*2.2.4. Factors strengthening the tsunami disaster*

Several case studies indicated that splay faults are associated with subduction zones in the world [3, 11]. They develop within the sedimentary sequences as sediments being added from the upper plate. The superimposed effect of splay faulting on tsunami wave heights in the near-field has been observed in many mega-tsunami events. In this respect, the 1946 Nankai, 1960 Chilean and 1964 Alaskan earthquakes and tsunamis [8, 14] and the most recent case of the 2004 Sumatra-Andaman could be mentioned.

Thus, splay faults can play an important role, in particular, as local hazard, and thus their identification is important.

At this stage, we do not believe that these faults individually are capable of producing tsunami, but as indicated above, they can play an important role in strengthening the tsunami hazard effect during megathrust ruptures. So, we strongly suggest that this factor should be accounted for a comprehensive tsunami hazard analysis. These factors in addition to the above-men‐ tioned items, if are not implemented accurately, will make the design of an effective tsunami early warning system problematic [15].
