- Ground-motion model is:
Select this form to compare results with Berge-Thierry et al. (2003).
- Use five Eurocode 8 categories:
- V s,30 > 800m∕s, use S1
- 360 < V s,30 < 800m∕s, use S2
- 180 < V s,30 < 360m∕s, use S3
- V s,30 < 180m∕s, use S4
- Soil D or C underlain in first 20m by a layer of V s,30 > 800m∕s, use S5
where V s,30 is average shear-wave velocity in upper 30m. Since soil profiles only available up to 20m,
use method of Atkinson and Boore (2003) to assign sites to categories using Kik-Net profiles to define
probability curves. Generate five redistributions to test stability of results. Find coefficients and σ relative
stable (changes less than 10%) except for site class A (changes up to 50%.
- Response parameter is pseudo-acceleration for 5% damping.
- Use data from the K-Net and Kik-Net networks.
- Process records using non-causal 4 pole Butterworth filter with cut-offs of 0.25 and 25Hz for consistency
with earlier studies.
- Select records from events with Mw > 4 and with focal depth < 25km to exclude records of subduction
events and to remain close to tectonic conditions in France.
- Exclude records from distances greater than a the distance predicted by a magnitude-dependent equation
predicting the location of a PGA threshold of 10cm∕s2 (corresponding to trigger of older Japanese sensors)
to prevent possible underestimation of attenuation rate.
- Visually inspect records to check for glitches and to use only main shock if multiple events present.
- Convert MJMA to Mw to compare results with other studies.
- For 10 large earthquakes for which source dimensions are known use rrup.
- Note good distribution w.r.t. Mw and rrup except between 6.1 and 7.3 where only two events.
- Find that pseudo-acceleration at 0.01s equals PGA.
- Also compute coefficients using geometric mean and find identical coefficients and standard deviations
lower by 0.02.
- Find σ lower when use five site classes than when no site information is used.
- Find peak in σ at about 1s. Peak also present when unfiltered data used. Also present when data from
different magnitude ranges (4.0–4.5, 4.0–5.0, 4.0–5.5 and 4.0–6.0) are used.
- Note that results for site class E are uncertain due to limited number of records.
- Examine residuals w.r.t. distance and magnitude and find no significant bias.
- Examine quartile plots of residuals and find that residuals are normally distributed up to 2–4 σs. All pass
Kolmogorov-Smirnov test at 5% significance level for normality except at 0.01s.
- Conducted sensitivity analysis by changing minimum magnitude, geographical area and minimum number
of events recorded at each station. Find dependence of σ on period was similar as were site coefficients. b
shows some variations.
- Coefficients not reported.