To quantify the variations of the site responses in downtown Bucharest the horizontal- to vertical-component spectral ratio method (H/V) on different kinds of seismic data was applied. Starting September through November 1997 we have recorded ambient seismic noise at 16 sites in Bucharest. In addition, we used ambient noise and small earthquake records from the instruments which had been deployed during an aftershock campaign in June/July 1990. Furthermore, we have examined S-waves of strong Vrancea earthquakes.The ambient noise ratios, determined on two profiles which cross in the center of Bucharest, show a remarkable constancy of the main resonance period. They range in a narrow band from 1.2 to about 1.6 seconds with an average value of T1=1.36±0.14 s. A second but small amplitude resonance at even greater periods is recognizable with T2=5.22±0.9 s.First recordings of Vrancea earthquakes by the new K2 network corroborate that the high frequency peak ground accelerations (PGA) may differ up to 2–3 times in downtown Bucharest. However, lowpass filtering with a corner frequency of 1Hz reduces these differences from several 100% to about ±15%, thus confirming the almost constant level of the main soil resonance at an average period of about 1.4 seconds of the noise data in downtown Bucharest.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- A Note on Empirical Site Responses in Bucharest, Romania
- Springer Netherlands