In order to identify hazards to which a given dam is prone, the following types of maps are relevant:
- Digital elevation maps for modelling potential flood effects.
- Geological maps showing the earth material on which the dam is erected.
- Active tectonic fault maps as possible earthquake and slow deformation sources.
- Seismic hazard maps, presenting the expected earthquake impact for a given site.
- Geomorphologic maps, delineating possible sources of mass-movement (e.g. landslides, debris flows).
A flood modelling map shows the height and speed of the flood wave and the flood dynamics in the time domain:
The main dam-related hazards are seismic shaking and overtopping due to landslide descent or large floods. The dam should be designed to resist the expected intensity of shaking (i.e. the so-called maximum design earthquake MDE). For calculation of the potential seismic impact, the maps of active tectonic faults of the area are compiled first. The intensity and recurrence interval of earthquakes generated by these faults are then assessed and finally the impact of the earthquake (the so called spectral ground acceleration) on the dam area is calculated. It is important also to take into account the site (soil) conditions and to know the natural frequency of shaking of a dam, because the dam is most vulnerable at this frequency.
If all this information is taken into account during design and construction of the dam, the seismic resistance of the dam structure is guaranteed.