Macroseismic practice in the last twenty years has been strongly influenced by internet diffusion; both seismologists and citizens got fast, wide and direct access to data. The aim of the ESC Working Group Internet Macroseismology, active between 2008 and 2014, was to find a common basis for data collection from citizens and to reach homogeneous intensity quantification. Nevertheless, heterogeneity of data collection is still a widespread feature. Although today the experience of collection and analysis of internet macroseismic data has reached high levels in many European countries, the methods we use are still quite different and usually tailored to the needs of local customs and seismicity. During a recent Technical workshop on Internet Macroseismology (Ljubljana, November 2017) the need to harmonise methods and to simplify the data merging was clearly expressed. On one side there is the benefit of sharing ideas, news and information, on the other side there is the need to save the richness provided by different solutions adopted in European and Mediterranean countries. The safeguard of differences was a new element arisen in Ljubljana, suggesting to work more on intensity comparison and calibration.
The aim of this Working Group proposal is to promote ideas, exchange and cooperation among research groups in the frame of harmonization. Attention will be given to maintain the richness given by different European realities. The target is the integration and improvement of methods, especially for seismic events affecting more than one country, in view of a comprehensive European recent macroseismic intensity catalogue building. Such database creation is present also into the EPOS frame. Efforts will be given to create translation algorithms able to create homogeneous datasets, taking into account all local factors able to introduce systematic variations.
Potential participants, as expressed during the workshop in Ljubljana are seismologists from Austria, Belgium, Croatia, Finland, France, Germany, Italy, Norway, Slovakia, Portugal, Romania, Slovenia, Spain, Sweden, The Netherlands, UK, Malta and other. During this meeting a wide agreement was reached to cooperate into the direction of integration. The action of this common decision was to propose this Working Group and which was approved during the Plenary Meeting of ESC2018 in Malta.
A reasonable length of time for completion of main task is four years (’18-’22). In the first time period there will be an analysis of each different national internet macroseismic practice. It will follow an analysis to evidence common elements and a quantifications of differences of intensity values.
Products of the Working Group:
1) Report on analysis and comparison of the various currently active systems of internet macroseismology and individuation of common features in the countries database.
2) Definition of calibration parameters for database compatibility.
3) Application on selected multi-country events.
4) Proposal of a common protocol for macroseismic data acquisition.
Valerio de Rubeis, INGV