruption will occur. But Behncke says there are signs that indicate that she is preparing. Magma has been accumulating deep in the chamber, and the December eruption could have been the first in a series of flank eruptions—where magma is released out of secondary vents away from the summit. It is continuously a surprise to see where the next eruption will occur at. In fact, Etna has over 300 craters and holes where eruptive activity has taken place. And if Behncke is right, the upcoming eruptions in the series will likely be stronger than the first, and it might happen in the next 1-2 years.

Yet, even with a large eruption possible in the near future, Behncke says that the sheer size of Etna makes the threat of encroaching lava and dangerous ash fall minimal. He says that there is “zero chance” of lava entering the city of Catania ever again—there simply is “too much stuff in the way.” In fact, the last time lava got close to a populated area was in 1981, when Randazzo narrowly escaped an eruption. Compared to a volcano like Mt. Vesuvius, which is much smaller in size and has densely populated areas on its flanks, the risk of Mt. Etna’s eruptions causing damage to populated areas is diminished.

Even though eruptions are sensational and draw most of the attention and fear, Behncke warns that earthquakes are the most imminent danger. In fact, it was the 1693 earthquake that demolished the city of Catania, not an eruption.

Earthquakes can occur on their own or in conjuction with an eruption. Mt. Etna’s earthquakes tend to be capped at a magnitude of around 5.0 on the Richter scale. This is because the faults in her system are shallow and short compared to a fault zone like the San Andreas. But the magnitude of an earthquake has much less to do with the resulting damage than how quickly the seismic waves accelerate, and what type of structures the seismic waves propagate through

Behncke says that only 50-80 percent of Catania’s buildings are estimated to be capable of surviving a 7.0 magnitude earthquake. That’s because many buildings erected in the 1950-1970s were built cheaply and quickly, with little consideration for earthquake risk.

In addition to conducting research to further understand the complexities of Mt. Etna, Behncke also spends a lot of his time educating the community to build earthquake safety awareness and advocating for government officials to enact policy changes that mitigate earthquake hazards.

“Vote for politicians that promise to make this land earthquake-safe,” advises Behncke. “If there are no such politicians, create them. Become them yourselves.”

For Sigonella citizens, Behncke’s advice for avoiding risk when selecting a home is simple. Avoid renting in a building that was built in the 1950s-1970s, and if possible, choose a home that was built after 1980. That’s when Italy instituted building codes that would prevent homes from collapsing. And of course, avoid towns that are situated close to Etna’s summit, as the threat of lava is highest there.

In a nutshell, if you can make smart decisions about where you live, there is very little chance that Etna could endanger after being you. relieved While innately dangerous, d to Etna NAS can Sigonella. truly be perceived as a mother to Sicily, if she is respected.