ASSESSMENT OF SEISMIC HAZARD FOR INTRACON TINENTAL AREAS - THE SITUATION IN CENTRAL-EUROPE

In Central Europe damaging earthquakes are caused by moment magnitude Mw < 6 earthquakes. Such events take place in the uppermost 15 km of t he earth's crust as horizontal strike slip or normal faulting. The mai n part of seismic activity is observed in the area of the Rhenish grab ens. In the northwestern part of Central Europe (E-Belgium, S-Netherla nds, NW-Germany) normal faulting prevails, the southern part of the st udied area is dominated by horizontal strike slip motions. The observe d recent tectonic movements are the consequence of the regional tecton ic stress field showing a relatively uniform orientation of its main p rincipal stress vector striking NW-SE. The slip rates along shearzones are less than 0.1 mm/a. Seismic reactions an concentrated to intersec tions of differently striking fault systems. Ground motions are strong ly altered by the influences on seismic waves travelling throughout ge ological structures to the earth's surface. The macroseismic effects a re strongly controlled by the relation between natural frequencies of shaken buildings, the frequency of maximum transfer through the underg round and the corner frequency of the focal process. In the case of id entity or similarity of the frequences steming from different domains of the earthquake systems an important technical influence of ground m otions on a building can be assumed. Dynamic aspects of the seismic so urce as the Doppler effect produce a typical pattern of technical infl uences in the epicentral area producing quite different types of damag es.