Van Noten, Koen ; de Rubeis, Valerio ; Tosi, Patrizia ; Sbarra, Paola ; Lecocq, Thomas

Poster presented at 6th Colloquium on historical earthquakes & paleoseismology studies, Han-sur-lesse, Belgium on 2018-10-24

Abstract: The practice of macroseismic investigation through internet inquiries is well established among numerous seismological institutions around the world, thanks to wide citizen participation. Although internet macroseismic data analysis has reached high levels in Europe, intensity methods adopted by each one of the national research institutes are still quite different and usually tailored to the needs of country-specific urban-structural settings and seismicity. This European fragmentation of data collection and analysis requires an urgent effort to harmonise macroseismic methods and to simplify data exchange. At the 36th General Assembly of the European Seismological Commission 2018 Meeting in Malta, a new ESC Working Group in Macroseismology (2018-2022) was composed aiming to improve macroseismic data exchange, to review national macroseismic practice and to encourage/facilitate cooperation among research groups for cross-border felt earthquakes and multiple source macroseismic data acquisition. Working Group products will be comprehensive European macroseismic intensity catalogue creation, framed within EPOS, and a definition of calibration parameters for database compatibility applied on multi-country and/or multi-institution data events. Instead of proposing a common, standardized procedure/questionnaire to produce an homogeneous dataset, we will develop an alternative approach consisting of respecting the differences among various strategies used to collect and analyse data, and applying a statistical evaluation of differences for the definition and implementation of corrective parameters. In this study this procedure is demonstrated on macroseismic data of several Italian earthquakes: i.e. the 2017 Mw 5.1 Amatrice, 2016 Mw 6.5 Norcia, 2016 Mw 6.0 Norcia, 2016 Mw 5.9 Visso, 2013 Mw 5.1 Fivizzano earthquakes, for which intensity data was provided by different institutions (INGV-HIST, EMSC, USGS-DYFI). Statistical methods were used to evaluate, in a quantitative way, the degree of agreement and differences between these three datasets, and the possibility to retrospectively merge data, in order to obtain more uniform and stable intensity data. Preliminary results show that merging these three datasets, without applying any correction, results in a near-field intensity underestimation (lack of proper damage estimation in all databases) and far-field intensity overestimation (lack of non-felt reports in USGS and EMSC databases).

Keyword(s): Macroseismic data ; Earthquakes ; Intensity