Natural hazards mapping of mega sea waves on the NW coast of Egypt

Some boulder fields were deposited by the sea waves during winter storms or by paleo tsunami mega waves and most of these boulders were uprooted from the marine platform and distributed within 90 m of the shoreline, are found up to 4 m above present mean sea level.The objective of this work is defining systematic characterisation of the high-energy depositional contexts working by storms or paleo tsunami deposit, and to reconstruct the history of mega block deposition along the study area, depends upon extensive field surveying and geomorphic mapping by using GIS and GPS techniques as well as statistical analysis of boulders in order to determine both extreme events using the significant wave height and period of maximum observed storms and historical tsunamis along the study area, as well as geomorphic hazard mapping and samples dating.The results show that both possible processes (storm and tsunami waves) can deposit these boulders, it attested at Alexandria for example by the archaeological excavations and historical sources. Tsunami waves and storms cause the displacement of huge boulders from sea bottom and submersible marine terraces (platforms) to the beach due to its major power and ability of carving and graving it is also capable of pulling other boulders from the land and redeposit it on the beach or coastline.