An Atlas of Mediterranean seismicity

The CD-ROM as well as the web pages contain an extensive collection of maps made by GMT (Wessel and Smith, 1991) reporting the seismicity of the Africa-Eurasia margin from the Central Atlantic to Iran. Focal mechanisms, taken from seismic moment tensor catalogs (mainly the Harvard CMT catalog and the Euro-Mediterranean regional centroid-moment tensors RCMT catalog) as well as from a recent extensive compilation of literature solutions (EMMA, Vannucci and Gasperini, 2003, 2004), are plotted for the entire area and for eight seismic provinces (Atlantic, western Mediterranean, central Mediterranean, Aegean, Anatolia and Dead Sea, Caucasus and Persia, northern Europe). For four areas of high seismicity (central Mediterranean, Aegean, Anatolia and Dead Sea, Caucasus and Persia), focal mechanisms sums over regular grids, with mesh of 1 and 0.5 degrees, are also plotted in terms of average mechanisms and seismic strain eigenvectors. A collection of summary cards for each non empty cell within the study area is also provided. These give a visual and quantitative comparison of the relative contribution given by the EMMA database and the moment tensor catalogs to the moment tensor sum. The cards also include maps of the focal mechanisms within the cell, as well as some summary indicators, useful to evaluate the consistency and the relative coherency of the different datasets. In particular, we indicate the total number of mechanisms in the cell, the number of mechanisms, the average source depth and the cumulative scalar moment. To evaluate the reliability and coherency among different sources of data, we also report the average depth difference, the ratio between cumulative scalar moments and the minimum rotation angle between best double couples (Kagan, 1991). Sensitive maps allow the summary cards to be accessed by clicking on cells including mechanisms. For Italy we also made summary cards accessible for the areas of the most recent seismogenic zonation ZS9 (ZS9 Working Group, 2004) used for recent seismic hazard computations. References Kagan Y.Y., 1991. 3-D rotation of double-couple earthquakes sources, Geophys. J. Int., 106, 709-716. Vannucci G., Pondrelli S., Argnani A., Morelli A. Gasperini P. and Boschi E., 2004. An Atlas of Mediterranean seismicity, Annals of Geophysics, Supplement to V. 47, N.1, 247-306. Vannucci G. and Gasperini P., 2003. A database of revised fault plane solutions for Italy and surrounding regions, Comput. Geosci., 29, 903-909. Vannucci G. and Gasperini P., 2004. The new release of the database of Earthquake Mechanisms of the Mediterranean Area (EMMA Version 2). Annals of Geophysics, 47, 307-334. Wessel, P., Smith, W.H.F., 1991. Free software helps map and display data, Eos Transactions of the AGU, 72, 441. ZS9 working group (2004). Redazione della mappa di pericolosità sismica prevista dall'Ordinanza PCM del 20 marzo 2003. Rapporto Conclusivo per il Dipartimento della Protezione Civile, INGV, Milano-Roma, aprile 2004, appendice 2. Available at http://zonesismiche.mi.ingv.it/documenti/App2.pdf.