Report on Campi Flegrei (Italy) — January 1986

Scientific Event Alert Network Bulletin, vol. 11, no. 1 (January 1986)
Managing Editor: Lindsay McClelland

Campi Flegrei (Italy) Gradual aseismic subsidence

Please cite this report as:

Global Volcanism Program, 1986. Report on Campi Flegrei (Italy). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 11:1. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198601-211010.

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Campi Flegrei

Italy

40.827°N, 14.139°E; summit elev. 458 m

All times are local (unless otherwise noted)


"Since January 1985, there has been no detectable seismic activity at Campi Flegrei [and] the ground has been subsiding at a mean rate of ~1 cm/month without any seismic activity (figure 15). The pattern of ground deformation during the crisis of 1982-84 was similar to that during 1970-72. The . . . latter crisis was accompanied by moderate seismic activity during the uplift phase. Gas monitoring of fumaroles in Solfatara Crater showed no significant changes in the past year.

Figure (see Caption) Figure 15. Changes in elevation (in cm) in the Campi Flegrei area recorded by a tide gauge at Pozzuoli, 1982-89. Inset shows vertical movement (in mm) at the point of maximum uplift on the Campi Flegrei levelling line, 1985-89.

"During the past year, people from Pozzuoli have slowly been moving back into the town. The new settlement on the NW side of the caldera has almost been completed, but it is not certain that all of the people evacuated from the town will move in. The fears of an impending eruption are already gone, and the interest of the media has vanished."

Geologic Background. Campi Flegrei is a large 13-km-wide caldera on the outskirts of Naples that contains numerous phreatic tuff rings and pyroclastic cones. The caldera margins are poorly defined, and on the south lie beneath the Gulf of Pozzuoli. Episodes of dramatic uplift and subsidence within the dominantly trachytic caldera have occurred since Roman times. The earliest known eruptive products are dated 47,000 yrs BP. The caldera formed following two large explosive eruptions, the massive Campanian ignimbrite about 36,000 BP, and the >40 cu km Neapolitan Yellow Tuff (NYT) about 15,000 BP. Following eruption of the NYT a large number of eruptions have taken place from widely scattered subaerial and submarine vents. Most activity occurred during three intervals: 15,000-9500, 8600-8200, and 4800-3800 BP. Two eruptions have occurred in historical time, one in 1158 at Solfatara and the other in 1538 that formed the Monte Nuovo cinder cone.

Information Contacts: G. Luongo and R. Scandone, Osservatorio Vesuviano (OV); F. Barberi, Univ di Pisa.