Page 310 - Caldera Volcanism Analysis, Modelling and Response

CHA P T E R 7

Structural Development of Calderas: a

Synthesis from Analogue Experiments

Valerio Acocella

Contents

1. Introduction 286
2. Analogue Modelling 287
2.1. General features 287
2.2. Materials and scaling 288
3. Experimental Studies on Calderas 289
3.1. General features 289
3.2. Caldera collapse without regional stress field 291
3.3. Caldera collapse under a regional stress field 296
4. Discussion 299
4.1. Consistency of the experiments 299
4.2. Towards a consistent experimental model 301
5. Comparison to Nature: Guidelines 302
6. Towards a New Caldera Evolution Scheme 305
7. Conclusions 307
Acknowledgements 308
References 308

Abstract
A number of analogue models studying caldera architecture and development have
been recently performed under different conditions (apparatus, materials, scaling
parameters, stress conditions). An overview of the experiments reveals a consistent
scenario for caldera structure and development, regardless of imposed boundary
condition. In fact, a complete collapse can be summarised through four main
stages, proportional to the amount of subsidence, progressively characterised by a:
(1) downsag; (2) reverse ring fault; (3) peripheral downsag and (4) peripheral normal
ring fault. A brief comparison to natural cases shows that all these experimental

Corresponding author. Tel:. 0039-06-57338043; Fax: 0039-06-54888201
E-mail address: acocella@uniroma3.it
Dip. Scienze Geologiche Roma Tre, Roma, Italy
Developments in Volcanology, Volume 10 r 2008 Elsevier B.V.
ISSN 1871-644X, DOI 10.1016/S1871-644X(07)00007-1 All rights reserved.
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