Event B is one of six palaeoseismic events identified in the Tekieh trench system which intersects the Serghaya Fault in the southern Zebadani Valley of Syria. The event was recognized in a trench system excavated across and parallel to 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 B is represented by Wedge 5, one of the post-alluvium colluvial wedges exposed in Trench 1. Wedge 5 is a yellowish deposit consisting of large clasts with a white patina within a silty-sandy matrix. The deposit is interpreted as a fault-derived colluvial wedge deposited against a buried fault scarp following surface rupture. A charcoal sample recovered from Wedge 5 provided the principal chronological constraint for the event.
The event records a 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 C was not measured directly, approximately 4 m of left-lateral displacement is associated with the pair of earthquakes represented by Events B and C, implying an average displacement of roughly 2 m for each event.
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 B 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.
Event B is dated by stratigraphic relationships, buried-channel chronology, and radiocarbon ages. Gomez et al. (2003) interpreted two palaeoseismic events (Events B and C) between the filling of Channel C2 (1690–1400 BCE) and deposition of Wedge 5. Channel C2 is constrained by radiocarbon dating of its basal fill to 1690–1400 BCE ( 2σ), while charcoal recovered from Wedge 5 yielded an age of 170 BCE–20 CE. Consequently, Event B occurred between 1690 BCE and 20 CE ( 2σ) and after Event C.
- 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)
Figure 10
Trench log for the east wall of Trench 2. A sequence of three incised and filled channels is shown, with a northward sense of younging. Black discs denote the positions of samples for radiocarbon dating. The profile above the trench log depicts the hillslope channel morphology east of the fault zone. The relative positions of the channel mouth and the buried channels were mapped using a total station. Apparent offsets of the buried channels are shown.
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Gomez et al. (2003)
