Preface : “ Improving seismic networks performances : from site selection to data integration ” ( EGU 2015 SM 1 . 2 / GI 1 . 5 session )

The number and quality of seismic stations and networks in Europe continually improves, nevertheless there is always scope to optimize their performance. In this EGU2015 SM1.2/GI1.5 session we welcomed contributions from all aspects of seismic network installation, operation and management. This includes site selection; equipment testing and installation; planning and implementing communication paths; policies for redundancy in data acquisition, processing and archiving; and integration of different data sets including GPS and OBS.


Introduction
The history of seismic networks sessions at European Geosciences Union (EGU) General Assemblies started in 2010 with the SM1.3 "Seismic Centers Data Acquisition" session (Pesaresi, 2011), where the Convener Damiano Pesaresi supported by the Orfeus Data Center (ODC) Director Co-Convener Reinoud Sleeman chaired a session of 7 oral and 16 posters.A similar session was later the same year held at the XXXII European Seismological Commission (ESC) General Assembly: "SD1, 3 Seismic centers data acquisition", conveners D. Pesaresi and R. Sleeman, with 15 oral presentations.
The history continued in 2011 with the EGU2011 SM1.3/G3.8/GD3.7/GI-19/TS8.7 "Improving seismic networks performances: from site selection to data integration" session (EGU2011 SM1.3/G3.8/GD3.7/GI-19/TS8.7 Improving seismic networks performances: from site selection to data integration, 2011) where the Convener Damiano Pesaresi supported by the Co-Conveners John Clinton and Robert Busby chaired a session of 9 oral and 20 posters, in 2012 with the EGU2012 SM1.3/GI1.7 "Improving seismic networks performances: from site selection to data integration" session (Pesaresi and Vernon, 2013) where the Convener Damiano Pesaresi supported by the Co-Convener Frank Vernon chaired a session of 6 oral and 22 posters, and in 2013 with the SM1.4/GI1.6 "Improving seismic networks performances: from site selection to data integration" session (Pesaresi and Busby, 2013) where the Convener Damiano Pesaresi supported by the Co-Convener Robert Busby chaired a session of 6 oral and 13 posters.
The 39 presentations come from 16 countries (USA, Norway, Germany, France, Canada, Italy, Poland, Finland, Taiwan, Austria, Romania, Malta, Spain, Algeria, Switzerland, UK) from 4 different continents (North America, Europe, Asia, and Africa), which well fits the goals of the European Geosciences Union.
Solicited presentations in this session were:   Monika Sobiesiak, and Torsten Dahm (Grigoli et al., 2014); iii. "Detecting and locating teleseismic events with using USArray as a big antenna" by Lise

Conclusions
The quality and quantity of presentations made at the EGU2014 SM1.2/GI3.7 session well satisfied the expectations of the Convener and Co-Conveners, and well fitted the goals of the European Geosciences Union.The increasing number of presentations at such yearly seismic networks sessions encourage the conveners that the path they followed in organizing such sessions is a valid one, and that there is need in the seismological community worldwide to present and discuss different solutions to common problems in running seismic networks.
VI. "Significant breakthroughs in monitoring networks of the volcanological and seismological French observatories", by A. A. Anglade, A. L. Lemarchand, and J. M. S. Saurel; VII."How to create a very-low cost, very-low-power, credit-card-sized and real-time ready datalogger", by M. Bès de Berc, M. Grunberg, and F. Engels; VIII."