San Demetrio ne’ Vestini fault (AQ) · Paleoseismological investigations across the San Demetrio...

Blumetti A.M., Di Manna P., Vittori E., Comerci V., and Guerrieri L.

Holocene earthquakes along the

San Demetrio ne’ Vestini fault (AQ)

33 convegno Gruppo Nazionale Geofisica della Terra Solida, Bologna, 25 - 27 novembre 2014

Tectonic framework


Quaternary faulting in the San Demetrio area


Pucci et al., 2014

Bosi e Bertini, 1970 Bertini e Bosi, 1993

Giaccio et al., 2012

The San Demetrio fault


A’

B’

C’

C

B

A

0 250 500 m

San Demetrio historic center

N

The San Demetrio fault scarp


Geophysical investigations


General view of the trench


Fault zone shown in the NE trench wall


General view and detail of the fault zone shown in the SW trench wall



Stratigraphic log of the NE trench wall


Location of samples taken in the NE trench wall

Datings


Sample Radiocarbon Age (BP)

δ13C (‰) Calibrated ages (Range 2 )

SD61 4070 ± 45 -25.6 ± 0.5 2760 BC (81.3%) 2470 BC

SD62 18944 ± 80 -20.8 ± 0.8 21100 BC (95.4%) 20550 BC

SD64 7858 ± 60 -38.3 ± 0.7 7030 BC (95.4%) 6570 BC

SD63 6359 ± 60 -29.3 ± 0.6 5470 BC (95.4%) 5220 BC

SD65 4717 ± 45 -38.4 ± 0.5 3640 BC (53.8%) 3480 BC

SD43 14960 ± 65 -31.3 ± 0.5 16430 BC (95.4%) 16010 BC

SD50 38344 ± 400 -31.4 ± 0.7 41100 BC (95.4%) 39900 BC


Stratigraphy before earthquake 1

Earthquake 1, age comprised between

16430-16010 BC and 7030-6570 BC

Deposition of colluvial wedges 10

and 9 after earthquake 1

Earthquake 2

age younger than 7030-6570 BC


Deposition of colluvial wedge 8

after earthquake 2

Deposition of levels 7, 6 and 5

Earthquake 3, age comprised between 5470-5220 BC

and 3640-3480 BC, and deposition of colluvial wedge 4

Deposition of level 3 and base of 2 and earthquake 4,

age younger than 2760-2470 BC


Detail of the stratigraphic log

of the NE trench wall

Conclusions


Paleoseismological investigations across the San Demetrio ne’ Vestini fault have

confirmed its capability, in fact:

• based on the stratigraphic setting exposed in the trench wall, i.e: two

faulted colluvial wedges, at least 4 surface faulting events with individual

offsets from a few centimetres to several tens of centimetres have been

identified;

•based on radiocarbon age of layers involved in the deformation, it is possible

to refer 3 surface faulting events to the Holocene, respectively to an age

younger than 7030-6570 BC, comprised between 5470-5220 BC and 3640-

3480 BC and younger than 2760-2470 BC;

• an older surface faulting event, related to an earthquake with much larger

magnitude than the other ones because associated to a large gravity graben,

occurred between 16430-16010 BC and 7030–6570 BC

San Demetrio ne’ Vestini fault (AQ) · Paleoseismological investigations across the San Demetrio...

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