Abstract. This paper presents a methodological approach to seismic hazard assessment
based on a hybrid source model composed of faults as independent entities and
zones containing residual seismicity. The seismic potential of both types of
sources is derived from different data: for the zones, the recurrence model
is estimated from the seismic catalogue. For fault sources, it is inferred from
slip rates derived from palaeoseismicity and GNSS (Global Navigation Satellite
System) measurements. Distributing the seismic potential associated with each source is a key
question when considering hybrid zone and fault models, and this is normally
resolved using one of two possible alternatives: (1) considering a
characteristic earthquake model for the fault and assigning the remaining
magnitudes to the zone, or (2) establishing a cut-off magnitude, Mc, above
which the seisms are assigned to the fault and below which they are
considered to have occurred in the zone. This paper presents an
approach to distributing seismic potential between zones and faults without
restricting the magnitudes for each type of source, precluding the need to
establish cut-off Mc values beforehand. This is the essential difference
between our approach and other approaches that have been applied previously. The proposed approach is applied in southern Spain, a region of
low-to-moderate seismicity where faults move slowly. The results obtained
are contrasted with the results of a seismic hazard method based exclusively
on the zone model. Using the hybrid approach, acceleration values show a
concentration of expected accelerations around fault traces, which is not
appreciated in the classic approach using only zones.
The use of Monte Carlo simulations for seismic hazard assessment in the U.K.
