Vesuvius, Campi Flegrei, and Campanian Volcanism

Vesuvius, Campi Flegrei, and Campanian Volcanism communicates the state-of-the-art scientific knowledge on past and active volcanism in an area characterized by elevated risk due to high-density population. Eruptions, lahars and poisonous gas clouds have killed many thousands of people over recorded history, but volcanoes have given people some of the most fertile soil known in agriculture. The research presented in this book is useful for policymakers and researchers from these and other countries who are looking for risk assessment and volcanic evolution models they can apply to similar situations around the world.

Naples and its surrounding area, in particular, the area situated between Vesuvius and the Campi Flegrei volcanic area has a population in excess of 4 million people. The volcanic areas that have similarly large populations in proximity to dormant, but hazardous volcanoes, i.e., Indonesia and Central America can also benefit from this work.

• Covers the fundamental science of volcanoes, including new developments in the last decade relating to the use of crystals and melt inclusions to model the nature and evolution of volatiles
• Includes the latest research on volcanism in Southern Italy that is presented as a case study for active and inactive volcanoes across the globe
• Presents research that is applicable around the world, for people, scientists and policymakers living on, or near, active volcanoes

• Language: English
• Publisher: Elsevier Science
• Release date: Oct 11, 2019
• ISBN: 9780128175187

Book preview

Vesuvius, Campi Flegrei, and Campanian Volcanism

Editors

Benedetto De Vivo

Harvey E. Belkin

Giuseppe Rolandi

Table of Contents

Cover image

Title page

Copyright

Contributors

Acknowledgments

1. Introduction to Vesuvius, Campi Flegrei, and Campanian Volcanism

2. The contributions and influence of two Americans, Henry S. Washington and Frank A. Perret, to the study of Italian volcanism with emphasis on volcanoes in the Naples area

Henry Stephens Washington

Publications before and including 1906

Publications from 1906 to 1912

Publications after joining the Geophysical Laboratory, Carnegie Institution of Washington

Significance to Italian geology and petrology

Stories and anecdotes

Frank Alvord Perret

3. Kinematics of the Tyrrhenian-Apennine system and implications for the origin of the Campanian magmatism

Introduction

Geological setting

Evolution of the upper plate

Reconstruction of the subducted lower plate

Geometric evolution of the Ligurian-Ionian slab

Conclusions and implication on the Campanian magmatism

4. Lithosphere structural model of the Campania Plain

Introduction

Regional lithospheric models

Crustal structure of the Campania Plain

Conclusions

5. Campania volcanoes: petrology, geochemistry, and geodynamic significance

Introduction

Structural setting of volcanism in the Italian peninsula

A volcanological overview of the Campania Province

Petrology and geochemistry of the Campania volcanoes

Petrogenesis of Campania magmas

Geodynamic implications

Conclusions

6. Tracing magma evolution at Vesuvius volcano using melt inclusions: a review

Geological background

Magma evolution at Somma–Vesuvius volcano

Melt inclusions

Conclusions

7. Magmatism of the Phlegrean Volcanic Fields as revealed by melt inclusions

Introduction

Geological outlines of the Phlegrean Volcanic District

Description of melt and fluid inclusions found in the Phlegrean Volcanic District magmas

Insights about Phlegrean Volcanic District using melt inclusions

Discussion on melt inclusion data

Concluding summary

8. The 39 ka Campanian Ignimbrite eruption: new data on source area in the Campanian Plain

Introduction

Geostructural and geophysical outlines of Campanian Plain

Materials and methods

Landscape changes resulting from the areal distribution of 39 ka CI units and 15 ka NYT in the Campanian Plain

Volcanological setting of the Campanian Plain

Stratigraphic features of Campanian Ignimbrite unit-1 and vertical welding patterns in the Giugliano area

Transects of CI unit-1 in the N-CVZ

Relationships between physical properties and welding intensity for Campanian Ignimbrite unit-1

Discussion

9. Effect of paleomorphology on facies distribution of the Campania Ignimbrite in the northern Campania Plain, southern Italy

Introduction

Study area

Methods

Results

Discussion

Conclusive remarks

10. Petrogenesis of the Campanian Ignimbrites: a review

Introduction

Summary of Campanian tectonic, thermophysical, and geochemical properties

Campanian Volcanic Zone computational petrology

Concluding remarks

11. The Neapolitan Yellow Tuff eruption as the source of the Campi Flegrei caldera

Introduction

Separate sources for the Campanian Ignimbrite and Neapolitan Yellow Tuff

The Neapolitan Yellow Tuff caldera

Distribution and alteration of the Neapolitan Yellow Tuff

Caldera resurgence

Onshore geomorphology of Campi Flegrei

Postcaldera volcanic activity

Discussion

Conclusions

12. Space-time evolution of an active volcanic field in an extentional region: the example of the Campania margin (eastern Tyrrhenian Sea)

Introduction

Tectonics

Volcanism

Link between extensional faulting and volcanism

Space-time evolution of tectonic and volcanic systems

13. Petrologic experimental data on Vesuvius and Campi Flegrei magmatism: a review

Introduction

Phase equilibrium studies and applications

Volatile studies

14. Hydrothermal versus magmatic: geochemical views and clues into the unrest dilemma at Campi Flegrei

Introduction

The origin of the Campi Flegrei caldera hydrothermal system

Fluid geochemistry of the actively degassing area: Solfatara and Pisciarelli fumarole data and interpretations

Discussion

Conclusions and perspectives

15. Ground movement (bradyseism) in the Campi Flegrei volcanic area: a review

Introduction

Bradyseism at Campi Flegrei

Models for ground movements at Campi Flegrei

Thermodynamic model for ground movements at Campi Flegrei

Conclusions

16. The holocene marine record of unrest, volcanism, and hydrothermal activity of Campi Flegrei and Somma–Vesuvius

Introduction

Geological setting

Data and methods

Volcanic and hydrothermal features off the Naples Bay

Conclusion

17. Volcanological risk associated with Vesuvius and Campi Flegrei

Introduction

The eruptive history of Somma–Vesuvius

Flow hazard at vesuvius: The Red Zone of the emergency plan of Italian Department of Civil Protection

Suggestions for some criteria for the definition of Red Zone at Somma–Vesuvius

Campi Flegrei

Are we moving toward a third postcaldera volcanic period at Campi Flegrei?

Implications for hazard at Campi Flegrei

Concluding comments on Somma–Vesuvius and Campi Flegrei red zones

Index

Copyright

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Front Cover: the image La Grande Eruzione del Vesuvio del 1767 - The great 1767 Vesuvius eruption is of the artist Adriana Pignatelli Mangoni

Contributors

Harvey E. Belkin,     Retired, U.S. Geological Survey, Reston, VA, United States

Robert J. Bodnar,     Fluids Research Laboratory, Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States

Mauro Caccavale,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Claudia Cannatelli

Department of Geology, FCFM, University of Chile, Santiago, Chile

Andean Geothermal Center of Excellence (CEGA), University of Chile, Santiago, Chile

Michael R. Carroll,     Università di Camerino- Scuola di Scienze e Tecnologie, Sezione Geologia, Camerino, Italy

Marta Corradino,     Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Palermo, Italy

Maria Rosaria Costanzo,     Department of Earth Sciences, Environment and Resources, University of Naples Federico II, Italy

Giuseppe De Natale,     Istituto Nazionale di Geofisica e Vulcanologia, sezione di Napoli «Osservatorio Vesuviano», Napoli, Italy

Benedetto De Vivo

Pegaso On Line University, Naples, Italy

Adjunct Professor, Dept of Geosciences, Virginia Polytechnic Institute & State University (Virginia Tech), Blacksburg, VA, United States

Nanjing University, Nanjing, China

Hubei Polytechnic University, Huangshi, China

Massimo Di Lascio,     Consultant, Self-employed Geologist, Battipaglia (Salerno), Naples, Italy

Rosario Esposito,     University of California, Department of Earth, Planet, and Space Sciences, Los Angeles, CA, United States

Giuseppe Esposito,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Alessandro Fedele,     INGV—Osservatorio Vesuviano, Naples, Italy

Sarah Jane Fowler,     School of Earth Sciences, University of Bristol, Bristol, United Kingdom

Tom Gidwitz,     South Dartmouth, MA, United States

Christopher R.J. Kilburn,     University College London, London, United Kingdom

Annamaria Lima,     Dipartimento di Scienze della Terra, delle Risorse e dell’Ambiente, Universitá di Napoli Federico II, Naples, Italy

Chiara Macchiavelli,     Group of Dynamics of the Lithosphere, Institute of Earth Sciences Jaume Almera, Structure and Dynamics of the Earth, Barcelona, Spain

Fabio Matano,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Alfonsa Milia,     ISMAR, CNR, Napoli, Italy

Flavia Molisso,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Roberto Moretti

Université de Paris, Institut de Physique du Globe de Paris, CNRS UMR 7154, Paris, France

Observatoire Volcanologique et Sismologique de Guadeloupe, Institut de Physique du Globe de Paris, Gourbeyre, France

Concettina Nunziata,     Department of Earth Sciences, Environment and Resources, University of Naples Federico II, Italy

Giuliano Francesco Panza

Emeritus Honorary professor China Earthquake Administration (CEA), Beijing, China

Honorary professor Beijing University of Civil Engineering and Architecture (BUCEA), Beijing, China

Accademia Nazionale dei Lincei & Accademia Nazionale dei XL, Rome, Italy

Salvatore Passaro,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Angelo Peccerillo,     Retired from Department of Earth Sciences, University of Perugia, Perugia, Italy

Giulia Penza,     University of Camerino, School of Science and Technology—Geology Division, Camerino, MC, Italy

Fabrizio Pepe,     Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Palermo, Italy

Pietro Paolo Pierantoni,     University of Camerino, School of Science and Technology—Geology Division, Camerino, MC, Italy

Giuseppe Rolandi,     Retired, University Napoli Federico II, Napoli, Italy

Roberto Rolandi,     Dipartimento Scienze della Terra, Ambiente e Risorse, Università di Napoli-Federico II, Naples, Italy

Daniela Ruberti,     Department of Engineering, University of Campania L. Vanvitelli, Aversa (Caserta), Italy

Marco Sacchi,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Antonio Schettino,     University of Camerino, School of Science and Technology—Geology Division, Camerino, MC, Italy

Renato Somma,     INGV—Osservatorio Vesuviano, Naples, Italy

Frank J. Spera,     Department of Earth Science and Earth Research Institute, University of California, Santa Barbara, CA, United States

Volkhard Spiess,     Faculty of Geosciences, University of Bremen, Bremen, Germany

Paola Stabile,     Università di Camerino- Scuola di Scienze e Tecnologie, Sezione Geologia, Camerino, Italy

Lena Steinmann,     Faculty of Geosciences, University of Bremen, Bremen, Germany

Stella Tamburrino,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Maurizio M. Torrente,     DST, Università del Sannio, Benevento, Italy

Claudia Troise,     Istituto Nazionale di Geofisica e Vulcanologia, sezione di Napoli «Osservatorio Vesuviano», Napoli, Italy

Eugenio Turco,     University of Camerino, School of Science and Technology—Geology Division, Camerino, MC, Italy

Mattia Vallefuoco,     Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche (CNR), Sezione di Napoli, Napoli, Italy

Guido Ventura,     Istituto Nazionale di Geofisica e Vulcanologia, INGV, Roma, Italy

Marco Vigliotti,     Department of Engineering, University of Campania L. Vanvitelli, Aversa (Caserta), Italy

Acknowledgments

We acknowledge the support of Elsevier B.V. through the process of planning, writing, reviewing, and the production of Vesuvius, Campi Flegrei, and Campanian Volcanism. Behind the Elsevier banner is a staff of extremely competent, hardworking people, without whom the production of this volume would have been far more difficult and of lesser quality. Omer Mukthar Moosa, Mark Rogers, Sheela Bernardine B. Josy, and Amy Shapiro are gratefully thanked. We especially thank Hilary Carr, whose excellent editorship has led and instructed us to the successful completion of this volume. We also thank Adriana Pignatelli Mangoni, Naples, Italy, for the use of her gouache La Grande Eruzione del Vesuvio nel 1767 that appears on the volume's cover. Lastly, we thank all the chapter authors for their contributions and the many peer reviewers for their suggestions and corrections.

Benedetto De Vivo

Harvey E. Belkin

Giuseppe Rolandi

1

Introduction to Vesuvius, Campi Flegrei, and Campanian Volcanism

Benedetto De Vivo ¹ , ² , ³ , ⁴ , Harvey E. Belkin ⁵ , and Giuseppe Rolandi ⁶       ¹Pegaso On Line University, Naples, Italy      ²Adjunct Professor, Dept of Geosciences, Virginia Polytechnic Institute & State University (Virginia Tech), Blacksburg, VA, United States      ³Nanjing University, Nanjing, China      ⁴Hubei Polytechnic University, Huangshi, China      ⁵ Retired, U.S. Geological Survey, Reston, VA, United States      ⁶ Retired, University Napoli Federico II, Napoli, Italy

Abstract

From Pliny the Younger’s letters to Tacitus describing the 79 CE Vesuvius eruption to numerous scientific investigations in the 21st century, the volcanically active area around Naples, Italy, has been the subject of much research. More than 3 million people live in this potentially hazardous region, thus the ongoing research is critically needed to accurately delineate hazardous zones and to assess and communicate the risk to the local population. This introductory chapter sets the scene and rationale for the next 16 chapters that summarize the current state of the art regarding the history, geology, petrology, and geophysics of the volcanic area of Naples, Italy, that includes Mt. Somma–Vesuvius, Campi Flegrei, the Island of Ischia, and the Ignimbrites volcanism of the Campanian Plain.

Keywords

Campi Flegrei; Campania Plain; Ignimbrites; Mt Somma; Vesuvius; Volcanic risk

In August of CE 79, Vesuvius was erupting (although, recent archeological research suggests the month was October). In two letters to the Roman historian Tacitus, Pliny the Younger describes the events. The first letter describes the journey of his uncle, Pliny the Elder, during which he perished. Pliny the Elder had received a letter from Rectina, the wife of Tascus, asking to be rescued, but due to the ongoing eruption, the rescue boat could not reach the shore near her home and instead Pliny the Elder sailed to Stabiae to meet Pomponianus where they both died. The second letter by Pliny the Younger describes his observations of the eruption from Misenum, a town in the Pozzuoli Gulf, across the Bay of Naples. These letters are probably the very first detailed description of a volcanic eruption. It is interesting also to note that Pliny the Younger never mentions the towns of Ercolano and Pompeii, so their existence remained unknown until the late 16th century, when they were discovered covered by Mt. Somma pyroclastics.

For the next two millennia, scientists, clergy, travelers, politicians, ambassadors, and others have written thousands of papers, books, and other documents on the volcanoes and volcanism in the Naples region that includes Mt. Somma–Vesuvius, Campi Flegrei (CF), the Island of Ischia, and related rocks. Thus, it would be reasonable to assume that all the questions have been asked, and all the answers have been given regarding the science of the Neapolitan volcanic region. Unfortunately, the reality is just the opposite!

The geology and geophysics of the Neapolitan volcanic region are very complex—the tectonics, the petrology, the lithospheric structure beneath the volcanic systems, and many other geological and geophysical aspects. After nearly 2000 years of research, the following three questions cannot be answered with any confidence: will there be another volcanic eruption in the Naples area, and if so, where, and when?

Answers to these questions do not have just academic interest, as there are more than three million people living in the Neapolitan volcanic region.

In the Repubblica Italiana, the Department of Civil Protection is given the very important and difficult task of preparing volcanic risk maps, zoning, and other aspects related to the potential of a volcanic eruption. The risk maps, zoning, etc., must be continuously updated as new geologic information and research becomes available. For one thing is absolutely certain that during a volcanic eruption, the lava, pyroclastic flow, ash cloud, etc., will not obey any political boundaries or preconceived scenarios.

With this book on the volcanism of the Neapolitan region (Vesuvius, CF, and ignimbrites in the Campanian plain), we hope that the scientific points of views of different authors are not interpreted as certainties. Some of the chapters highlight ongoing controversial subjects related to the volcanism of the Neapolitan volcanic region, such as the source of the 39 ka Campanian Ignimbrite (CI), the significance of the bradyseism in CF, the nature of the Neapolitan Yellow Tuff (NYT) eruption, and the delineation of volcanic hazard zones for civil protection. Such controversy is a very healthy part of scientific progress as it forces all the involved scientists to reexamine their data, assumptions, and hypotheses. The literature is filled with rejected or modified theories as new data were collected and examined. What we consider important is that whatever the real scenario, in the short and long term, for Vesuvius, CF, and ignimbrites in the Campanian plain, the results are obtained only if there is a nondogmatic approach, which favors an impartial and balanced evaluation of peer-reviewed research. This, unfortunately, has often not been the case in Italy in recent years, especially due to an overly tight and unhealthy link between politics and various research groups. These links do not benefit science or the society that supports it. This dogmatic approach is especially egregious if decisions regarding the public safety and security are made using biased or poorly evaluated scientific research. We hope that these chapters will enable researchers to study the controversial issues of the Campanian Plain volcanism for the benefit of science and people living around the metropolitan area of Naples.

Sixteen chapters in this volume have been selected to give the reader an idea of the current state of the art regarding the various aspects of geology and geophysics related to the Neapolitan volcanic region. A short summary of each chapter by the different authors is given below:

Chapter 2 : Belkin and Gidwitz (The contributions and influence of two Americans, Henry S. Washington and Frank A. Perret, to the study of Italian volcanism with emphasis on volcanoes in the Naples area) report the work, significance, and influence, one century ago, of two American researchers, Henry Stephens Washington and Frank Alvord Perret, in Italian volcanism with emphasis on Neapolitan volcanoes. Both Washington and Perret made significant contributions to the geology, petrology, and volcanology of Italy, in general, but in particular to the Vesuvius, CF (Phlegraean Fields), and the Island of Ischia. Both, from the East Coast of the United States, published classical works on Italian volcanoes, the Roman Comagmatic Region and the Vesuvius Eruption of 1906, published by the Carnegie Institution of Washington.

Chapter 3 : Pierantoni et al. (Kinematics of the Tyrrhenian-Apennine system and implications for the origin of the Campanian magmatism) make a reconstruction of the geodynamic evolution of the Italian peninsula to understand the processes, which allowed the formation of the magma following the geometry of the Ligurian–Ionian slab. In their reconstruction, the Campanian Plain is located above a singular asthenospheric window, created by the Ionian slab detachment, which determines, during the Upper Pleistocene, an elastic rebound of the Apulian continental lithosphere. The consequent mantle upwelling gives rise to the huge amount of magma that characterizes the Campanian Plain.

Chapter 4 : Nunziata et al. (Lithosphere structural model of the Campania Plain) discuss the lithosphere structural model of the Campania Plain. According the authors, a mantle wedge (VS of about 4.2   km/s), 50   km thick, is found at depths shallower than 30   km, on the top of the westward subducting Apenninic lithosphere, overlying two faster layers (VS of about 4.4   km/s) up to about 300   km of depth. This is compatible with buried huge amounts (more than 1.5   km) of calc-alkaline andesitic and basaltic lavas and with the geochemical and petrological findings that subduction-related magmas, with broadly trachybasaltic compositions, were parental to all the volcanic suites in Campania. A main feature in the upper crust is the low VS layer (5% velocity reduction) that starts at about 14–15   km of depth and reaches the Moho. The low-velocity crustal layer seems to be a regional feature as it has been found below Roccamonfina in the north and CF, Bay of Naples, and Mt. Vesuvius in the south. The widespread presence of such layer, with the percentage of velocity reduction peaking below the CF District and Mt. Vesuvius, seems to be consistent with the presence of an extended reservoir, fed from a deep source located in the upper mantle, from which the pockets of magma may rise to shallower depths.

Chapter 5 : Peccerillo (Campania volcanoes: petrology, geochemistry and geodynamic significance) discuss the petrology, geochemistry, and geodynamics of the Campania Magmatic Province—including Somma–Vesuvius, CF, and Ischia and Procida islands—which is petrologically and geochemically distinct from the Roman province, but with close similarities with Stromboli volcano, in eastern Aeolian arc, suggesting that the Campania volcanoes do not represent the southern extension of the Roman province, but rather the northern end of the Aeolian arc. Both the Campania and Stromboli parental magmas were generated from a mantle source that was affected by metasomatic modifications by fluids coming from the subducting Ionian oceanic slab and associated sediments. The ocean island basalt–type component of the eastern Aeolian and Campania volcanoes was provided by mantle inflow from the foreland. Asthenospheric mantle migration took place through a slab window formed by along-strike tear-off of the Ionian-subducting lithosphere and was favored by suctioning by the slab sinking and rollback toward the southeast.

Chapter 6 : Cannatelli (Tracing magma evolution at Vesuvius volcano using melt inclusions: a review) traces evolution of Somma–Vesuvius, making a review of melt inclusion (MI) studies. In the last few decades, the volcanic complex has served as a natural open laboratory, where scientists have applied different analytical techniques (geophysical and geochemical) to unravel the nature and evolution of magmas, the location and structure of magma storage, the effect of volatile on determining frequency, and the style of eruptions. Cannatelli presents the major findings and existing knowledge about a geochemical tool that, in the last few decades, has been used to understand volcanic behavior and nature: MIs. In particular, the author focuses on the use of MIs as a tracer for magma geochemical composition and evolution at Somma–Vesuvius and recompiles all the available MI data previously published in the literature.

Chapter 7 : Esposito (Magmatism of the Phlegrean Volcanic Fields as revealed by melt inclusions), to answer questions on the evolution and source of the CF magmatism, uses as investigative tool MIs. Esposito compares the MI data from the literature related to CF, Procida, and Ischia and he highlights three main points based on this comparison. The first is that only a few MI show quasiprimitive composition, and these can be compared to investigate the magma sources below the three different localities of the Phlegrean Volcanic District (PVD), highlighting that the same magma source could be present below the three localities of the PVD at different times. The second point is that some of the more evolved MIs show divergence from the bulk rock trend, indicating a natural reheating before eruptions, driven either by hotter magma recharging or by crystal settling. The third point is that many MI in the literature are showed as bubble-bearing, not taking into account the volatile contents of bubbles, thus indicating that more research is needed to corroborate or discredit advanced interpretations of preeruptive volatile contents based on MIs.

Chapter 8 : Rolandi et al. (The 39 ka Campanian Ignimbrite eruption: New data on source area in the Campanian Plain ), based on new drillings through the Campanian Plain, report that the CI is composed of two 39 ka depositional units, clearly distinguished by their areal distribution and welding characteristics: CI Unit-1 at the base, covered in some areas by CI Unit-2. The CI Unit-1 is the most extensive gray tuff deposit showing an unusual degree of welding within the southwestern sector—Giugliano area—of the Campania Plain, which is never found in the ignimbritic deposits in other areas of the Plain. The absence of a caldera in the Giugliano area indicates that the CI source is associated with one or more regional tectonic structures. Probably, this source area was extended to the south, but it was not related to the Campi Flegrei caldera (CFc) as assumed by other authors. From the Giugliano area, the coignimbrite expanding gas increased strongly, following a long runout over the flat topography of the Campanian Plain and by impacting, in the north and east, the Apennine and Roccamonfina reliefs.

Chapter 9 : Ruberti et al. (Effects of the palaeomorphology on facies distribution of the Campanian Ignimbrite in the northern Campania Plain, southern Italy) discuss the effects of palaeomorphology on facies distribution of the CI (39 ka), one of the most explosive eruptions in the last 200 ka in Europe. The pyroclastic deposits associated to this event show different lithofacies from the vent to the medial distal part reflecting changes in style of deposition and/or palaeoenvironmental setting. Based on about 1000 well log stratigraphies and previous studies, a qualitative restoration was made of the pre-39 ka CI eruption palaeomorphology of the Campania Plain, where four main paleogeographic domains are recognized, conditioning the medial/distal distribution of the lithofacies across the plain and their volcanoclastic characteristics.

Chapter 10 : Fowler (Petrogenesis of the Campanian Ignimbrites: a review) reviews intensive research results over the past two centuries based on tectonic, geochemical, and thermophysical database within the Campanian Volcanic Zone, particularly with regard to the voluminous 39.28   ±   0.11 ka CI. New observations on pre- and post-CI deposits provide a basis for identifying long-term petrogenetic patterns. The review summarizing different aspects of Campanian Volcanic Zone research highlights major advances, providing a foundation on which to test hypotheses and construct quantitatively constrained predictions. The importance of fractional crystallization and open-system mechanisms including magma mixing and assimilation during magma evolution is emphasized.

Chapter 11 : Rolandi et al. (The Neapolitan Yellow Tuff eruption as the source of the Campi Flegrei caldera) present an analysis of the CF, formed inside a 12   ×   16   km caldera system as a result of the 15 ka NYT eruption, which produced about 50   km³ of trachytic magma. Caldera collapse developed within a regional tectonic extensional regime, where local faults mirror regional fault trends. The result was complex caldera architecture, indicated by multiple features attributable to the interaction between trapdoor and downsag geometries. The authors present geological and volcanological constraints to propose an evolutionary sequence model whereby the NYT is an isolated volcanic structure that formed only in response to a single 15 ka eruption, in contrast to some previous theories.

Chapter 12 : Milia and Torrente (Space-time evolution of an active volcanic field in an extended region: the example of the Campania Margin, eastern Tyrrhenian Sea) discuss results of their study investigating offshore and onshore areas of the Campania Margin in terms of stratigraphy, tectonics, and volcanism at a regional scale, not focusing their research works at explaining the relationships between tectonic and volcanism on a single volcano or eruption. The authors documented and reconstructed the 3D geometry of several buried volcanoes and volcanoclastic deposits and recognized a complex late Quaternary tectonic evolution of the region. These results suggest a strict genetic link between rifting and volcanic activity in terms of space-time evolution and that high volumes of magma rose to the surface through regional faults.

Chapter 13 : Stabile and Carroll (Petrologic experimental data on Vesuvius and Campi Flegrei magmatism: a review) discuss experimental studies of compositions relevant to magmatism at Vesuvius and CF, as they provide constraints on the pressure, temperature, and magmatic volatile activities prevailing during various phases of eruption. Such information helps to define pressures (depths) of origin for some well-studied eruptions and differentiation trends that link magma compositions potentially related by crystal-liquid differentiation processes. Likewise, studies of volatile solubility in the relatively alkali-rich melt composition characteristic of Vesuvius and CF magmatism can provide valuable constraints for interpreting the composition of MIs in phenocrysts of many eruptive products. The authors discuss how these experimental data can help to explain pressures of MI entrapment, the possible importance of hydrosaline brines in some magmas, and degassing processes or CO2 fluxing experienced by melt compositions preserved in MIs.

Chapter 14 : Moretti et al. (Hydrothermal vs. Magmatic: Geochemical views and clues into the unrest dilemma at Campi Flegrei), based on the geochemical data recorded at CFc in the last 35ka, review the two main approaches appearing in the literature, yielding diametrically opposite conclusions when comparing the 1982–84 and ongoing (post-2000) CFc unrest episodes. The authors show that inert gases help to evaluate the geochemical signature of the deep upwelling gas, not compatible with a magma migrating to shallow depths in recent times. After the exhaustion of the volatile content of the shallow magma emplaced in 1982–84, only the deep-sourced (8   km) magmatic gas feeds and heats the present-day hydrothermal system. The authors establish that the nature of the 1982–84 unrest was magmatic, due to the emplacement of a shallow (3–4   km deep) magma, interfering with the normal degassing dynamics from the deep (8   km) magmatic reservoir of regional size. On the contrary, the post-2005 unrest is unlikely magmatic and most likely hydrothermal. The discussed scenarios confirm in all cases, and independently of the type of unrest, the strong role played by the CO2-rich gas release of deep provenance.

Chapter 15 : Cannatelli et al. (Ground movement (bradyseism) in the Campi Flegrei volcanic area: a review), after illustrating the CF volcanic evolution, discuss the different theories and interpretation of the ground movements (bradyseism) phenomenon periodically occurring in one of the highest risk volcanic areas on Earth and one of the most densely populated volcanically active areas in the world. The active caldera of CF, located just west of the city of Naples, has been known since Roman times for its hydrothermal activity, intense volcanism, and slow, vertical ground movements, called bradyseism. In their contributions, the authors provide a detailed review of the several models proposed in the past 40 years to explain ground movements at CF. Although several authors propose that the driving mechanism for the accelerated ground uplift at CF can be attributed to an emplacement of magma at shallow depth, no scientific (petrological, geochemical, or geophysical) evidence seems to support this hypothesis. The authors suggest, in contrast with other models, that a hydrothermal model without magmatic recharge paints a better picture of the bradyseism phenomenon, as it better links scientific data available in the literature with the magmatic-hydrothermal processes at CF.

Chapter 16 : Sacchi et al. (The Holocene marine record of unrest, volcanism and hydrothermal activity of Campi Flegrei and Somma–Vesuvius) document the marine record of a spectrum of volcanic, hydrothermal, and sedimentary features that characterize the latest Pleistocene–Holocene evolution of the Naples Bay offshore CF and Somma–Vesuvius. The authors results are based on the integrated analysis of high-resolution marine digital terrain models derived from swath bathymetry surveys and high-resolution reflection seismic profiles calibrated with marine gravity core data. Between the Somma–Vesuvius and Pozzuoli Bay, seismic profiles calibrated with gravity core data revealed the occurrence of a hummocky seafloor region, known as Banco della Montagna (i.e., the Montagna Bank). This volcanic bank was shaped by the dragging and rising up of volcanoclastic diapirs (mostly unconsolidated pumice) as a consequence of pore fluid overpressure at depth and associated active fluid venting at the seafloor.

Chapter 17 : De Vivo and Rolandi (Hazard assessment on Vesuvius and Campi Flegrei active volcanic areas: A critical review and alternative views) suggest that the eruptive history of Somma–Vesuvius and CF gives reasonable reasons to expect eruptions in the future, and they critically discuss the effectiveness of the present delimitation of the Red Zones of both volcanic active areas carried out by the Italian Department of Civil Protection and present their alternative views. The authors believe that both the risk assessment models expounded by DCP do not use the best scientific data for estimating the areas and levels of risk that could be associated with the next probable worst-case scenario eruptions, both at Somma–Vesuvius and CF.

2

The contributions and influence of two Americans, Henry S. Washington and Frank A. Perret, to the study of Italian volcanism with emphasis on volcanoes in the Naples area

Harvey E. Belkin ¹ , and Tom Gidwitz ²       ¹ Retired, U.S. Geological Survey, Reston, VA, United States      ² South Dartmouth, MA, United States

Abstract

A century ago, two Americans, Henry Stephens Washington and Frank Alvord Perret, made significant contributions to the geology, petrology, and volcanology of Italy, in particular to those volcanoes in the Naples area, Vesuvius, Campi Flegrei (Phlegraean Fields), and the Island of Ischia. Both were from the eastern United States, both were born in 1867, and both studied physics as undergraduates. However, each man followed a different scientific path and approach in his volcanological studies. Washington was classically trained and more interested in rock chemistry, mineralogy, and petrogenesis. Perret was a gifted inventor, worked in Edison's laboratory, established his own company, and was a keen observer of volcanic phenomena and processes; today he would be called a physical volcanologist Each man published classic works on Italian volcanoes, The Roman Comagmatic Region (Washington, 1906) and The Vesuvius Eruption of 1906 (Perret, 1924); both were published by the Carnegie Institution of Washington. However, both men had cosmopolitan tastes for other volcanoes, and they traveled widely and made significant contributions to the knowledge of other volcanic areas.

The following two sections present, albeit briefly, their work, significance, and influence to Italian volcanism with emphasis on those volcanoes in the Naples area.

Keywords

Campi Flegrei; Frank A. Perret; Henry S. Washington; Ischia; Italy; Naples; Vesuvius; Volcanology

Henry Stephens Washington

Introduction

Henry Stephens Washington, the son of George and Eleanor P. (Stephens) Washington, was born in Newark, New Jersey, on January 15, 1867. His family was well-to-do, related to that of George Washington, and he grew up on a homestead in Locust, New Jersey, a few kilometers from the Atlantic shore. At age 12, he had his own chemistry laboratory, and at age 15, he entered Yale College, where he received his A.B. degree with special honors in physics and natural science. Washington continued at Yale and received an A.M. in 1888. As a graduate assistant in physics, he studied mineralogy and petrography. An early published work involved a crystallographical and optical study of copper minerals under the direction of Prof. E. S. Dana in collaboration with W.F. Hillebrand of the US Geological Survey (USGS) (Hillebrand and Washington, 1888). After Yale, he attended the American School of Classical Studies at Athens, Greece, and participated in various archeological excavations with his brother Charles M. Washington. In 1891, Washington enrolled at Universität Leipzig with Professors F. Zirkel and C.H. Credner for petrographic and geologic studies leading to a PhD with highest honors in 1893. For his PhD he studied a group of volcanoes in what is now eastern Turkey (Washington, 1894a). In 1895, he returned to Yale to study rock and mineral chemical analysis under the guidance of Professor Louis V. Pirsson. Using Pirsson's techniques as a basis, Washington equipped his own laboratory at his boyhood home in Locust, New Jersey. Now in an independent position, he could collect, petrographically describe, and analyze any rock he collected; some of the first rocks he analyzed were those he collected in Italy (Merwin, 1952).

From the 1890s until his death in 1934, Washington produced a prodigious volume of scientific work encompassing geology, petrology, mineralogy, chemistry, and archeology (e.g., Keyes, 1934; Merwin, 1952; Milton, 1991). He was interested in archeology throughout his life and continued to publish on its various aspects especially related to mineralogy and rock chemistry (e.g., Waldstein and Washington, 1891; Washington, 1894b, 1898, 1921, 1922).

For more details concerning his life, the reader should consult stories, memorials, and obituaries by Keyes (1934), Fenner (1934), Lewes (1935), Barth (1936), Spencer (1936), Merwin (1952), Gibson (1983), and Milton (1991).

Milton (1991) describes three phases in Washington's life, centered on his wife running off with an Englishman, and a failed investment in Brazilian diamonds (cf. Gibson, 1983). Thus, in light of this reversal of fortune, Washington became a consulting mining geologist with a New York City office from 1906 to 1912. During this interval, his basic research was curtailed. In 1912, he joined the Geophysical Laboratory, Carnegie Institution of Washington. The general structure of this chapter section will use these three periods to describe his research in the form of commentary on his relevant publications.

This chapter section is concerned with Washington's contributions related to the petrology and mineralogy of Italy, with particular emphasis on the volcanic region around Naples, Italy, including Mt. Somma–Vesuvius, Campi Flegrei (Phlegraean Fields), and the Island of Ischia. Washington was principally a petrologist interested in rock chemistry and mineralogy, but he also included detailed geographic and geologic descriptions of the research regions to place his geochemical, mineralogical, and petrological data in the proper context.

After the publication of The Roman Comagmatic Region in 1906, Washington did not study, in detail, the volcanoes around Naples, but studied many other Italian volcanic regions. These studies will be briefly summarized to show the significance of Washington's research to the petrological and mineralogical knowledge of Italian geology. Some publications cited were translated or abstracted into Italian; these are not discussed.

Publications before and including 1906

On some Ischian trachytes, 1896

In the Fall of 1894, Washington visited the volcanic Island of Ischia, about 30   km southwest of Naples in the Gulf of Naples, southern Italy, to collect representative specimens for study. During petrographic examination of thin sections, Washington (1896a) observed sheaf-like bundles of feldspar crystals from samples collected from Mt. Rotaro that he found interesting enough to publish a short descriptive paper on them before a more detailed text (see Some Analyses of Italian Volcanic Rocks I section). He spent much text discussing the origin of these spherulites and compares their shape and texture with many similar references in the literature.

Italian Petrological Sketches, 1896–97

In 1896–1897, the Journal of Geology published five long papers ( Washington, 1896b,c; 1897a,b,c) on four Italian volcanic areas plus a summary and conclusions: 1—The Bolsena Region, 2—The Viterbo Region, 3—The Bracciano, Cerveteri, and Tolfa Regions, 4—The Rocca Monfina Region (note that name is now Roccamonfina in today's literature), and 5—Summary and Conclusion.

In Sketch 1, Washington describes his trip to Italy in 1894, visiting the Italian volcanic areas and collecting representative samples for petrographic examination and chemical analysis. As he explains:

The number and easy accessibility of its volcanoes render Italy an enticing field for the geologist. The peculiar characters of their eruptive rocks, which are rich in potash, and in which leucite is a most common mineral, render them of special interest to the petrologist. It would seem, however, judging from a quite extensive survey of the literature, that the country has been rather neglected in recent years by petrologists; since, except for a comparatively small number of modern papers describing limited districts, we must turn for many of our descriptions to the writers of more than a quarter of a century ago. Few attempts also have been made to correlate the facts in our possession for the purpose of determining the general petrological characters of the Italian province.

The organization in each of the four Regional Sketches is as follows: (1) Bibliography—Washington reviews all the references known to him, but only discusses the more recent papers relevant to each region, (2) Topography—A detailed description, including latitude and longitude, is given, (3) Petrography—An extensive discussion of all the rock types Washington identified in his collection and reference to those described by others, but not collected by him. Thin sections were prepared and detailed descriptions of the mineralogy are given, and (4) Chemical Composition—Tables are presented that give rock analyses from the literature that Washington had deemed worthy, plus a few he analyzed personally. In the last Sketch, Washington concludes that what he has studied, from Bolsena to the Campanian volcanoes, constitutes a petrographical province characterized chemically by low to moderate silica and high K2O and petrographically by the abundance of leucite in many rock types. His discussion of the Campanian volcanoes is limited to the recognition that Vesuvius is different from both Ischia and Campi Flegrei, and the latter have abundant trachyte, in contrast to most of the northern volcanoes he examined.

Some analyses of Italian volcanic rocks I and II, 1899–1900

In two papers, Washington (1899, 1900) publishes the results of his rock analyses and mineralogical studies on rocks collected and described in his Italian Petrological Sketches. He states his reasons:

During the past two years I have made a number of analyses of Italian volcanic rocks, with the intention of incorporating them in a general article on the subject. As, however, other work has come up which will delay this indefinitely, it has been decided to publish them. Isolated analyses of rocks, without discussion of their relations to those of other connected types, are of little use. But they may prove of service to others investigating this region, and personally I would like to clear out this pigeon-hole.

His pigeonhole includes analyses of trachytes from the Phlegraean Fields (Campi Flegrei) and the Island of Ischia (Part I); ciminite (latite) from Mt. Cimino, Viterbo, mica-trachyte from Mt. Catini, Tuscany, andesite from Radicofani, Tuscany, and leucitite from Capo di Bove, Alban Hills (Part II). In spite of his desire to just present the data without discussion, he does give detailed discussions and comparisons with some of his analyses and mineralogy. Furthermore, he discusses some of his older data in light of more analytical experience and knowledge and repudiates a former analysis, explaining the chemical details. The analysis I. Leucitite from Capo di Bove, Washington analyst (Washington, 1900, p. 53), gives K2O   =   8.97wt%, ∼2wt% higher than an 1869 analysis by Bunsen from the same locality shown for comparison. Washington's data are correct and reflect the modal abundance of leucite [K(AlSi2)O6] in the rock. Spencer (1936) and my petrology professor, S.A. Morse, related that some colleagues during Washington's time playfully suggested that tobacco ash accounted for the high percentages of potash in his rock analyses; a cigar was his constant companion, and he handed one to whomever he met (see Fig. 2.3 below).

Cross, Iddings, Pirsson, and Washington, 1902

Early on in Washington's study of igneous rocks, he recognized the need for classification and systemization based on accurate rock chemistry, and so did Whitman Cross (USGS), Joseph P. Iddings (USGS), and Louis V. Pirsson (Yale), and together they produced the Cross, Iddings, Pirsson, and Washington (CIPW) norm classification (Cross et al., 1902) that has lasted for more than 100 years, albeit with some modifications. In the 1906 The Roman Comagmatic Region text, Washington presents CIPW norms for all his rock chemical analyses.

The Roman Comagmatic Region, 1906

Washington (1906) published The Roman Comagmatic Region (Fig. 2.1) as an extensive summary, to date, of his fieldwork, petrography, and chemical analyses of volcanics from Lake Bolsena north of Rome, extending southeast to Vesuvius, Ischia Island, and Campi Flegrei at Naples. The Carnegie Institution of Washington, which published the volume, partially sponsored these studies. Here, he not only describes the petrography and chemistry of his extensive collections but also proposes that these volcanoes have a common origin and defines the volcanic region as a comagmatic region.

Any reader of this volume should be forewarned that Washington uses rock names proposed by Cross et al. (1902) based on chemistry and divided into class, order, rang, and subrang; however, Washington also gives the old name, e.g., subrang phlegrose = trachyte, which will be more familiar to the modern reader.

He divides the comagmatic region into seven districts: Vulsinian—the volcanic complex around Lake Bolsena, Ciminian—volcanoes near Viterbo, Sabatinian—the volcanic complex around Lake Bracciano, Latian—the Colli Albani complex, Hernican—volcanics in the Saco River area, Auruncan—the Roccamonfina complex, and the Campanian district. The Campanian district comprised three quite distinct centers of activity, Mt. Somma–Vesuvius, Campi Flegrei (Phlegraean Fields), and the Island of Ischia. Washington recognized that the cessation of volcanic activity from north of Rome to Naples shifted southerly, mostly gleaned from historical references before radiometric dating. The last recorded eruption of Ischia was in CE 1302, the last eruption in Campi Flegrei was Monte Nuovo in CE 1538, and recent Vesuvius activity started in CE 1631 and continued to erupt with an average 7-year repose period.

Figure 2.1 Front cover of The Roman Comagmatic Region (Washington, 1906).

About 70% of the text is devoted to petrography where he describes in detail, each of his 38 subrang Roman comagmatic region rock types. Each description includes Megascopic characters, Microscopic characters, Chemical composition, Mode, Occurrence, and Name. At the end of each rock type discussion, there is a summary of the hand specimen character, microscopy, mineralogy, and what are considered type specimens. In the Mode section, the norm is given and compared with the measured mode. The norm, a calculated theoretical mineralogy based on the chemical composition, had only been recently developed (Cross et al., 1902). Washington also gave analyses from other authors from the sample or similar locality. He often commented on their quality and would give a detailed explanation on why some other analyst's results differ from his determinations.

After the extensive petrographic and chemical descriptions, Washington defines the Roman comagmatic region as follows: silica (SiO2) ranges from 45 to 62wt%, but most vary from 56 to 47wt%, alumina (Al2O3) is generally high with a narrow range only from 17 to 20wt%, lime (CaO) is high with a considerable range, and soda (Na2O) tends to be low and varies from 1.0 to 7.2 with most from 1.5 to 3.5wt%. The most distinguishing chemical characteristic of this comagmatic province is the high potash (K2O) content that ranges from 3.7 to 11.3wt% with the majority only from 6.4 to 9.6wt%—it is indeed a potassic province. A detailed discussion of the Normative Characters follows, where Washington notes that normative quartz is rare, and most of the rocks are nepheline or leucite normative. He also notes that in the Campanian District, the three magmatic centers have distinct rock chemistry with those of the Island of Ischia more closely related to Campi Flegrei than to Vesuvius.

A very instructive section follows, where Washington compares the Roman comagmatic region with others such as the Bohemian, Eifel, Laacher See, and especially the Highwood District in Central Montana, extensively studied by his colleague, L.V. Pirsson.

The two concluding sections are on the formation of leucite and the distribution of barium. Leucite phenocrysts are a nearly universal mineralogical characteristic of the Roman comagmatic region rocks, and where it appears in the norm, it also is in the mode, in contrast to nepheline. Washington gives a set of conditions seemingly required for leucite formation; low silica content (<56wt%), a SiO2/K2O ratio lower than 13, and K2O/Na2O   >   1. Washington compares the distribution of barium in the Roman comagmatic region with other areas and notes that its concentration increases with increasing K2O, and analyses suggest that it is in potassium feldspars, not leucite. He also notes that ZrO2 has a predilection for sodic rocks and Cr2O3 for magnesia-rich rocks.

Publications from 1906 to 1912

In the summer and autumn of 1905, Washington visited the volcanic districts of Catalonia, Sardinia, Pantelleria, and Linosa, with the aid of a grant from the Carnegie Institution of Washington (incorporated by United States Congress in 1902; now also called the Carnegie Institution for Science). During this period, his work as a consulting mining geologist limited his basic research.

Washington published studies on two islands near Sicily, Pantelleria and Linosa (Washington, 1908, 1909; Washington and Wright, 1908, 1910). The publications with F.E. Wright marked the start of his collaboration with members of the Geophysical Laboratory of the Carnegie Institute of Washington, recently founded on December 12, 1905. Other studies related to the southern Mediterranean regions concerned Catalan volcanoes (Washington, 1907a) and the titaniferous basalts of the western Mediterranean (Washington, 1907b). He also continued his research on leucite [K(AlSi2)O6] that he started in The Roman Comagmatic Region 1906 with two papers (Washington, 1907c,d).

He maintained his collaboration with Cross, Iddings, and Pirsson, and they published articles on igneous rock textures (Cross et al., 1906) and modifications to their quantitative rock classification (Cross et al., 1912).

Publications after joining the Geophysical Laboratory, Carnegie Institution of Washington

Publications 1912 to 1919

The Geophysical Laboratory was established in 1905 as part of the Carnegie Institution of Washington to investigate the processes that control the composition and structure of the Earth, including development of the underlying physics and chemistry and to create the experimental tools required for the many experimental tasks. Arthur L. Day was the first director of the Geophysical Laboratory in 1906 and had come from the Division of Physical and Chemical Research of the USGS. Henry S. Washington was hired as a petrologist (Fig. 2.2) in 1912 and remained there until his death in 1934, except for a period during World War I when he was scientific attaché at the American Embassy in Rome. Presumably, he moved his analytical laboratory from Locust, New Jersey to the new Geophysical Laboratory campus on Upton Street, Washington, D.C. (Fig. 2.3).

Figure 2.2 H.S. Washington's business card that notes his new address.

Figure 2.3 Henry S. Washington, c.1922, in the Geophysical Laboratory, preparing to analyze Hawaiian rocks. 

Photo from