Wednesday, March 10, 2010

The Yammouneh Fault

Of the five major faults which outcrop in Lebanon (e.g. Beydoun 1977, Walley 1988), the Yammouneh is the most continuous and clearly evident on satellite images (e.g. Ambraseys & Barazangi 1989). Evidence for its continuity has been described by Garfunkel et al. (1981). They used its morphological characteristics, largely established from topographic maps, to infer that the fault is an active transcurrent structure. The southern portion of the fault coincides with the eastern slopes of the uplifted Jabel Barouk structure, forming the western edge of the southern Bekaa valley. To the north of the town of Chtaura the fault lies within the high ground of Mount Lebanon. Here it is characterised by a series of enclosed karstic sedimentary basins or poljes (Garfunkel et al. 1981). The Yammouneh Fault emerges from the northern edge of the mountains along Wadi Chadra. Here it appears to offset the southern outcrop edge of the Homs Basalt by about 10km. A similar offset is recognised on the north side of the Basalt, in NW Syria, and the Yammouneh is inferred to be continuous with the Ghab Fault (Garfunkel et al. 1981), linking northwards to the East Anatolian Fault (e.g. Joffe & Garfunkel 1987, Hempton 1987).

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