Methodology
1. Probabilistic Seismic Hazard Analysis (PSHA)
Probabilistic Seismic Hazard Analysis (PSHA) forms the basis of risk assessment. It includes:
- Seismic source characterisation (faults + zones)
- Ground motion prediction equations (GMPEs)
- Hazard integration
Hazard integral:
The current analysis uses the design PGA of the official Greek seismic zonation (EAK, FEK 1154B/2003): Zone I 0.16g, Zone II 0.24g, Zone III 0.36g, for a 10% probability of exceedance in 50 years (475-year return period). The pipeline is modular, so a newer hazard model (for example ESHM20 or a new national zonation) can replace the zone values without changing the rest of the analysis.
2. Infrastructure Fragility Curves
Bridge fragility curves follow a lognormal distribution:
λi = median PGA capacity for damage state i
ζ = logarithmic standard deviation
The form follows SYNER-G and HAZUS practice. The λ values are screening parameters per class for moderate damage; extensive damage and collapse use 1.4λ and 1.9λ. In a pilot the parameters are calibrated against the asset owner's inventory and inspection records.
Damage states
- • Moderate
- • Extensive
- • Collapse
Bridge typology
- Class A: λ=0.50g
- Class B: λ=0.35g
- Class C: λ=0.25g
- Class D: λ=0.15g
3. Building Stock Vulnerability
In a pilot, building stock vulnerability is estimated with the EMS-98 taxonomy, using construction era as a proxy for the seismic design code:
| Period | Code | Vulnerability |
|---|---|---|
| Pre-1959 | No code | Very high |
| 1959–1984 | 1959 code | High |
| 1985–1995 | 1959 code + 1984 supplementary clauses | Moderate |
| Post-1995 | ΝΕΑΚ 1995 / ΕΑΚ 2000 / EC8 | Low |
Source: ELSTAT 2021 building census, national coverage at municipality level.
Data Sources
| Data | Source | License | Use |
|---|---|---|---|
| Seismic hazard | EAK, FEK 1154B/2003 | Public | Design PGA per zone |
| Real-time earthquakes | NOA FDSN/EIDA, EMSC | Open | Live feed |
| Bridges | OpenStreetMap | ODbL | Infrastructure |
| Fragility curves | SYNER-G / HAZUS type | Screening parameters | Bridges |
| Building stock | ELSTAT 2021 building census | Open | Vulnerability (pilot) |
| Municipality boundaries | OpenStreetMap | ODbL | Layer |