INGV and CNR: satellites and GPS to study the flow of magma under the Campi Flegrei

A new technique, signed by INGV and CNR, capable of calculating, through satellite and GPS data, the ways in which the deep magma rises within the subsoil of Campi Flegrei, creating deformations, even millimeters, of the earth's surface. A mechanism probably common to other calderas (Yellowstone in the USA and Rabaul in Papua New Guinea). The study, published in Scientific Reports, provides new monitoring systems useful for dealing with any future volcanic crises

The data acquired by the satellites and GPS receivers of the network of sensors present in the Campi Flegrei area are used to monitor the deformations of the earth's surface and know, in real time, the trend of the uplift of the soil inside the caldera. It is the new monitoring technique developed by a team of researchers from the Vesuvius Observatory of the National Institute of Geophysics and Volcanology (INGV-OV) and the Institute for Electromagnetic Sensing of the Environment of the National Research Council (CNR- IREA), to better understand the uplift phenomena that have occurred in recent years at Campi Flegrei. The study, which is part of the monitoring activities promoted by the National Department of Civil Protection (DPC) and those carried out within the European project MED-SUV (MEDiterraneanSUpersite Volcanoes), was published in Scientific Reports.
“Thanks to the data acquired by the COSMO-SkyMed satellites (put into orbit by the Italian Space Agency since 2007), equipped with radar systems, and by the GPS receivers of the INGV-OV geodetic surveillance network, made up of 14 sensors scattered throughout the 'area of ​​the Campi Flegrei”, explains Susi Pepe, researcher of the CNR-IREA, ventim “it was possible to study the deformations, even millimeters, of the earth's surface and to know the trend of the uplift of the soil inside the caldera”.
Over the past millennia, the Campi Flegrei caldera has produced eruptions of gigantic dimensions: forty thousand years ago that of the Ignimbrite Campana and fifteen thousand years ago that of the Neapolitan Yellow Tufo, which caused the superficial part of the volcano to collapse for hundreds of metres, forming the current structure.
"After the last eruption of 1538, which produced the crater of Monte Nuovo", says the researcher responsible for the Monitoring Room of the Vesuvius Observatory of the INGV, Luca D'Auria, "the soil of Campi Flegrei began to sink slowly for centuries, interrupting this trend around 1950, when the Phlegrean area started to rise again. This phenomenon, known as bradyseism, manifested all its violence between 1982 and 1985, a period in which the ground rose by almost 2 meters, accompanied by earthquakes, causing the evacuation of thousands of inhabitants of the city of Pozzuoli. In 2005 the ground began to slowly rise again, and low-magnitude earthquakes reappeared”.
In the last 10 years the ground has risen by almost 30 cm., so much so that in December 2012, on the basis of the assessments of the Major Risks Commission, the Civil Protection Department raised the level of alert of the Campi Flegrei, with the consequent strengthening by INGV of the monitoring of the volcano.
“Regarding the origin of the Phlegrean bradyseism”, continues D'Auria, “the scientific community agrees on the fact that between 1985 and 2012 the uplift of the ground was linked to the introduction of hydrothermal fluids (water and gas) inside the rocks of the caldera and the progressive warming of the latter. On the most recent episode of uplift, between 2012 and 2013, the phenomenon would instead be attributable to the ascent of magma at a low depth (about 3 km) which is injected into the rocks of the subsoil forming a thin layer, known as sill, a small 'underground lake', with a radius of 2-3 km. The sill was already present in the subsoil and was probably active during the bradyseismic crises of the past decades when quantities of magma, even ten times higher, arrived in this small superficial magma chamber".
The magma within the sill, however, can cool rapidly, therefore making it less capable of producing eruptions. This mechanism, observed at Campi Flegrei, is probably common to other calderas (for example Yellowstone in the USA and Rabaul in Papua New Guinea) and could explain some apparently "bizarre" behaviors observed in these volcanoes.
"Prediction of volcanic eruptions in calderas is sometimes more difficult than in other volcanoes", adds D'Auria of INGV. "The ascent and intrusion of magma into sills could, in fact, be the normal life cycle of calderas."
The results of the study are of great importance for the interpretation of the data acquired by the new generations of satellites (such as those of the SENTINEL constellation of the European Copernicus Program, operated by the European Space Agency - ESA) and by the innovative geophysical monitoring technologies at Campi Flegrei .
"These new monitoring systems, integrated with the new analysis methodologies, can provide a useful tool to deal with any future volcanic crises in Campi Flegrei", concludes Susi Pepe of the CNR.

Image link: http://bit.ly/1hBLv2w

Link to the article: www.nature.com/articles/srep13100