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Www.spice-rtn.org Mid-Term Review Meeting, February 13-14, Tutzing Seismic wave Propagation and Imaging in Complex media: a European network IVO OPRSAL.

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Presentation on theme: "Www.spice-rtn.org Mid-Term Review Meeting, February 13-14, Tutzing Seismic wave Propagation and Imaging in Complex media: a European network IVO OPRSAL."— Presentation transcript:

1 Mid-Term Review Meeting, February 13-14, Tutzing Seismic wave Propagation and Imaging in Complex media: a European network IVO OPRSAL Experienced Researcher Host Institution: CUP Prague Place of Origin: Czech Republic Appointment Time: July 2005 Project: Forward and inverse modelling of finite-extent earthquake source by PEXT and FD method. Task Groups: Local scale Cooperation: INGV Rome, GFZ Potsdam, ETH Zurich, AIST Tsukuba IVO OPRSAL Experienced Researcher Host Institution: CUP Prague Place of Origin: Czech Republic Appointment Time: July 2005 Project: Forward and inverse modelling of finite-extent earthquake source by PEXT and FD method. Task Groups: Local scale Cooperation: INGV Rome, GFZ Potsdam, ETH Zurich, AIST Tsukuba

2 Mid-Term Review Meeting, February 13-14, Tutzing Project Scope Kinematic finite-extent source modelling The Turkey-Flat strong motion "blind" prediction - international experiment The Turkey Flat strong-motion experiment is the forth of the blind prediction experiments, where the Prague group takes a part: - Turkey Flat (Parkfield) weak motion test (1987) - Ashigara valley (Odawara, 1992) - Hyogo-ke n Nanbu earthquake (aka Kobe EQ) (Yokohama, 1998) Parkfield M6 earthquake (USA, 2006), The tests are conducted under ESG(Effects of surface geology working group of IASPEI/IAEE), the 2006 ESG meeting will take place in Grenoble. More about the present Turkey-Flat strong-motion test can be found at the California Geological Survey page

3 Mid-Term Review Meeting, February 13-14, Tutzing “Blind” Test Approach Conduct high quality field and laboratory tests to characterize the geotechnical properties of the site Collect high-quality measurements of ground response in sediment basin and bordering rock Distribute only rock records and request predictions at basin recording sites Release observed basin recordings of and compare with predictions

4 Mid-Term Review Meeting, February 13-14, Tutzing Phase I : R1 predictions (required synthetics: R2,V1,V2,D1,D2,D3) Phase II: D3 predictions (required synthetics: R2,V1,V2,D1,D2) D3 D2 D1 R1 V1 V2 R2

5 Mid-Term Review Meeting, February 13-14, Tutzing Required Strong-Motion Predictions Two-step process: R1 predictions Then: D3 predictions Fourier Amplitude Spectral Ratios: –1) X i /R1 given R1 (where X i means D1, D2, D3, V1,V2, R2) –2) V1/D3, D2/D3 given D3 Acceleration Time Histories: –(1) V1, D2, D3 given R1 –(2) V1, D2 given D3 Psuedovelocity Response Spectra (5% damped) & peak values displ, vel, accel: –1) X i given R1 (where X i means D1, D2, D3, V1,V2, R2) –2) V1, D2 given D3 D3 D2 D1 R1 V1 V2 R2

6 Mid-Term Review Meeting, February 13-14, Tutzing Turkey Flat strong-motion prediction by the finite-extent source modelling Usual approach is to focus on local site effects while the excitation is represented by plane incident waves. Composite-source method using a non-uniform fault slip distribution (Ji, 2005) is applied to all stations. We emphasise the source effect. The reason is that: Firstly, the studied stations (R2, V1, V2, D1, D2, D3) are inside or around a very shallow stiff-soil sedimentary valley (local effects can be treated using individual 1D models below each receiver). Secondly, the dimensions of the ruptured area (W x L = 15 x 40 km, M6) are too large to be approximated by a planar wave.

7 Mid-Term Review Meeting, February 13-14, Tutzing Turkey Flat situation San Andreas Fault - projection of ruptured area Turkey Flat hypocenter

8 Mid-Term Review Meeting, February 13-14, Tutzing Turkey Flat strong-motion prediction by the finite-extent source modelling Free parameters of the source model are tuned by fitting the available acceleration time history and spectrum at R1 (reference rock site) Acceleration (m/s^2)

9 Mid-Term Review Meeting, February 13-14, Tutzing Turkey Flat strong-motion prediction by the finite-extent source modelling ADVANTAGE: Synthetics (0-40Hz) at the studied stations R2, V1, V2, D1, D2, D3 (with individual 1D models) are obtained with the same source model as that used for R1  i.e. realistic description of the incoming wave filed

10 Mid-Term Review Meeting, February 13-14, Tutzing Turkey Flat strong-motion prediction results

11 Mid-Term Review Meeting, February 13-14, Tutzing Availability of D3 record did not require any additional change. This is an a posteriori justification of the approach Turkey Flat strong motion Prediction, PHASE II NO MORE WORK NEEDED !

12 Mid-Term Review Meeting, February 13-14, Tutzing Outlook I Modelling the data for predicted stations after they are released and benchmarking/comparison to solutions of other modellers.

13 Mid-Term Review Meeting, February 13-14, Tutzing Outlook II Weakness of discussed approach: ground motion modelling was tested at 2 points only (R1, D3) Hence, general applicability of the source modelling will be tested using accelerograms from more CISN stations distributed around the fault.


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