J. Fleury, J. Chorowicz & J. Somma write: In their recent paper Butler et al. 1997 discussed the active Dead Sea Transform in Lebanon and suggested that the active strand is the Roum and not the Yammouneh fault. This work argues that the present day transform fault system fits with a model of circle arc that runs from the Gulf of Aqaba to a triple junction in the Mediterranean southeast of Cyprus via the city of Beirut. Girdler (1990) has proposed the same idea but used the Carmel Fault instead of the Roum Fault. Most of the other authors (e.g. Garfunkel et al. 1981; Bartov 1994) are of the opinion that the transform is the Yammouneh fault. Below, we present satellite imagery and field observations that show that the Roum Fault is not the active segment of the Dead Sea Transform and that the Yammouneh Fault is an active Quaternary structure. This problem of the location of the plate boundary is important for the zonation of seismic hazards.
Northern region. Butler et al. 1997 have argued that the Homs Basalt, located in the northern region of the Yammouneh Fault, and dated c. 5 Ma, unconformably overlies Cretaceous to Miocene sediments without being generally faulted. On the Landsat-TM image, the Yammouneh fault is expressed as a NNE-trending straight line (Fig. 1). It mainly affects Mesozoic-Palaeogene limestones and Mio-Pliocene continental sediments. Southeast of Tripoli along the fault (A in Fig. 1), a small (4.5 km long, 1 km wide) basin, filled with