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New Version of the Earthquake Mechanism of Mediterranean Area (EMMA) Database With a Web-Gis Interface

Description: 

We present a new version (4.0) of the database of Earthquake Mechanisms of the Mediterranean Area (EMMA) of “checked” first-motion focal solutions available from the literature. The EMMA database, developed on MS-ACCESS and managed by original software, uniforms the different formats of the data available and try to solve misprints, inaccuracies and inconsistencies that make them almost useless for other users (e.g. tests the perpendicularity of nodal planes and/or P and T axes of all solutions and, when both axes and planes are given, even their mutual consistency). The database now collects more than 34,000 focal solutions (~+ 850%, ~560%, ~ +280% with respect to previous three existing database versions). The EMMA database is not a homogeneous catalogue because it includes focal mechanisms computed with different methodologies covering different areas and magnitudes, depending on original papers available. We added the missing parameters (e.g. time, magnitude) and, when possible, we link the data to the earthquakes available in other catalogues (e.g. HOmogenized instRUmental Seismic catalog-HORUS-, International Seismological Centre -ISC-). We merged EMMA with the focal mechanisms (mainly by moment tensor inversion) from different available on-line catalogues ;at global and regional scale (e.g. GCMT, RCMT). An automatic procedure, based on several criteria, permits to choose the most “representative” (preferred) solution when more than one solution is available for a same earthquake comparing quantitatively the alternative solutions (e.g. Kagan angle between solutions, Frohlich ternary diagram representation).

A web-GIS interface based on OpenLayers (an open-source javascript library) allows now to select (e.g. for areas, magnitude range, time period), display and export the data suitable to be handled by graphic software and user written procedures. The EMMA database is a powerful tool for characterising the tectonic regime and for seismotectonic and deformation analyses, extending the data coverage of other catalogues available for the Mediterranean area over time and to a lower magnitude threshold.

Session: Understanding and Quantifying the Variability in Earthquake Source Parameter Measurements [Poster Session]

Type: Poster

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Gianfranco

Student Presenter: No

Invited Presentation: 

Authors