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New research indicates that a volcano near Naples, Italy, is about to prepare for an eruption large enough to alter the landscape of the region.
The study, published today in Progress of science, can particularly interest 1.5 million people living within the limits of the volcanic complex. Fortunately for them, nothing indicates that this massive event will happen any time soon. Volcanic eruptions like this can take thousands of years and there is no way for volcanologists to say when, or even if, this particular type of eruption will occur. Yet it is a fascinating and rare look at the innards of one of the most dramatic phenomena on the planet.
In the study, The researchers found that the molten rock (magma) beneath the Campi Flegrei volcano could slowly turn into a massive eruption, large enough to create a huge depression in the caldera landscape.
Since 1912, only seven events that caused the collapse of caldera have occurred in the world. Campi Flegrei had at least two huge caldera eruptions in its history, one 39,000 years ago that sent nearly 48 cubic miles of magma to the surface and another 15,000 years ago that released 9.6 cubic miles of magma. The latter formed the current caldera at Campi Flegrei, which is more than 13 km wide.
Today, the caldera houses a regional park, cities, suburbs of Naples and a cratered surface that, from time to time, trembles with earthquakes and sends sheaves of sulphurous gas into the air.
For this study, the researchers examined the rocks of these eruptions forming caldera – and 21 smaller eruptions of the same volcano – to determine how the magma reservoirs under the Campi Flegrei had changed over time.
"Understanding what melting below the surface does is very important to help us predict what volcanoes could do in the future," says Janine Krippner, a volcanologist at Concord University in West Virginia. Krippner has not been involved in the research. "It's a really amazing research to see all this data on all these eruptions examined to tell a story."
"Campi Flegrei is very special," says lead author and volcanologist Francesca Forni. Forni began studying the caldera training cycles at Campi Flegrei as a PhD student at ETH Zurich. For geologists, these two caldera training events have occurred relatively recently, over the past 60,000 years.
This "young" age means that the rocks that Forni observed were still relatively cool and had not undergone cycles of damaging deformation and erosion, which could have destroyed valuable data. Campi Flegrei offered an extraordinary opportunity to examine the relatively new idea of caldera training cycles.
"In the past, many studies in Campi Flegrei focused on a single eruption or a period of limited activity. This is the first study that takes into account the magmatic evolution of the system, "explains Forni.
in 1538 an eruption built a 403 feet high hill in a single week
The last time the Campi Flegrei volcano had a major eruption occurred in 1538, when an eruption built a hill high of 403 feet in a single week. The hill is known as Monte Nuovo, or "new mountain". Forni's research indicates that the conditions at this eruption were similar to those that preceded the eruption that caused the formation of caldera.
"In general, the magmas want to burst. They do not like to accumulate in the crust, "explains Forni. Thus, conditions such as temperature, pressure, gas content and the presence of water must all be sufficient for sufficient magma to form and eventually form a caldera. Forni thinks that these conditions could have been fulfilled after the eruption of 1538, which means the volcano could launched another caldera cycle at that time.
But time is a tricky thing when you face cycles that last a lot longer than any life.
"We have no constraints at the moment," explains Forni. "We do not know when it will happen in the future." They know that the previous cycle of the caldera took 21,000 years, but there is no guarantee that the next cycle will take so much time. It is also possible that the volcano simply disappears before creating another caldera. Without more data, there is currently no way to find out.
"Volcanoes are not clocks, either in terms of time or behavior," says Forni.
This does not mean that people should not do their best to prepare for the potential danger of a caldera rash.
"These very big eruptions have an extremely low probability," says Krippner. "But if that happens, we need to know as much as we can." This study adds to this growing body of knowledge about Campi Flegrei.
Krippner and Forni both point out that the activity of Campi Flegrei is extremely closely supervised by local authorities. They also point out that emergency planners are constantly looking for much smaller signs of eruptive activity on the volcano. Preparing for future eruptions, be it giant calderas or something much smaller, is a reality for the people of the region.
"Since there is a city built in this caldera, even small eruptions can be very destructive," says Krippner. "There are 800 million people living near volcanoes in the world and, in this case, they live inside a volcano."
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