Event F is the oldest palaeoseismic event identified in Tekieh Trench 1 which intersects the Serghaya Fault in the southern Zebadani Valley of Syria. The event was recognized in a trench excavated across a ~4–4.5 m-high fault scarp where Late Pleistocene lacustrine sediments on the upthrown eastern block are juxtaposed against Holocene alluvial deposits on the downthrown western block. Event F is represented by Wedge 1, the oldest colluvial wedge exposed in Trench 1. Unlike the younger wedges, Wedge 1 occurs within the older undifferentiated alluvium (unit a) rather than above it. The wedge consists of well-rounded pebbles and flat gravel derived from limestone and lacustrine sediments within a reddish-brown matrix. Its geometry indicates deposition against a fault-generated scarp.
The event records an early Holocene surface rupture on the Serghaya Fault. The fault at this location displays predominantly left-lateral strike-slip motion with a possibility of a smaller dip-slip component. Although displacement for Event F was not measured directly, Gomez et al. (2003:658) estimated an avarge displacment of "about 2 m per event," based on "chronological relationships between the colluvial wedges" of Trench 1 and the faulted and displaced channels in Trenches 2 and 3. Using Wells and Coppersmith (1994) slip-to-magnitude scaling relationships, Gomez et al. (2003) estimated that approximately 2 m of coseismic slip corresponds to an earthquake of about MW 7.0–7.2. Event F was therefore probably a large surface-rupturing earthquake of similar magnitude, although this estimate is inferred from average slip per event rather than from a direct displacement measurement for Wedge 1.
Event F is dated by stratigraphic bracketing and radiocarbon ages. It post-dates "Soil Organics" sample T1-107Nbk which was "buried by" Wedge 1 and dates to 5730–5320 BCE ( 2σ). It pre-dates a bulk sample from the upper part of the undifferentiated alluvium (unit a), which which produced an age of 4720–4270 BCE after Bayesian refinement. Gomez et al. (2003:674) dated Event F to between 5600 and 4400 BCE with a 2σ confidence level.
- Fig. 2 Tectonic Location
Map from Gomez et al. (2003)
Shaded relief image depicting the gross morphology of the Serghaya fault. Faults and the main anticlinal hinges are shown. Geographic features:
- ZV = Zebadani Valley
- H = Mt Hermon
- D = Damascus
- B = Baalbek
- A = Aarsal
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Gomez et al (2003)- Fig. 3 Geologic Location
Map from Gomez et al. (2003)
Geology of the southern Zebadani Valley (Syria). See Fig. 2 for location. Stereonet depicts fault planes and associated striations from faulted Late Pleistocene lake sediments. The dotted line depicts the catchment for the hillslope drainage at the trench site (white square). The white star denotes the excavation of the upper colluvial wedge described in Gomez et al# (2001). White discs denote small drainage deflections (values in metres), including the example shown in Fig. 4. Topographic contour interval = 50 m.
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Gomez et al (2003)- Fig. 5a Detailed Location
Map from Gomez et al. (2003)
Map of trench site. 1 m relative contours are based on mapping with a total station
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Gomez et al (2003)- Fig. 5c Extremely Detailed Location
Map from Gomez et al. (2003)
Enlarged map of the trench site depicting the positions of the present channel (C1) and the precise locations of the buried channels (C2 and C3). Solid black lines indicate where the buried channels were observed and dashed lines indicate where buried channels were inferred. The patterns are consistent with Fig. 5(a).
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Gomez et al (2003)- Fig. 12 3D Drawing of Trenches 1 and 2
from Gomez et al. (2003)
Schematic block diagram illustrating the 3-D relationships of the features exposed in the trenches. A stratigraphic tie between the filling deposit of Channel C2 with the down-slope equivalent of Wedge 4 can be observed.
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Gomez et al (2003)Figure 8
Trench log for the northern wall of Trench 1 (see Fig. 7), exposing colluvial wedges, undifferentiated alluvium and Late Pleistocene lake sediments. Calibrated radiocarbon ages are shown.
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Gomez et al. (2003)