|Publications: SRL: Historical Seismologist|
In the pre-1900 time-window of earthquake catalogs, it is not unusual to come face-to-face with “fake” earthquakes erroneously listed among true ones. Such mistakes have been disclosed for many events, and their nature revealed and discussed in quite a number of papers in the last thirty years. Some discoveries of fake earthquakes originated from the revision of national catalogs (e.g., for France, Vogt 1979; for Italy, Guidoboni and Ferrari 1986 and Bellettati et al. 1993; for Germany, see a summary in Grünthal 2004), and others come from projects dealing with European-wide catalogs (e.g., Stucchi and Camassi 1997). As a consequence of these investigations, in some wellstudied European regions recent catalogs have been purged of most of these mistakes. A list of fake earthquakes is now available in some regional databases (France: BRGM-EDF-IRSN/ SisFrance 2010; Switzerland: Swiss Seismological Service 2002; Northern Europe: Grünthal et al. 2009), and a section devoted to fakes can be found in the European Archive of Historical Earthquake Data (AHEAD 2010).
Most fakes are in fact duplications deriving from historical records that supply different locations and dates of an individual event (e.g., Alexandre 1991), in many cases because dates are expressed according to different calendars in use in the same period in neighboring countries. Also, fake earthquake catalog records might be the result of a mistaken interpretation of rather obscure records on other natural phenomena, such as storms or landslides (e.g., Alexandre 1990; Albini et al. 1990; Albini and Vogt 1992; Alexandre 1993).
Among the most elusive catalog records to be unraveled as fakes are the ones originating from wrong locations of true earthquakes. Such misinterpretations of historical earthquake records might be found in 19th to early 20th century seismological literature, and from there they propagated, quite unobtrusively, into modern earthquake catalogs. To uncover these mistakes, one has but to start from the most recent catalogs and trace back the studies mentioned by the catalog compilers themselves, in order to retrieve the original records and be in a position to interpret them anew.
This approach was recently used in an ad hoc investigation (Albini et al. 2010) on the past centuries’ earthquakes in the Balkan Peninsula (Europe). At the base of this research was the awareness that the seismicity of the past centuries in the Balkan Peninsula is still far from having been adequately investigated (even today, the comprehensive reference catalog for the whole Balkan Peninsula is the one produced in the framework of the Balkan UNESCO project by Shebalin et al. in 1974). The investigation resulted in discovering that about 20 earthquakes still included in current parametric catalogs should be identified as fakes. Among them emerged the tangled case history of a mislocated earthquake. This case is presented in this paper as a paradigmatic one, to explain how the background information on an earthquake is retrieved and specifically to show how it came to light that a good-quality historical earthquake record had been twisted, wrongly interpreted, and eventually included in earthquake catalogs with an incorrect date and location.
In the most recent earthquake catalog for Romania, Oncescu et al. (1999) list an earthquake in the year 1276, with intensity 7 and Mw 6.0 (Figure 1). As their reference, they quote the catalog by Costantinescu and Marza (1980), who listed a 1276 earthquake that has the same epicentral coordinates and the same intensity (7) supplied by Oncescu et al. (1999). In turn, Constantinescu and Marza make reference to Shebalin et al. (1974), who also include a 1276 earthquake in their catalog. Differently from what is done for almost all events up to 1900, for this specific earthquake this catalog does not supply any parameters, and the information available to the catalog compilers is summarized as follows (Figure 1):
1276, in Arcesci, region of Craïova (Romania) fortifications and houses collapsed (MF)
“MF” is the code Shebalin et al. ( 1974) u sed t o r efer t o Montandon’s seismological compilation (1953). According to Montandon (Figure 1), the earthquake damaged “Arcesci” and “Slatina” in the Romanian region to the northeast of “Craïova, bassin de l’Olt (Valaquie).” The references mentioned by Montandon with respect to the 1276 earthquake (Figure 1) are:
Both Perrey and Mallet correctly reported the record supplied by von Hoff (1840) (Figure 1).
Having found out that von Hoff (1840) is the study at the root of the information passed into the catalogs, the last step was to retrieve the source he mentioned, a “Bar Hebraeus.”
Grighor Abu al-Faraj, aka Bar Hebraeus (born in Malatya, Turkey, in 1225 or 1226 and died in Marāgha, Iran, in 1286), was a scholar of wide interest and a prolific writer, as well as a bishop of the West Syrian Church (territories of Iran and Azerbaijan). In his Chronicon Syriacum, he wrote that the towns of “Arcastia” and “Cilath” in eastern Turkey had been affected by an earthquake “Ineunte anno 1587 feria quinta die tertio Tischrin” [“in the year 1587 on a Thursday the third day of the month of Tischrin”]. The original date was expressed in the calendar of the Greek Indictions1In historical chronology, indictions are conventional periods of 15 years, the opening date of which in the Greek (Constantinopolitan) Indictions began with 1 September 312. The Greek Indictions were used within the regions covered by the East Orthodox Church, such as in this case. and translated into “circa 1276” in the edition and translation from Syriac into Latin done by Bruns and Kirsch in 1789 (see “Bar Hebraeus” in the References). This most probably was the same edition of Bar Hebraeus used by von Hoff (see Figure 1, “lat. p. 577” meaning “Latin version on p. 577”).
Reading Figure 1 from bottom to top may help the reader to retrace how the fake record was created:
No hints could be found in any published study that the 1276 Romania earthquake might have been mislocated. However, a study by Guidoboni and Comastri (2005) that was carried out independently from this investigation and directly relying upon the same record from Bar Hebraeus’s Chronicon Syriacum further supports the evidence that the original historical record is about a true earthquake in eastern Turkey (Figure 2), dated 3 October 1275 according to our calendar.
The two earthquakes are in fact one and the same, or in other words the “1276 event in Romania” is the duplication born from the misinterpretation of a reliable and coeval record on an earthquake in eastern Turkey.
Though striking, the case of the 1276 event is not isolated. For instance, a March 1353 earthquake in “Romagna” (a region in northern Italy) was deleted from the Italian catalog (Postpischl 1985) because it had been inserted on the basis of the misreading of “Romània” that was used by the coeval chronicler to indicate the eastern Roman (or Byzantine) Empire (Bellettati et al. 1993; Guidoboni and Comastri 2005). The earthquake in fact happened in March 1354 and seriously affected the area of the Sea of Marmara (Guidoboni and Comastri 2005; Ambraseys 2009).
A more general lesson learned is that to avoid the persistence of wrongly interpreted historical earthquake records, and the resulting mislocation in time and space of well-documented historical earthquakes, catalogs of neighboring regions should be done by cross-checking the original sources and not simply merging the existing national catalogs. This is a trustworthy way to discover incorrectly cataloged earthquakes, because fake earthquakes do love to hide their true identity and come back into catalogs, again and again.
AHEAD (2010). Archive of Historical Earthquake Data; http://emidius.eu/AHEAD/main/index_fakes.php.
Albini, P., A. Bellani, and M. Stucchi (1990). Terremoti e frane nelle Alpi centrali. Atti del 7° Convegno Annuale del Gruppo Nazionale di Geofisica della Terra Solida I, 129–146. Roma: Esagrafica.
Albini, P., I. Cecic I, and R. Glavcheva (2010). Fake and overestimated earthquakes in the Balkans. 32nd European Seismological Commission General Assembly, Montpellier (France), 5–10 September 2010, abstract, p. 58.
Albini, P., a nd J. Vogt ( 1992). L andslide o r e arthquake? C ase h istories from historical sources. In Proceedings of the French-Italian Conference on Slope Stability in Seismic Areas, ed. E. Faccioli and A. Pecker. Nantes: Ouest Editions, Presses Académiques, 11–24.
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Alexandre, P. (1991). The Seismic Cataclysm of 29 March 1000: Genesis of a Mistake. Tectonophysics 193, 1–3, 45–52.
Alexandre, P. (1993). Les compilations séismologiques et le prétendu cataclysme provençal de 1227. Internal report. Observatoire Royal de Belgique, Rapport interne, 9 pp.
Ambraseys, N. (2009). Earthquakes in the Mediterranean and Middle East: A Multidisciplinary Study of Seismicity up to 1900. Cambridge, UK: Cambridge University Press, 968 pp.
Bar Hebraeus [Grighor Abu al-Faraj] (13th century). Chronicon Syriacum, ed. P. I. Bruns and G. G. Kirsch (1789). Vol. 1, Latin translation, 647 pp.+ Notes, LII pp; Vol. 2, Syriac text, 614 pp. Lipsiae: Apud A. F. Bohemium.
Bellettati, D., R. Camassi, and D. Molin (1993). Fake quakes in Italy through parametric catalogues and seismological compilations: Case histories and typologies. Terra Nova 5 (5), 488–495.
BRGM-EDF-IRSN/SisFrance (2010). Catalogue des faux séismes et séismes douteux; http://www.sisfrance.net/donnees_faux.asp.
Costantinescu, L., and V. I. Marza (1980). A computer-compiled and computer-oriented catalog of Romania’s earthquakes during a millennium (984–1979). Revue Roumanie de Geologie Geophysique et Geographie (Série Geophysique) 24, 171–191.
Grünthal, G. (2004). The History of Historical Earthquake Research in Germany. Annals of Geophysics 47 (2/3), 631–643.
Grünthal, G., R. Wahlström, and D. Stromeyer (2009). The unified catalogue of earthquakes in central, northern, and northwestern Europe (CENEC)—updated and expanded to the last millennium. Journal of Seismology; doi:10.1007/s10950-008-9144-9.
Guidoboni, E., and A. Comastri (2005). Catalogue of Earthquakes and Tsunamis in the Mediterranean Area from the 11th to the 15th Century. Bologna, Italy: INGV-SGA, 1,037 pp.
Guidoboni, E., and G. Ferrari (1986). The inexact catalogue: The study of more than 1700 earthquakes from the XI and the XX century in Italy. Terra Nova 1, 151–162.
Hoff, K. E. A. von (1840). Chronik der Erdbeben und Vulkan Ausbrüche. Gotha: Justus Perthes IV, 470 pp.
Mallet, R. (1853). First Report on the Facts of Earthquakes Phenomena, Catalogue of Recorded Earthquakes from 1606 B.C. to A.D. 1850. London: British Association for the Advancement of Science, 176 pp.
Milne, J. (1911). A Catalogue of Destructive Earthquakes A.D. 7 to A.D. 1899. London: British Association for the Advancement of Science, 92 pp.
Montandon, F. (1953). Les tremblements de terre destructeurs en Europe. Genéve, 195 pp.
Oncescu, M. C., V. I. Marza, M. Rizescu, and M. Popa (1999). The Romanian earthquake catalogue between 984–1997. In Contributions from the First International Workshop on Vrancea Earthquakes, Bucharest, Romania, November 1–4, 1997, ed. F. Wenzel and D. Lungu, 43–48. Dordrecht-London: Kluwer Academic Publishers. Catalog available at http://infp.infp.ro/catal.php.
Perrey, A. (1850). Mémoires sur les tremblements de terre ressentis dans la peninsule Turco-ellenique et en Syrie. Mémoires couronnées et mémoires des savant etrangers. Bruxelles: Academie Royale des Sciences, des Lettres et des Beaux Arts de Belgique, 23, 73 pp.
Postpischl, D. (1985). Catalogo dei terremoti italiani dall’anno 1000 al 1980. Bologna: Quaderni della Ricerca Scientifica 114 (2B), 239 pp.
Shebalin, N. V., V. Karnik, and D. Hadzievski, eds. (1974). Catalogue of Earthquakes of the Balkan Region. I, UNDP-UNESCO Survey of the Seismicity of the Balkan Region. Skopje, Macedonia: UNESCO, 600 pp.
Stucchi, M., and R. Camassi (1997). Building up a parametric earthquake catalogue in Europe: The historical background. In Historical and Prehistorical Earthquakes in the Caucasus, ed. D. Giardini and S. Balassanian, 357–374. Dordrecht: NATO ASI Series, 2 Environment, 28.
Swiss Seismological Service (2002). ECOS—Earthquake Catalog of Switzerland; List of fake earthquakes at http://histserver.ethz.ch/fukfakequery.htm.
Vogt, J. (1979). Problèmes de méthode. In Les tremblements de terre en France, 9–15. Orléans Cedex, France: Editions du BRGM.
1 In historical chronology, indictions are conventional periods of 15 years, the opening date of which in the Greek (Constantinopolitan) Indictions began with 1 September 312. The Greek Indictions were used within the regions covered by the East Orthodox Church, such as in this case.
Posted: 30 December 2010