Sources from Geological/Geophysical Data

(Type A sources)

These are the best quality sources with a potential for an earthquake of M 5.5 or larger. In several cases they benefit from instrumental and/or historical data. In either case, there has been geological work aimed at identifying field evidence for the given source, or at least at providing geological, tectonic or geodynamic constraints to identify and locate it with the smallest possible uncertainty.

These sources are described tri-dimensionally by the rectangular rupture plane that best approximates the expected or observed or inferred earthquake rupture. In the cartographic interface they are represented by a rectangle, that corresponds to the surface projection of the rupture plane, and by a line drawn next to one of the long edges of the rectangle, that corresponds to the geometric intersection of the rupture plane with the topography at sea level. For surface-breaking faults this line will appear very close or coincident with one of the edges of the rectangle, while for blind faults there will be a gap that is a function of dip and depth of the fault plane. All rectangle and line edges are precisely located with their N latitude and E longitude. The inferred length, width, depth, strike, dip and kinematics (rake) of the source conclude its geometric description.

The reliability of each source is expressed by a single Quality parameter that ranges from A (most reliable) to D (least reliable). See the description of Rating Criteria for further details.

The recurrence properties of the source are optionally described by its slip-rate, average recurrence interval, timing of the latest and penultimate earthquakes, and time elapsed since the latest event.

The description of sources of this category is optionally complemented by:

1) a list of Bibliography that includes all papers that mention the source specifically plus a number of papers that deal with the geology, tectonics and historical seismicity of its region;

2) a text named Previous Studies that summarises all the work carried out on the given source by previous workers and the level of knowledge achieved before the beginning of FAUST;

3) a text named Open Questions that presents the basis of some of the decisions made in the definition of the source parameters and summarises aspects of the source that still need to be investigated or await confirmation.