This example is taken from central Italy and represents the Fucino Basin source (ID 2), which belongs to the category From Geologic/Geophysical Data. This category stores data on seismogenic sources for which either geological or geophysical evidence is available and that received special attention during the compilation of the Database. For all sources of this group the compiler has brought together geological, seismological and other geophysical information (essentially references and pictures) and has prepared Summaries of the Main Studies on the Source and Comments and Open Questions files (see § 2.2.3 of the Database operating manual for further details). In this particular example the seismogenic source generated the surface-breaking 13 January 1915 Avezzano earthquake; the associated fault scarps are shown with hachured red lines. The figure shows also the Surface Expression and Geometry window, that reports the main geometrical parameters of the source along with the evidence that was used to constrain them. Notice that the button Associated Faults is highlighted: clicking it returns a dialog box with the references from which the data concerning each individual fault scarp were taken.

This example shows the Ovindoli-Pezza source (ID 1), located in central Italy just to the north of the Fucino Plain. Even though it belongs to the category From Geologic/Geophysical Data, this source is not associated with any historical earthquake, and its seismogenic potential was revealed by morphotectonic analyses and paleoseismological trenches exclusively. Also in this case the paleoearthquakes generated surface fault scarps which are shown with hachured red lines. The picture shows also the Seismic Behaviour window, that supplies information and hypotheses concerning the recurrence properties of this source. The parameters reported in this window were either derived from published material, inferred from it, or obtained from other lines of evidence, in which case it is implied that they were calculated by the compilers. These parameters are of critical importance for assessing the hazard associated with each individual earthquake source.

The example presented here is that of the Fano Ardizio source (ID 31), which is also not correlated with any historical earthquake and for which no paleoseismological data exist. Nevertheless the compiler of this source decided to assign it to the category From Geologic/Geophysical Data, because according to her/his own judgement there was enough geological and seismological evidence to constrain its geometry. The source is a NE-verging blind thrust located in the Marche coastal region; its existence was inferred from observations of the adjacent Senigallia source (ID 30), which is related with the 30 October 1930 earthquake, and from observations of the tectonic setting of the surrounding region. Sources like this one are fully-fledged sources, although with a lower reliability rating (C for the Fano-Ardizio source), that may also be considered as seismic gaps. As such, they may have a compelling impact on the assessment of regional seismic hazard. In addition, they usually occur in areas where current knowledge about seismogenic sources is rather poor and that may hide additional, as yet totally unidentified sources.

This picture shows the Irpinia North source (ID 402), located in the middle of the southern Apennines. It is correlated with the 23 July 1930 Irpinia earthquake, and belongs to the category Historical-Well Constrained with Geological Background, which means that the source is one of those derived from good historical data and that some geological information is supplied in the background. This information was not enough for the compiler to turn this source into a Geologic/Geophysical source, but is nevertheless supplied in the same manner as for better quality sources to promote future work and, hopefully, a better understanding of the source characteristics. The Historical-Well Constrained source category includes all seismogenic sources derived exclusively from intensity data following the method proposed by Gasperini et al. [1999] and for which the quality of the solution obtained was enough to allow the representation by an oriented rectangular box. For sources of this group the compiler has brought together support information (essentially references and pictures) and has prepared Summaries of the Main Studies on the Source and Comments and Open Questions files. Notice that all sources belonging to this category are shown in blue if they have geological background, in black if they lack any geological background. Finally, notice that for this category of sources no information can be supplied concerning the dip, rake, and depth of the earthquake causative fault.

The example presented in the picture is that of the Capitanata source (ID 801), located in the Gargano promontory and associated with the 30 July 1627 earthquake. This source belongs to the category Historical-Poorly Constrained, and is represented with a circle having a radius that equals the estimated source length obtained from length vs. magnitude empirical relationships. This means that the source might extend for its entire length in any direction. This category includes all seismogenic sources derived exclusively from intensity data following the method proposed by Gasperini et al. [1999] and for which the quality of the solution obtained was not enough to allow the representation by an oriented rectangular box. Notice that all sources belonging to this category are shown in blue if they have geological background, in black if they lack any geological background.

This example shows the Cagliese source (ID 901), located in the northern Apennines, central Italy. This source belongs to the category Deep, which includes sources derived exclusively from intensity data following the method proposed by Gasperini et al. [1999] and for which the compiler hypothesised a depth larger than ordinary (usually below 10 km). The assignment of a source to this category is irrespective of whether the formal uncertainties in the solution obtained would have allowed to derive a rectangular source or simply a circular source. Notice that in the case of a source deeper than usual the technique proposed by Gasperini et al. [1999] would not be able to derive correctly the true elongation of the source, and any asymmetries in the intensity pattern could more likely result from propagation effects. This source is associated with the 3 June 1781 Cagli (Marche) earthquake.