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58 Earthquake Engineering

which causes energy radiation of different fault parts in different times and seismic waves

Let's compare amplitude spectra of obtained design accelerograms with spectrum of real earthquake from considered fault. Data analysis (fig. 18 and fig. 19) shows that spectra of

It must be noted that spectrum of vertical component of real earthquake is closer to design spectra. The last fact is quite obvious and is explained by proximity to earthquake source. Indeed, close earthquakes in general are characterized by predomination of vertical component. Record of TEA station (located in theater) was selected due to its location on

Analysis of spectrum of weak earthquake shows that peaks are observed on 1.3 and 5.6 Hz (Fig. 18). In spectra of synthesize accelerograms mentioned amplitudes are also observed. At the same time medium response on strong earthquake, undoubtedly, differ from weak

**Figure 19.** Spectra of design accelerograms at different source locations of earthquake М=7,1: 1 –

**Figure 20.** Spectra of accelerograms of weak earthquake with epicenter in the zone of Vladikavkaz

western part of fault; 2 – middle part of fault; 3 – eastern part of fault

fault. (25.08.2005 10:25 GMT, H = 8 km M= 2.5).

are interference and causes directivity effects (Beresnev & Atkinson, 1997, 1998).

calculated and real earthquakes in a whole are similar in their main parameters.

dense gravel and has a minimal distortions caused by soil conditions.

earthquake response (Fig. 19) (Zaalishvili, 2000).

V. B. Zaalishvili *Center of Geophysical Investigations of RAS, Russian Federation* 
