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for by Rosaccio (1593) and by the two 17th century authors Benincasa (1653) and
De Gregorio (1645). These, not coeval, sources are quoted by Bonito (1691), and
also Baratta (1901) relied upon Bonito's sources for this event. After investigating a
set of coeval sources without finding any other record, ENEL (1985) concluded that
the event had to be considered very doubtful, and in any case its effects should not
have exceeded Io 6-7 MCS.
The 1513 event in the area of Biasca/Bellinzona (Switzerland, Ticino) represents
a paradigmatic case of a landslide erroneously interpreted as an earthquake. The
event was located by Postpischl (1985a) at Bellinzona, Io 9 MCS, dated 10 Febru-
ary 1513 on the basis of Mercalli (1883) who associated it with the records of an
earthquake which occurred on the same date in Alessandria. The Swiss catalogue
(Mayer-Rosa, 1988) located the event near Biasca, Io 8 MCS, dated 1512, following
Volger (1857), who gathered information from German sources, although he also
mentioned sources that dated the event 1513, too. The event is clearly described as
a landslide since the source closest to it: Paolo Giovio (1550-1552), who was used
also by Bonito (1691). Scheuchzer (1716) put this event in a section entitled “On
landslides” ; Bertrand (1757) considered it unlikely to be an earthquake, as well as
von Hoff (1840) and Perrey (1848). Coeval sources, such as Muralto (1492-1520),
Cavitelli (1588) and, mostly, a manuscript note by the notary Nicolino Rusca of
Bellinzona (Rusca, 1515) reported a complex event: the landslide - still clearly
visible today and known as “Buzza di Biasca” - dammed the Blenio River that
formed a lake near Malvaglia. In 1515 a breach took place in the dam and the
waters flooded the valley down to Bellinzona and Lago Maggiore. The date of the
landslide is accurately determined as 30 September 1513 by the already quoted note
by Nicolino Rusca excluding any association with earthquakes of February 1513.
Nicolino Rusca reported: “1513, die veneris, ultimo septembris ,
fuit maxime
ruyna lapidum” . In addition, a systematic research in a number of coeval published
chronicles of the main towns in the area (for Sondrio: Merlo, 16th cent.; for Mi-
lano: Morigia, 1592; for Como: Muralto, 1492-1520; for Bergamo: Foresti, 1520;
for Cremona: Cavitelli, 1588) did not provide any earthquake record in September
1513, while one of them (Muralto, 1492-1520) mentions the landslide: “Mons qui
est ultra Belinzonam Bregni Vallis scissus est” .
Finally minor, although interesting cases, are the events of 1555 (Val Seriana,
Io 6 MCS) and 1618 (Piuro, Io 5 MCS). Both have been proved to be landslides
(Albini et al., 1988); the last one captured the European interest, because the town
of Piuro was buried under the landslide. The false “Piuro” event was later located
by the early parametric catalogues about 30 km east of Piuro, near Chiuro, because
of a misinterpretation of the place-name.
...
2.5 Conclusion
Altogether, out of the 25 earthquakes with Io
8 MCS in Postpischl (1985a) 9
were proved as fake or very doubtful and only 8 survived with moderate to high
damaging capacity (Io
7 MCS). The largest event became the one of 1117; a
few earthquakes underwent further Io reduction in later studies. Table 1 summarises
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