AHEAD European Archive of Historical EArthquake DataEuropean Archive of Historical EArthquake Data

It was a bright cold day in April, and the clocks were striking thirteen.

As in the incipit of the novel “1984” by George Orwell, the story told in this book began when an earthquake struck on 6 April 1667, and severely affected a large area of the eastern coast of the Adriatic Sea.

This book provides an in-depth reconstruction of the consequences of this earthquake, made possible by introducing the readers to that context, distant in time and space, and then allowing them to observe the phenomenon through the eyes and words of the people who experienced it, or witnessed the aftermath of it, and took the initiative to share their emotions, experiences and observations.

“On the eve of the earthquake” (Chap. 1) has the scope of setting the scene for the reader by describing the geographical and historical scenario in which the earthquake happened, reviewing the existing studies and presenting how the research for the sources of information was approached. The main set of 114 documents, used throughout this book, was arranged in chronological order and is described in an ad hoc table at the end of the chapter. Each item is defined by its own date, place, type and author, and its archiving or cataloging position is fully referenced. A relevant quote of the retrieved material is supplied in its full text and original language in digital format in the Electronic Supplementary Material (http://extras.springer.com).

Who were the authors of the written reports? What was the motivations and perspectives that persuaded them to compose their accounts? The answers to these questions are discussed in the section devoted to “The Earthquake Observers” (Chap. 2). The mixed fortunes of these fifteen observers are recounted in some detail, with the purpose of pinpointing them and their accounts in time and space, in order to best extract the information useful in seismological terms. Special attention was devoted to how the news spread throughout Europe, as this provides a fundamental insight into the dependence of several published items on very few original sources, on which the interpretation of this earthquake had been quasiexclusively based so far.

After having determined the exact time when “The earth began to quake” (Chap. 3), an overview is proposed of the actual earthquake observations, which, prior to this study, were scattered, and very often hidden, in many different types of sources in eight languages, mostly Latin and Italian, but also the seventeenth-century Dalmatian dialect, Croatian, English, French, Dutch and German. The earthquake’s effects are presented place by place, in a geographical sequence from north to south, and in the context of the country they belonged to in the year 1667. Finally, the collected records are interpreted, and macroseismic intensities, according to the European Macroseismic Scale 98, are assigned at 37 locations.

For those who experienced and survived the “sudden accident” of the Great 1667 Earthquake, the epilogue was written by one of the protagonists of this book, Francesco Bobali. “Life won’t be the same ever again”.

The “Epilogue” of this book concludes that the scenario resulting from this research has substantially changed the seismological knowledge of this earthquake. Also, it is a heartfelt acknowledgment to these “earthquake observers” of the past, who made all this possible.

Within the module NA4: "A Distributed Archive of Historical Earthquake Data" (coordinator of the module Dr. M. Stucchi) of the EU-NERIES project, the "Macroseismic Database of the Southern Balkan area" was compiled on a joint effort of ITSAK (Ch. A. Papaioannou and A.S. Savvaidis), as module Partner, and the Geophysical Laboratory of the University of Thessaloniki (B.C. Papazachos, as principal researcher, and C.B. Papazachos) for the time period 1000-1999. The database is temporarily hosted by the INGV-MI.

The source of the data (macroseismic Intensity Data Points) are:

• for the historical (before 1900) earthquakes, the books of Papazachos and Papazachou (1989, 1997, 2003) and
• for the earthquakes of the instrumental era, the bulletins of the National Observatory, the books of Papazachos and Papazachou (1989, 1997, 2003) and individual studies.

This volume is published as Part III of the Catalogue of Earthquakes of the Balkan Region which was issued in April 1974 as a basic collection of main earthquake parameters. Realizing the importance of isoseismal maps for further studies, the participating countries we're invited, at the very beginning of the project activities in December 1970, to make every effort to collect or compile as many isoseismal maps as possible. The response was very encouraging and more than 50.0 isoseismal maps were collected, of which 454 were finally selected for printing.

Dr. N. V. Shebalin, UNESCO expert in cataloguing, acted as editor of this volume. He checked all maps and completed or recompiled some of them; he also generalized the shape of all isoseismals for further application in determining the intensity- attenuation curves and in calculating focal depths. The original isoseismals drawn by national experts are preserved, the generalized isoseismals of Dr. Shebalin being drawn by thin lines. The maps covering more than one country required comparison and combination of individual sections. Technical problems related to these Operations are described by Dr. Shebalin in his explanatory text to the Catalogue for the years 1901-1970 (Part I, pp. 22-23).

As can be seen in the Atlas, there is no uniformity in the way of drawing isoseismals; some authors prefer a very detailed shape respecting every observation point, others prefer some kind of generalization of the macroseismic field and emphasize its main features rather than local variations of intensity. There are certain good reasons behind both approaches related to the further use of isoseismal maps. The most valuable are the maps on which the individual intensity data are plotted; they prevail in the Atlas and everybody can interpolate the isoseismals according to need, opinion and other factors.

The maps are disposed in chronological order which is sometimes slightly disturbed for technical reasons; therefore a list of maps and corresponding pages follows the Foreword. The key of each map indicates the basic earthquake parameters, symbols used, authors and the scale. A large portion of the maps had to be redrawn and this work was carefully done by Mr. I. Todorov at the Project Office.

All originals were drawn on scale 1:1 million, however, for printing purposes, the size of all maps was reduced proportionally from 1:2 to 1:4 approximately. The lay-out of the maps and all technical printing problems were arranged by Mr. V. Andjelkovic.

The present set of maps represents a unique collection of basic seismological information and all those who contributed to its preparation and printing deserve appreciation for their devoted and efficient work.