Reconstructing 4000 years of mass movement and tsunami history in a deep peri-Alpine lake (Lake Geneva, France-Switzerland)

The study of mass movements in lake sediments provides insights into past natural hazards at historic and prehistoric timescales. Sediments from the deep basin of Lake Geneva reveal a succession of six large-scale (volumes of 22 × 106 to 250 × 106 m3) mass-transport deposits, associated with five mass-movement events within 2600 years (4000 cal bp to 563 ad). The mass-transport deposits result from: (i) lateral slope failures (mass-transport deposit B at 3895 ± 225 cal bp and mass-transport deposits A and C at 3683 ± 128 cal bp); and (ii) Rhône delta collapses (mass-transport deposits D to G dated at 2650 ± 150 cal bp, 2185 ± 85 cal bp, 1920 ± 120 cal bp and 563 ad, respectively). Mass-transport deposits A and C were most probably triggered by an earthquake, whereas the Rhône delta collapses were likely to be due to sediment overload with a rockfall as the external trigger (mass-transport deposit G, the Tauredunum event in 563 ad known from historical records), an earthquake (mass-transport deposit E) or unknown external triggers (mass-transport deposits D and F). Independent of their origin and trigger mechanisms, numerical simulations show that all of these recorded mass-transport deposits are large enough to have generated at least metre-scale tsunamis during mass movement initiation. Since the Tauredunum event in 563 ad, two small-scale (volumes of 1 to 2 × 106 m3) mass-transport deposits (H and I) are present in the seismic record, both of which are associated with small lateral slope failures. Mass-transport deposits H and I might be related to earthquakes in Lausanne/Geneva (possibly) 1322 ad and Aigle 1584 ad, respectively. The sedimentary record of the deep basin of Lake Geneva, in combination with the historical record, show that during the past 3695 years, at least six tsunamis were generated by mass movements, indicating that the tsunami hazard in the Lake Geneva region should not be neglected, although such events are not frequent with a recurrence time of 0·0016 yr−1.

Agat‘angełos

The Encyclopedia of the Medieval Chronicle brings together the latest research in chronicle studies from a variety of disciplines and scholarly traditions. Chronicles are the history books written and read in educated circles throughout Europe and the Middle East in the Middle Ages. For the modern reader, they are important as sources for the history they tell, but equally they open windows on the preoccupations and self-perceptions of those who tell it. Interest in chronicles has grown steadily in recent decades, and the foundation of a Medieval Chronicle Society in 1999 is indicative of this. Indeed, in many ways the Encyclopedia has been inspired by the emergence of this Society as a focus of the interdisciplinary chronicle community. The Encyclopedia fills an important gap especially for historians, art historians and literary scholars. It is the first reference work on medieval chronicles to attempt this kind of coverage of works from Europe, North Africa and the Middle East over a period of twelve centuries. 2564 entries and 65 illustrations describe individual anonymous chronicles or the historical oeuvre of particular chroniclers, covering the widest possible selection of works written in Latin, English, French, Spanish, German, Dutch, Norse, Irish, Hebrew, Arabic, Greek, Syriac, Church Slavonic and other languages. Leading articles give overviews of genres and historiographical traditions, and thematic entries cover particular features of medieval chronicles and such general issues as authorship and patronage, as well as questions of art history. Textual transmission is emphasized, and a comprehensive manuscript index makes a useful contribution to the codicology of chronicles.