- Ground-motion model is:
where y is in m∕s2, b1 = -2.622, b2 = 0.643, b3 = -1.249, b4 = 3.190, b5 = 0.344, σevent = 0.0723,
σstation = 0.1198 and σrecord = 0.1640.
- Use two site classes:
- Stiff soil, 360 ≤ V s30 ≤ 750m∕s, 3 stations, 13 records, SS = 1
- Rock, V s30 > 750m∕s, 28 stations, 68 records, SS = 0
V s30 at most stations unknown so use local site conditions to classify stations. Note that there are no deep
alluvium soil deposits in Iceland so basin effects are limited.
- Focal depths between 10 and 15km.
- All earthquakes have strike-slip mechanisms since the South Iceland Seismic Zone is transform zone.
- Develop model to investigate source of variability in ground motions in Iceland not for seismic hazard
- Data well distributed with respect to Mw, rjb and earthquakes (between 9 and 18 records per event).
- Only use high-quality data, following visual inspection.
- Dropped anelastic attenuation term since it was positive.
- Dropped quadratic magnitude term since insufficient data to constrain it, as were magnitude-dependent
distance decay terms.
- Note that low σ could be due to limited records from only six earthquake of similar sizes and mechanisms
and from a small geographical area and few stations.
- Examines single-station residuals (site terms) and single-station σs for a few stations.