Event A is the youngest palaeoseismic event 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 A is represented by Wedge 6, the youngest colluvial wedge recognized in Trench 1. The wedge consists of centimetre-sized pebbles and gravel derived from limestone and lacustrine sediments. Much of the original deposit has been truncated by modern cultivation, and a plastic cigarette wrapper recovered from approximately 25 cm below the surface indicates recent disturbance. Despite this disturbance, the remnant of Wedge 6 is interpreted as the colluvial deposit associated with the most recent surface-rupturing earthquake on the Serghaya Fault.

The event records a surface rupture on the Serghaya Fault apparently involving oblique slip, displaying predominantly left-lateral strike-slip motion with a smaller dip-slip component. Small hillslope drainages displaced across the fault indicate approximately 1.9–2.5 m of left-lateral offset, and Gomez et al. (2003:672) interpreted the most recent event as having produced approximately 2–2.5 m of predominantly strike-slip displacement. Slickensides and striations preserved in faulted Late Pleistocene lake sediments indicate a strike-slip to dip-slip ratio of approximately 4:1 to 5:1. If a similar slip ratio is applied to Event A, 2–2.5 m of left-lateral displacement would imply a vertical component of roughly 0.4–0.6 m. This estimate is derived from kinematic indicators preserved in the Late Pleistocene lake sediments rather than from direct measurements of Event A itself.

Using Wells and Coppersmith (1994) strike-slip-to-magnitude scaling relationships, approximately 2-2.5 m of coseismic strike-slip corresponds to an earthquake of about M_W 7.0–7.4. Historical accounts of the 25 November 1759 CE Baalbek Quake earthquake suggest a fault break on the Serghaya Fault (Daeron et al., 2005), a magnitude of about M_W 7.4 (Ambraseys and Barazangi, 1989) and over 100 km of surface rupture (Daeron et al., 2005).

Event A is dated by a charcoal radiocarbon sample ( T1-03N) which was found in silty sand below Wedge 6 and dated to after 1650 CE ( 2σ). Thus, it is highly likely that Event A represents a manifestation of the 25 November 1759 CE Baalbek Quake.

• Fig. 2 Tectonic Location      
  Fig. 2
  
  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

  
  click on image to open in a new tab
  
  Gomez et al (2003)
  Map from Gomez et al. (2003)
• Fig. 3 Geologic Location      
  Fig. 3
  
  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.
  
  click on image to open in a new tab
  
  Gomez et al (2003)
  Map from Gomez et al. (2003)
• Fig. 5a Detailed Location      
  Fig. 5a
  
  Map of trench site. 1 m relative contours are based on mapping with a total station
  
  click on image to open in a new tab
  
  Gomez et al (2003)
  Map from Gomez et al. (2003)
• Fig. 5c Extremely Detailed Location
  Fig. 5c
  
  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)
  Map from Gomez et al. (2003)
• Fig. 12 3D Drawing of Trenches 1 and 2
  Fig. 12
  
  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.
  
  click on image to open in a new tab
  
  Gomez et al (2003)
  from 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)