Further reading for Campi Flegrei, Southern Italy
Campi Flegrei (also referred to as Phlegrean Fields) is a volcano located in southern Italy, immediately north-west of the city of Naples. The structure is not that of a more classical stratovolcano (a more or less regular cone surmounted by a volcanic crater), instead that of a large, 12x15 km caldera, this being a vast depression originated by a structural collapse following one or more large-scale volcanic eruptions. The Campi Flegrei caldera has been largely filled by volcanic products from eruptions originated after the caldera formation, so that the general appearance to-date is that of a generally flat area punctuated by several post-caldera volcanic craters.
The eruptive history of Campi Flegrei is dominated by the two large eruptions of the Campanian Ignimbrite (ca. 39,000 BP) and Neapolitan Yellow Tuff (ca. 15,000 BP). These eruptions discharged about 300 and 50 km3 of magma (DRE), respectively, and produced pyroclastic flows that completely devastated an area up to tens of km from the caldera. Additionally, the eruptions produced significant ash accumulation on the ground up to hundreds of km from the vent area. Both eruptions are likely to have had a substantial impact on the climate at global level.
After the Neapolitan Yellow Tuff eruption, the volcanic activity at Campi Flegrei has concentrated in three discrete periods, called “epochs”, between approx. 10,500 and 9,500 BP (first epoch), 8,600 and 8,200 BP (second epoch), and 4,800 and 3,800 BP (third epoch). A total of more than 60 eruptions make up these three epochs of activity, most of which characterized by a markedly explosive character.
The last eruption occurred in 1538, and was among the smallest recorded in the eruptive history of Campi Flegrei. This eruption interrupted a period of quiescence of more than 3,000 years, and in about one week it originated the Monte Nuovo (= “New Mountain”) cone, about 130 m high. Since then, the activity at Phlegraean Fields has been mainly characterized by bradyseism (slow upward or downward motion of the caldera floor), and fumarolic activity mainly located in the Solfatara crater.
Since the 1950s the Campi Flegrei volcano is in a state of unrest, characterized by discrete (months to years) periods of caldera floor up-rise accompanied by seismic swarms and shortly followed by significant changes in the composition and flow of fumaroles. The latest crisis occurred in 1983, when about 40,000 people were evacuated from the town of Pozzuoli. During last ten years there have been several minor uplift phases, each accompanied by seismic swarms, and a general intensification of the fumarolic outflow that overall contribute to substantial concern for a possible reappraisal of the volcanic activity in the area.
The word "Flegrei” (“Phlegraean") comes from the greek flègo = "to burn", but it does not refer to volcanic eruptions since during the Roman times, and for more than one thousand years before, the volcano was dormant. The attribute "Phlegraean" is due instead to the presence of fumaroles and hot springs, well-known since ancient times. The area has been always surrounded by myths and legends. The very famous “Sibilla Cumana” (“Cumaean Sibyl”), whose relevance is codified in Virgil’s Aeneid, provided predictions to ancient Roman kings and warlords from her antrum at Campi Flegrei. The Averno crater and volcanic lake, inside the caldera, were identified in Roman mythology as the entrance to the Underworld.
More than 300,000 people live inside the caldera of Campi Flegrei, that includes part of the same city of Naples (about 1 million people). Together with the present unrest state of the volcano, and the predominantly explosive nature of its eruptions, that puts the area among those with highest volcanic risk worldwide. That risk is even increased by the presence of the Vesuvius volcano, on the East side of Naples.
- Seismic stations for monitoring of seismic events over a broad range of frequencies;
- Geochemical stations to measure the temperature of fumarolic gases;
- GPS, clinometric and dilatometric stations for the detection of ground movements;
- Webcams (visible and infra-red) for direct observations.
In addition, periodic surveys are carried out to measure gravity changes, to execute EDM leveling, to take additional geochemical measurements including composition and flow of fumaroles, and to execute specific seismic and/or electro-magnetic experiments.
Under agreements with the Italian Space Agency (ASI), multiparametric analysis tools have been implemented to complement the near-real time data from the ground-based networks with data from space missions (EO) currently available (MODIS, AVHRR, ASTER, HYPERION , COSMOSkyMed).
Prevention actions include development by DPC of an emergency plan, as well as the promotion of scientific activities with clearly defined objectives of specific interest for civil protection activities. In detail:
a) Since 1996 DPC has been promoting activities aimed at the definition of an Emergency Plan at Campi Flegrei. The latter and still active Working Group has been set up in October 2009, with the aim of defining pre-eruptive and eruptive scenarios at Campi Flegrei.
b) During the same long period DPC continuously promoted and supported the implementation of projects under the scientific coordination of INGV, with the aims of i) improving knowledge of the volcanic history and geology of the Campi Flegrei caldera; ii) improving basic understanding of the processes causing volcanic hazards; iii) setting up innovative methods for the evaluation and quantification of such hazards. The relevant results are implemented as part of the emergency management protocols within the civil protection system.
- To improve the mechanistic understanding of subsurface processes triggering volcanic unrest at Campi Flegrei, through petrologic reconstructions, geochemical studies, structural assessment of the caldera system, and physico-mathematical modelling and numerical simulation of underground magma dynamics.
- To identify reliable precursors associated with specific subsurface processes, by simulating the underground magma dynamics and the rock system response and establishing a mechanistic link between deep processes and signals observed at the surface.
- To improve the forecasting capacity of the outcome of volcanic unrest periods in the presence of scientific uncertainty, and the management of evolving volcanic crises from hazard assessment to decision-making.
Figure 1. The Serapis Temple in Pozzuoli (actually, a Roman marketplace), symbol of the town and of the bradyseism at Campi Flegrei. In the first half of last century the temple floor was below sea level. Holes produced on the temple columns by a red alga (lithothamnium) are used to trace back ground movements during last 2,000 years. Photo courtesy G. Orsi.
Figure 1 A. The bradyseism effects at the Serapis Temple in Pozzuoli. Photo courtesy DPC
Figure 2. The Monte Nuovo (about 130 m a.s.l.), a scoria cone produced during the last Campi Flegrei eruption in 1538. Photo courtesy G. Orsi.
Figure 2A. The Monte Nuovo, a cone produced during the last Campi Flegrei eruption in 1538. Photo courtesy DPC
Figure 3. The Solfatara crater at Campi Flegrei, site of intense degassing and abundant fumaroles. Photo courtesy G. Orsi.
Figure 3A. The Fumarolic activity in Solfatara area. Photo courtesy DPC
Figure 3B. The Solfatara crater. Photo courtesy DPC
Figure 4. The submerged Roman harbor “Portus Julius”. Photo courtesy DPC