EGU General Assembly 2019, Vienna, Austria, 07 April 2019, vol.21, no.3319, pp.1
The promotion of earthquake research in Japan covers comprehensive basic policies for the promotion of seismic
research through the observation, measurement and survey of earthquakes. HERP (Headquarter for Earthquake
Research Promotion) proposed a framework of survey and observation plan of earthquakes in Japan. At the first
stage of this framework, it consists of observation of crustal activities and surveying of underground structures.
Next step is to improve the methods of predicting strong ground motion and increase accuracy, and thus the
improvement of seismic hazard maps. In order to fully capture the seismic hazard of a region, we must understand
the effects of the regional 2D/3D underground structure on wave propagation. Selection and modification of ground
motion time series to represent a specific hazard at a site has a large impact on the results of nonlinear response
history analyses using these input motions, indicating the need to establish rational procedures for ground motion
selection, scaling and modification. Validated seismological methods may be used to generate ground motion
time series that incorporate near-fault rupture directivity effects and basin effects, and appropriately represent the
duration and long period energy content of these large design events. These effects cannot be fully predicted by
simply adopting GMPEs that are developed for other regions. The main objective of this project is to determine
time-histories for distant and near-field earthquakes through ground motion simulations.
This joint project proposes to investigate the validation of the modeling procedure of determination of geological
models proposed by HERP for seismic hazard map in Japan, and output of this validation will be applied to
the Eskisehir basin in Turkey. We can understand the performance of the procedure through the application to
the Kumamoto area by the Japanese side (using HERP procedure), and will be compared with the results from
Eskisehir by Turkish side. We also incorporate the methods used in the Japanese procedure into estimation of
geological models in the Eskisehir basin. In this frame, we attempt to calculate broadband period ground motion
time series from near-field and far-field earthquakes by using source modeling and ground motion techniques. The
effects of ground motions having a broadband period range can be studied in two parts; first one is the rupture
directivity effects and secondly basin edge effects. The prediction and simulation of such ground motions need
source modeling, determination of 2D/3D basin geometry and S-wave velocity structure.
We performed both array- and single-station microtremor measurements at a number of locations so as to characterize
the area to determine 1-D S-wave velocity structures down to the bedrock depth beneath the strong motion
sites for the broadband simulation. Final geological models obtained will be verified by seismic interferometry
method and microgravity measurements. As next step, we make ground-motion simulations to get time histories
to analyze the effects of ground motions to buildings. In spite of increasing number of buildings having different
heights and characteristics in urbanized areas in Turkey, a few studies exist on the interaction of such buildings
with ground motions having broadband periods.
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