The occurrence of devastating earthquakes highlights the importance of carrying out seismic hazard assessments in order to estimate the consequences of these events. While good progress has been made in predicting earthquakes, their time of occurence, magnitude and location can not be yet forecast with certainty. Therefore, it is important to carry out seismic hazard assessments because, although it is not going to eliminate potential damages, it will help to significantly reduce their negative impacts.
The seismic hazard assessment involves the quantitative estimate of a seismic threat in a particular location. That seismic hazard can be analized in a deterministic manner, taking into account a specific seismic scenario, or in a probabilistic manner, taking explicitly into account the uncertainty regarding the earthquakes’ size, location, and occurrence time. Furthermore, the seismic hazard assessment makes it possible to estimate the potential damages and losses in a region caused by future earthquakes; in other words, it includes the evaluation of the performance of structures in the face of the seismic threat in the area where these are located.
The basic steps of a procedure of regional seismic hazard assessment include:
- Identification of seismogenic sources.
- Earthquake occurrence models in these sources.
- Estimation of the attenuation of seismic movements between the source and the region.
- Evaluation of local site effects such as seismic amplification, liquefaction, landslides, and superficial manifestations of fault ruptures.
- Estimation of damages in regional inventories.
- Estimation of the expected losses in the region.