GNGTS 2013 - Atti del 32° Convegno Nazionale

Intensity-based (preliminary) source inversion of the 1927 earthquake. The prelimary results of the KF source inversion are in Tab. 2 and Fig. 2B. The upper part of Tab. 2 shows the ranges of the parametres explored by the genetic algorithm of the KF inversion (the fault-plane solution was let free); values with “+” and “-” indicate values in the along-strike and anti-strike directions. The lower part of Tab. 2 (please add ±180° to the rake angles) shows the best solution (striking 37°) and the second-choice one. They are not far from each other, indicating an almost flat area in the topography of residuals in the 11-parametre hyperspace. Remember the intrinsic ambiguity of ±180° in the rake angles of our solutions. Thus, the rake angle of Model is 83° or 263°, which could be compatible with the normal faults drawn by Shamir (2006), in the upper part of Fig. 1. Discussion. In the case of earthquakes of the early instrumental era, using also the instrumental recordings is compulsory. For example, the polarities even of few P onsets, in the right geographical positions, could solve the intrinsic ambiguity of ±180° of our solutions. The work is in progress. Acknowledgements. We thank Amotz Agnon of the Hebrew University of Jerusalem for providing selected bibliography and for helpful discussion. Ron Avni from Ben Gurion University for having provided his intensities in the format we needed. Moti Zohar for the conversion of the kilometric coordinates of intensities of the so-called black net to UTM geographical coordinates. We thank the Italian Embassy in Israel for having funded the 1st Italy-Israel Bi-National Symposium (September 2013) on «Earthquakes in Ancient Lands: The Apennines and the Levant», which gave us the opportunity to confront with several Israeli colleagues. The research was partly funded by OGS. References Ambraseys N.; 2009: Earthquakes in the Mediterranean and Middle East, a Multidisciplinary Study of Seismicity up to 1900 . Cambridge University Press, UK, xx + 947 pp.. Tab. 2 - Ranges of the parametres explored by the genetic algorithm of the KF inversion. 127 GNGTS 2013 S essione 1.1