- Ground-motion model is:
where y is in g, V ref = 1130m∕s, C1 = -4.407, C2 = 1.142, C3 = -0.012, C4 = -1.450, C5 = 0.140,
C6 = 0.623, C7 = -0.389, C8 = -0.057, C9 = 0.188, τ = 0.322 (inter-event), σ = 0.530 (intra-event),
τS = 0.230(site-to-site), σR = 0.477 (record-to-record sigma), τP = 0.337 (path-to-path), σ0 = 0.338
(remaining unexplained variability) and σT = 0.621 (total).
- Use V s,30 to characterise sites. 110 ≤ V s,30 ≤ 1056.71m∕s. Good distribution of data between about 200
- Classify events into 3 mechanisms:
- Strike-slip. FN = FR = 0.
- Normal. FN = 1 and FR = 0.
- Reverse. FR = 1 and FN = 0.
- Focal depths between about 1 and about 32km with most between 5 and 20km.
- Use data from the Taiwan Strong Motion Instrumentation Program from crustal earthquakes between 1995
and 2009. All selected events have at least 50 records.
- Baseline correct and filter data using procedure of Pacific Earthquake Engineering Research Center.
- Most data from Mw < 6.5 and R > 20km.
- Develop maximum-likelihood method (the path diagram) based on mixed-effect model to quantify path
effects for each station. Divide record-to-record residuals into small brackets in a rose diagram for 6
source-to-site distance bins (< 50, 50–100, 100–150, 150–200, 200–250 and 250–300km) and 8 azimuth bins
(every 45∘). Then estimate mean residual for each path bin. Obtain 8 × 6 = 48 path bins (path-to-path
residuals) at a site and hence compute repeatable path term for all path-to-path residuals for all stations.
- Examine path diagrams for 8 stations in the Ilan Plain as an example. Find similar results.
- Examine path-to-path residuals w.r.t. azimuth and distance. Find no recognizable trends for azimuth.
Path-to-path residuals become smaller as distance increases but note could be due to having fewer data
at long distances.
- Estimate τP and σ0 for each station. Find geographical patterns in these values.
- Also apply Closeness Index (CI) approach (Lin et al., 2011a). Find similarities and differences (e.g. CI
approach leads to slightly higher σ0 estimates) between results from the two methods.