AN INNOVATIVE APPROACH FOR ASSESSING EARTHQUAKE INTENSITIES: THE PROPOSED INQUA SCALE BASED ON SEISMICALLY-INDUCED GROUND EFFECTS IN THE ENVIRONMENT

The debate originated within the Workshop of the Subcommission on Paleoseismicity held during the XV INQUA Congress in Durban, August 1999, emphasized the importance of developing a multi-proxy empirical database on earthquake ground effects that can be used by, and incorporated into, seismic-hazard assessment practices. The Subcommission selected this task as the primary goal for the past inter-congress period. An interdisciplinary Working Group (WG) was established, including geologists, seismologists and engineers, in order to formalize the collected data into a new scale of macroseismic intensity based only on ground effects: the proposed new INQUA scale.

This paper illustrates the results of the research conducted by the WG, introduces the INQUA scale, and discusses major issues related to this innovative approach to the intensity assessment. The INQUA scale first draft is due to Leonello Serva, based on the compilation and comparison of the three most commonly used intensity scales, i.e., the Mercalli-Cancani-Sieberg (MCS), Medvedev-Sponhouer-Karnik (MSK) and Mercalli Modified (MM). Eutizio Vittori, Eliana Esposito, Sabina Porfido and Alessandro M. Michetti produced a revised version, after (a) integration with the revised MM scale of Dengler and McPherson (1993) and (b) checking the scale against the description of coseismic ground effects and intensity assessments for several tens of historical and instrumental earthquakes in the world. The last version of the INQUA scale, to be presented during the INQUA Congress, is a joint contribution of the WG including new data, editing, comments and scientific discussion from Bagher and Jody Mohammadioun, Eugene Roghozin, Ruben Tatevossian, Aybars Gürpinar, Franck Audemard, Shmulik Marco, Jim McCalpin, Nils-Axel Mörner, and Valerio Comerci. Also, the newly revised MM scale for New Zealand (Hancox, Perrin and Dellow, 2002), kindly provided by Graeme Hancox, has been also taken into account in this last version.

The outstanding progress of paleoseismological and Quaternary geology research in the past decades makes available an entirely new knowledge for understanding the response of the physical environment to seismicity, thereby providing the basis for the proposed INQUA intensity scale.