Foreword

Giuseppe Luongo and Roberto Scandone Osservatorio Vesuviano, Napoli

Dipartimento di Geofisica e Vulcanologia, Universith di Napoli

The Greek colonists of Southern Italy (VIII century B.C. ) called "Campi Flegrei" (Phle- graean Fields) the region surrounding the Bay of Naples including Vesuvius, the present Campi Flegrei, and Ischia, because of its re- semblance with a region of Greece with the same name (Campi FlegreJ of Pallene). The meaning of the name is Burning Fields, and ac- tually the Greek colonists experienced vol- canic eruptions occurring on the Island of Ischia.

In the XVIII century, the English naturalist Lord Hamilton published a book called "Campi Flegrei", describing the volcanoes of Southern Italy. Nowadays, Campi Flegrei in- dicates a smaller region at the west of the city of Naples.

The present Campi Flegrei is a caldera that arouse the interest of researchers since the be- ginning of modern geology when Lyell made his observations on the movement of the ground in the roman ruins of Serapis in Pozzuoli.

In more recent times, the area has been the object of a renewed interest because of its un- rest with relevant ground uplift (320 cm of cu- mulative uplift between 1968 and 1984) and earthquakes in the periods 1970-1972, and 1982-1984. Such phenomena were viewed as possible precursors of an imminent eruption, because of the similarity of events with the precursors of the only historical eruption that occurred in the area at Monte Nuovo in 1538.

At the same time, two other calderas, Long Valley in California and Rabaul in Papua-New Guinea, were displaying similar signs of un-

rest. The three calderas are located in inhab- ited areas so that the assessment of volcanic risk became a primary issue for the volcanolo- gists involved in the surveillance. Different stages of preparedness were made at the three volcanoes because of the different density of inhabitants; more than 50,000 people were evacuated from the inner part of Campi Fle- grei which has more than 300,000 people liv- ing in areas at risk from an eruption.

At the end of 1984 and in 1985 the unrest decreased at the three calderas without any eruption, and left the researchers with the new problem of correctly forecasting the evolution of a volcanic crisis and of being able to make a correct guess on the behaviour of quiescent volcanoes when they exhibit signs of unrest.

No clear and simple answer is available to this question. Our belief is that a partial an- swer may come from a detailed knowledge of the structure and pattern of activity of the vol- cano under investigation. We thought that a special issue of the Journal of Volcanology and Geothermal Research could have been a good occasion to collect together the different re- searches that have been made on this area dur- ing the last years.

This volume contains 15 original papers de- voted to the understanding and modelling of the structure and dynamics of Campi Flegrei. As it will be evident from the reading of this volume, there is no universal consensus on the genesis, structure, and volcanic evolution of Campi Flegrei, as well as on the nature of the episodes of unrest. We do not regard this as a

0377-0273/91/$03.50 © 1991 Elsevier Science Publishers B.V. All rights reserved.

VIII

limit because the scientific debate always ben- efits the advancement of science. The promise to stimulate the scientific debate is the best contribution that we can make to celebrate the 150th anniversary of the Osservatorio Vesuvi- ano, founded in 1841 to study the volcanoes of the Neapolitan region.

We want to dedicate this issue to the many volcanologists that, during the last 150 years, have been at the Osservatorio Vesuviano won- dering on the nature of volcanic phenomena and building up an invaluable amount of knowledge.