Engineering Analysis of Strong-motion Data Recorded During German Task Force Missions To Turkey (1998-2000)
Abstract
Obviously, structural damage caused by strong earthquakes can not only be attributed to defects in design or construction, but rather the widely discussed phenomenon of local site effects has to be considered as well. In the last decade extensive strong-motion measurements were carried out by the reconnaissance team of the German TaskForce for Earthquakes. Missions to Turkey in 1998 (Adana, Ceyhan) and in 1999 (Izmit/Kocaeli and Duezce) provided a unique database of recorded aftershocks at sites where building damage occurred. To gain more insight into the effect of local site conditions post-earthquake investigations were initiated in Adana and Kocaeli (October 2000). Microtremors were recorded at sites of the previously installed strong-motion accelerographs and locations of evident concentration or variation of building damage spreaded over the area of main shaking effects. The predominant frequencies and amplification potential at recording sites were identified by H/V spectral ratio method. On the basis of H/V-spectra the sites were classified (into soft soil, stiff soil, rock-type conditions) enabling more detailed studies of recorded strong motion data which were obtained by previous TaskForce missions. Attenuation laws for spectral and peak ground acceleration were statistically determined similar to the approach by Ambraseys et al. (1996). As it can be concluded, the differences between ground motion on soft and stiff soil are less pronounced and of a similar level of amplitudes. It has to be emphasized that the studies are supported by different data types referring to an unique and consistent data-set. Thus, conclusions concerning the reliability of recently applied site response estimation techniques will be derived in dependence on soil conditions. Finally, it will be discussed to which extent subsoil conditions are responsible for the enforcement of building damage. For this purpose and in relation to geological features, a macroseismic map of shaking effects (intensity) was prepared taking into consideration the results of a damage survey undertaken immediately after the 1999 Izmit/Kocaeli earthquake as well as meanwhile presented intensity assignments of other research groups. As a result, instrumentally investigated (micro)sites are correlated with macroseismic shaking effects.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.6333S