The Influence Of The Geological Condition On Theincrease Of The Earthquake Effects (Earthquake On April 12, 1998; Posocje, Slovenia)

On 12 April 1998, the strongest earthquake in the last century with an epicentre in Slovenia shook low a populated area in the Alps (The upper Soca Territory) of NW Slovenia. The earthquake of a local magnitude of 5,6 (MwA=6,0) caused no loss of life, although a lot of damage was done to the buildings and landscape. 3390 damaged buildings were registered at that time, 160 of them were declared structurally unsound (damage of the 5th degree). Unique characteristics of the earthquake were in the number and variety of the consequences to the landscape, ranging from big rock fall to small cracks in the rock itself. To determine the influence of the geological condition on the increase of the earthquake effects, we had to take in to account not only the damage done to the architecture but also to the landscape. This was necessary, as only the valleys are inhabited, whereas in the alpine areas we only find dairy farms, hunting lodges, mountain huts and individual mountain farms. Analysis ofthe damage done to the buildings shows the correlation between the greatness ofthe damage and the type and age ofthe building, quality ofthe foundation, walls, roof, and the general design characteristics. The detailed analyses of the damage done to the landscape determined the variety in types of damage to the landscape, the connection of the damage with the earthquake intensity and more specific determination of the location ofthe earthquake epicentre. As the basis for determination of increased earthquakes effects we used a reambulated Geological map in the scale of I:25000 as it was made for purposes like this. We also used a lot of other data on geological, geomechanical and geophysical ground/soil attributes, that were gained as the renewal in that area began.