Just below millions of people there is a supervolcano that has begun to show signs of reawakening. The supervolcano, Campi Flegrei, is 8 miles wide and sits beneath the Bay of Naples offshore Italy. Recent monitoring of the volcano points to a reawakening of one of the largest volcanoes in Europe.
An international team of geoscientists have monitored the volcano’s caldera for signs of activity and recently published results in the journal Nature Communications on the increased danger of an eruption.
Campi Flegrei, which means “burning fields” in Italian, is believed to have formed hundreds of thousands of years ago and has erupted on several occasions in recent geologic time. The initial eruption, which occurred 200,000 years ago triggered a “volcanic winter” from the massive amount of ash ejected into the atmosphere. The volcano then erupted again 40,000 and 12,000 years ago.
The eruption 40,000 years ago is thought to have wiped out most of the European Neanderthals and was one of the largest volcanic eruptions of all time. In recent memory, Campi Flegrei erupted in 1538 for 8 days straight, sending ash across Europe and forming the new mountain Monte Nuovo.
Recent measurements from the Campi Flegrei volcano indicate it is approaching what is called the critical degassing pressure (CDP), a pressure at which the volcano can begin a phase of volatility and volcanic unrest. The CDP is generally speaking a pressure where volcanic gas can release from the underlying magma, heat localized hydrothermal vents, fluids, and rocks. This increased pressure and heat can trigger deformation of the overburden rock and ultimately rock failure, i.e. a volcanic eruption.
Scientists have measured accelerated deformation of the volcano, which has literally risen recently due to increased gaseous pressures. Scientists have measured a 1.25 feet rise of the volcano’s ground since 2005. Gas at high pressures in the subsurface is exceptionally dangerous as it can easily and quickly lead to an unconstrained positive feedback loop. Imagine gas in solution in magma, which is relatively stable.
If that gas begins to escape and rise in the Earth’s subsurface through magma, the gas will subsequently reduce the overlying pressure of the magma below it. That in turn allows for more gas to come out of solution and rise in the magma column. In an instant, you can have a runaway situation whereby decompressed gas allows for more decompression and an eventual blowout. This is not dissimilar to some situations seen during oil and gas well blowouts.
The location of Campi Flegrei is especially alarming, located immediately near the metropolitan area of Naples, a very densely populated metropolitan area. The volcano is therefore actively monitored by the Italian National Institute of Geophysics located in Rome, where real time measurements are analyzed for increasing threat.
Despite the increasing signs of activity, it’s very hard to determine the “tipping point” at which the volcano begins erupting. However, the Italian government recently raised the volcano’s threat level from green to yellow, which requires constant scientific monitoring for changes in volcanic behavior. The most common signs of increased likelihood of an eruption are increased gas output (decreased gas pressure), elevation rise on the volcano’s surface, and increased seismicity within the volcano.
Unfortunately, the best thing we can currently do is actively monitor the volcano for signs of further increasing activity. However, an eruption could not happen for the next century, it’s impossible to accurately model when these events will occur. Similar to many geologic processes on Earth (earthquakes, volcanic eruptions, sinkholes, etc.) the signs of decreasing stability are easy to detect but the tipping point at which the event occurs is very hard to predict.
Courtesy of chiangraitimes.com