Field reconnaissance in the epicentral area of the 1808 Pellice Valley earthquake

Field reconnaissance in the epicentral area of the 1808 Pellice Valley earthquake

11/07/2019 Perigeo 0
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looking for geological evidence of recent earthquakes…

Pellice Valley lies in the SW Piedmont region (N Italy), in a structurally complex area where the Alps-Apennines junction is located.

Instrumental microseismicty map of Northern Italy (source CSI Catalogue – INGV); the arrow marks Pellice Valley location.

Piedmont is a region where a low seismic release rate is domiant, except for the so-called Pinerolese seismic zone and for some historical events, including the damaging 1808 Pellice Valley seismic sequence (Mw max ca. 5.64 – CPTI15).

Macroseismic data for the 1808 Pellice Valley mainshock (Mw 5.64) – source: DBMI15 catalogue.

Gianfranco Fioraso, a collegue from IGG-CNR Turin, in the last few years has fully revised the historical documentation on this event and wrote a full-detail book on this issue.
His work has allowed to depict a new and updated picture of of this sequence, providing unpublished data so far.

We are collaborating with Gianfranco and his collegue, Andrea Irace, on the active tectonics of the Piedmont region (see e.g., Frigerio et al., 2017) and we recently had the opportunity to visit the Pellice Valley, during a full-day field trip (Leader: Gianfranco Fioraso).

Geomorphological observations, in the foothills area, where large alluvial fans develop and close to the Pellice Valley, point to some topographic anomalies, possibly related with active blind thrusting.

Damages and repairs are still visible on some buildings of Luserna Village: on the left, the uppermost part of the tower bell has been rebuilt soon after the earthquake; on the right, a tilted arcade in the dowtown area of the village (photos by Gianfranco Fioraso).

In the epicentral area of the 1808 sequence, damages due to the earthquakes are still visible in some historical buildings. More interestingly, Gianfranco has already compiled a map of the most important Earthquake-induced Environmental Effects (EEEs)!

Earthquake-induced Environmental Effects (EEEs) of the 1808 Val Pellice sepuence (courtesy of Gianfranco Fioraso).

Temperatures were incredibly hot that day but we didn’t avoid hard field work! A recent flooding has exposed some new outcrops along the riverbank and…here we are! Beautiful soft sediment deformations affecting a glaciolacustrine sequence. Much older than our latest historical event, but still promising for paleoseismology.

Nicely preserved soft sediment deformations in a lacustrine sequence. Promising!

Stay tuned and more NEWS will come from Pellice Valley!

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