- Based on Zhao et al. (1997) see Section 2.153
- Ground-motion model is: where PGA is in m∕s2, R = and Rv is distance travelled by direct seismic wave through volcanic
region. A5 only for crustal reverse, A6 only for interface, A7 only for strong and weak rock, A8 only
for strong rock, A9 only for strong rock, A1 = 0.2955, A2 = -1.603, A3 = 0.00737, A4 = -0.3004,
A5 = 0.1074, A6 = -0.1468, A7 = -0.00150, A8 = 0.3815, A9 = -2.660, A10 = -0.0135, d = 19.0 and
σ = 0.24.
- Originally considers five site categories but retain three:
- Strong rock: V s > 700m∕s
- Weak rock: 375 ≤ V s ≤ 700m∕s and category AV those sites with a very thin layer (≤ 3m) overlying
- Soil: everything else
- Depth to centroid of rupture, hc, used, 4 ≤ hc ≤ 94km.
- 60% on soil, 40% on rock
- Consider tectonic type: C=Crustal (12+17), I=Interface (5+0) and S=Slab(8+0)
- Consider source mechanism: N=normal (6+1), R=reverse (12+5) and S=strike-slip (7+11). Mixed
classified by ratio of components ≥ 1.0.
- Mixture of analogue and digital accelerograms (72%) and seismograms (28%)
- Accelerograms sampled at 100–250 samples/sec. Bandpass frequencies chosen by analysis of Fourier
amplitude spectrum compared with noise spectrum. fmin between 0.15 and 0.5Hz and fmax equal to 25Hz.
Instrument correction applied to analogue records.
- Seismograms sampled at 50–100 samples/sec. Differentiated once. Instrument corrected and high pass
filtered with fmin = 0.5Hz. No low pass filter needed.
- Clipped seismograms usually retained.
- Directional effect noticed but not modelled.
- Most records from more than 100km away. Note lack of near-source data.
- Records from accelerograms further away than first operational non-triggering digital accelerograph, which
had a similar triggering level, were excluded.
- Models difference between high attenuating volcanic and normal regions.