Ground motion amplification in sedimentary basins
In several megacities such as Mexico City, Los Angeles and Kobe, which are located atop large sedimentary basins, violent ground motions and prolonged shaking, caused considerable loss of life and structural damage. These observations indicate that ground motion is sometimes locally greatly amplified, however, direct correlation between the degree of amplification and specific geological features is yet unclear.
For the first time in Israel we simulate ground motion amplification in sedimentary basins in 2-D and 3-D. For this we combine subsurface knowledge with numerical modeling capabilities that simulate seismic wave propagation in geometrically complex structures. We use an Earthquake Simulations Cluster (ESC), which was built within a joint GSI-BGU project. Up to date we modeled the Dead Sea basin, the coastal plain, and the Zevulun Valley.
The Dead Sea Transform (DST) is the source for some of the largest earthquakes in the eastern Mediterranean. The seismic hazard posed by the DST threatens the Israeli, Palestinian, and Jordanian populations alike. Several deep and structurally complex sedimentary basins are associated with the DST. These basins are up to 10 km deep and typically bounded by active fault zones. The low seismicity of the DST, the sparse seismic network, and limited coverage of sedimentary basins result in a critical knowledge gap. Therefore, it is necessary to complement the limited instrumental data with synthetic data based on computational modeling, in order to study the effects of earthquake ground motion in these sedimentary basins.
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Coastal plain and Zevulun Valley
Zones with potentially high ground motion amplification
The map of zones with potentially high ground motion amplification is based entirely on geological data, highlighting areas where high impedance ratio is expected at relatively shallow depth. This map was adopted by the Israeli building code, requiring a site specific survey for important buildings that are designed in the highlighted areas.
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