Sismovalp – WP04 – Generic Alpine Valley Types
Caracterization of the geological history of our valley
QUESTIONNAIRE
Please fill the questionnaire inside this file. You can add lines wherever needed. The
questionnaire should be filled as precisely as possible, with all available data.
The questionnaire should then be sent to corinne.lacave@resonance.ch before the end of
year 2004.
1)
Name of the valley: Val Resia (Udine)
2)
Geography / General information:
Country: Italy
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General orientation of the valley: East-West
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Thickness of quaternary deposits (min to max): estimated from 5m to more than 20m
(boreholes), possibly (estimated) up to 50 m.
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Elevation (above sea level) of the valley surface (upstream to downstream):
Ca. 1400 m (base of the ridge of Monte Guarda, Italy-Slovenia border) – 310 m
(Resiutta village, at the end of the valley). Most of the valley between 700 and 400
m. The highest point above the valley is the top of Mount Canin (2571 m)
3)
General shape of the valley: V-type
Length and main width of the valley: ca. 20 km length, 1km on the average (0.5 to 1.5
km for the sedimentary part), 4 to 8 km width (N ridge to S ridge).
History:
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General geological evolution of the valley:
The Resia Valley is controlled by the “Val Resia line”, a tectonic structure deepening
to the South. It is a typical backthrust of the more important overthrust (characterized
by a marked neotectonic activity – Friuli 1976 event) of the southernmost sector of the
Friuli Julian Prealps. The basement rocks are formed in majority by Upper Triassic
dolomites. Only in correspondence of the overthrust evaporitic rocks (thickness about
few tens of meters) outcrop.
In the last million years the Alpine region has been subject to numerous glaciations,
alternated to relatively warm or mild periods. The morphologic evolution shows
erosive processes alternatively due to glacial and fluvial actions. For this reason today
we can see typical fluvial morphologies beside the characteristic aspects of the glacial
morphology. This aspect predominates mainly at the head of the valley, where we can
still notice examples of perfectly conserved glacial cirque: in locality Cjadinut (M.
Cadin) and also in the great upland plain of Foran dal Muss-Piano di Prevala, that
shows traces of most recent glaciers. At present there is a small residual glacier near
the top of the M.Canin and some other small snowfields, but located to the north,
outside the valley. Almost all the valley is characterized by a series of alluvial terraces
several tens of meters high.
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Presence of a lake in the past : May be;
Over-digging : yes ;
in the present: NO (give location)
approximate depth (m) : some meters
Presence of glaciers in the past: YES;
znumber:. ?? surface:... ?? thickness:.. ??
Sismovalp – WP04 – Generic Alpine Valley Types
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4)
Historical seismic activity: YES; max Intensity: ..VIII (in the valley, 1976)
max
magnitude:.6.4 (Friuli 1976), 5.7 (Bovec-Krn 1998), 6.9 (Idrija 1511) Location: about 10
km to the south for Friuli 1976, 20 km to the east for Bovec-Krn 1998, about 50 km
to the SE for the Idrija 1511
Type of source data :
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Boreholes? YES (Friz & Gatto, 1979)
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Ambient vibrations? NO (planned within Sismovalp)
Gravimetry? YES (measurements done within Sismovalp)
Seismic? YES
(type) seismic characterization of first 30 m (measurements done
within Sismovalp)
Others: station strong motion: STOL (Etna accelerograph/RAF network)
References:
http://www.dst.units.it/raf/Welcome.html
Sismovalp project
Friz, C. and Gatto, G., 1979. Rapporto tra ambiente geologico e rischio sismico in
Val di Resia (Friuli). Memorie Museo Tridentino Scienze Naturali, Vol. XXIII, Nuova
serie, fascicolo unico.
Vaia, F. and Zorzin, R., 1982. Fenomeni di tettonica recente in Val Resia (Prealpi
Giulie). Gortania – Atti Museo Friul. Storia Nat., Vol 3, 5-20.
5)
Human activity:
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Urbanised surface: less then 1400 inhabitants concentrated mainly in four small
villages (population density)
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Industrial activity: NO; type: -
6)
Geology:
6.1) Bedrock:
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Bedrock type (both sides): mainly dolomites, some limestones, few evaporites
Average slope (both sides):
40° - 50°
Outcrop of bedrock inside the valley: YES
6.2) Quaternary deposits (valley filling and lateral deposits):
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Description of the quaternary deposits constitutive materials:
- alluvial : gravels
- lacustrine : silt and clay
- torrential : pebbles, scree
- morainic : pebbles, sands and clays
- others : conglomerates
Sismovalp – WP04 – Generic Alpine Valley Types
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General dip direction of the deposits: gently from East to the West
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Artificial fills : NO
7)
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Mud flow channel: NO
Fan delta: NO
Lacustrine delta: NO
Marsh / peat bog : NO
Collapse zone : NO
Landslide, creeping : NO
Rockfall activity : YES mainly on the left side
Scree deposits on the sides : YES
Lateral water stream, torrent, secondary valley : YES ; type : about 7 small and a
medium secondary torrent are present on the south (left) flank of the valley
Others : Presence of some erratic rocks
Attached documents :
Geological map of the valley (with structural info): available on paper
Cross-sections
Remarks:
available on paper