Beneath the Campi Flegrei caldera in Italy, a concealed stratum could account for its persistent restlessness.
Vibrations Underneath Italy's Campi Flegrei Caldera Revealed
It appears the restless rumblings beneath Italy's Campi Flegrei, located close to Naples, originate from a vulnerable layer hidden deep beneath the ground. A recent study suggests this layer, composed of a fragile rock known as tuff, contributes significantly to the caldera's volcanic activity.
According to the research, published in the journal AGU Advances on April 5, this tuff layer is found between 1.8 and 2.5 miles (3 to 4 kilometers) beneath the surface. This light rock, made up of compressed volcanic ash, functions like a sponge for gases emerging from the magma chamber situated at least 7.5 miles (12 km) below. When the pores in the tuff become saturated with these gases, they deform the rock, sometimes even causing it to shatter, leading to earthquakes.
Lucia Pappalardo, a senior researcher at the National Institute of Geophysics and Volcanology in Italy (INGV), and her team believe that their findings could provide a framework for understanding the activity in other calderas worldwide.
Approximately 500,000 people reside in the vicinity that would be impacted by a caldera eruption, endangered by boiling pyroclastic flows of hot ash and gas, as reported by Italy's Civil Protection Department. Campi Flegrei has erupted at least 47,000 years ago and last experienced an eruption in 1538. However, the region has experienced episodes of significant unrest, one of which has lasted since 2005, characterized by numerous, mostly minor earthquakes. On June 5, one of these quakes led to the collapse of a wall at the historic site of Pompeii, reported in the news.
To better comprehend the connection between the structure and strength of the rocks beneath the caldera and its volcanic activity, Pappalardo and her associates examined rocks drilled from deep within the caldera's center decades ago. They identified the minerals and elements in the samples and applied a process called "4D computed X-ray microtomography," which enabled them to observe the rock structure while it was subjected to compression until it cracked. This offered insights into the rocks' strength and mechanical properties.
Intriguingly, their tests revealed the presence of a weak tuff layer, a surprising finding that the researchers are now investigating further. They are exploring how material from the caldera's deep magma chamber may reach the surface, eventually leading to an eruption. While there is currently no indication of a major eruption in the near future, Pappalardo assures that their monitoring system is not registering any signs suggesting magma movement, implying that an eruption may not occur in the immediate future.
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Additional Insights:- Geological and Hydrothermal Activity: Historically, the caldera's hydrothermal system has played a role in ground uplift patterns. However, recent discussions about unrest have focused more on magma movement.- Magma Movement: The recent unrest is characterized by periodic emplacement of magma into a shallow reservoir approximately 3,000 meters deep. This activity is believed to contribute to the observed ground uplift and seismic activity.- Ground Uplift: Rapid ground uplift, previously noted during the 2012-2013 period, is a significant indicator of volcanic unrest, with uplift rates reaching up to 3 cm per month during this period.- Seismic Activity: Renewed seismic activity, including multiple tremors, has contributed to concerns about potential eruptions.
The study on the Campi Flegrei caldera, published in AGU Advances, delves into the connection between the local geology and space-and-astronomy, as researchers investigate how material from deep magma chambers could eventually reach the surface, potentially leading to an environmental-science event like an eruption. Meanwhile, technological advancements, such as 4D computed X-ray microtomography, are being employed to better understand the structure and strength of the caldera's rocks and their contribution to the caldera's volcanic activity.
