Page 400 - Caldera Volcanism Analysis, Modelling and Response

CHA P T E R 1 0

A New Uplift Episode at Campi Flegrei

Caldera (Southern Italy): Implications
for Unrest Interpretation and Eruption

Hazard Evaluation

Claudia Troise , Giuseppe De Natale, Folco Pingue, Umberto Tammaro,
Prospero De Martino, Francesco Obrizzo and Enzo Boschi

Contents

1. Introduction 376
2. Recent Ground Deformation Data at Campi Flegrei Caldera 379
3. Displacement Shapes and Maximum Vertical to Horizontal Ratios 384
4. Discussion and Conclusion 388
Acknowledgments 390
References 390

Abstract
Campi Flegrei caldera, which includes the highly urbanized city of Naples, is the most
dangerous volcanic area in the world as it represents a serious threat to around two
million people. During the last four decades it has experienced a huge uplift phase,
which reached about 3.5 m in 1985 when a subsidence phase started. Recent geodetic
data demonstrates that such a subsidence phase has terminated, and a new uplift
episode started in November 2004 has so far resulted in about 0.04 m of uplift (October
2006). Here we show that the present episode, which appears slower but longer
than previous small uplifts, sheds light both on the origin of small and large unrests,
and on the conditions to evolve toward large unrests. Our simple but robust method is
based on continuous GPS measurements and compares the ratio between maximum
horizontal to vertical displacements. Results show that such unrests are due to
overpressure in a deeper source of fluids of magmatic origin. When the resulting

Corresponding author. Tel.: +39-0816108314; Fax: +39-0816100811
E-mail address: troise@ov.ingv.it
Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Vesuviano, Via Diocleziano 328, 80124 Naples, Italy
Developments in Volcanology, Volume 10 r 2008 Elsevier B.V.
ISSN 1871-644X, DOI 10.1016/S1871-644X(07)00010-1 All rights reserved.
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