  Earthquakes cannot be predicted with precision, but algorithms exist for
intermediate-term middle range prediction of main shocks above a pre-assigned
threshold, based on seismicity patterns. Few years ago, a first attempt was
made in the framework of project SISMA, funded by Italian Space Agency, to
jointly use seismological tools, like CN algorithm and scenario earthquakes,
and geodetic methods and techniques, like GPS and SAR monitoring, in order to
effectively constrain priority areas where to concentrate prevention and
seismic risk mitigation. We present a further development of integration of
seismological and geodetic information, clearly showing the contribution of
geodesy to the understanding and prediction of earthquakes. As a relevant
application, the seismic crisis that started in Central Italy in August 2016 is
considered in a retrospective analysis. Differently from the much more common
approach, here GPS data are not used to estimate the standard 2D velocity and
strain field in the area, but to reconstruct the velocity and strain pattern
along transects, which are properly oriented according to the a priori
information about the known tectonic setting. Overall, the analysis of the
available geodetic data indicates that it is possible to highlight the velocity
variation and the related strain accumulation in the area of Amatrice event,
within the area alarmed by CN since November 1st, 2012. The considered counter
examples, across CN alarmed and not-alarmed areas, do not show any comparable
spatial acceleration localized trend. Therefore, we show that the combined
analysis of the results of CN prediction algorithms, with those from the
processing of adequately dense and permanent GNSS network data, may allow the
routine highlight in advance of the strain accumulation. Thus it is possible to
significantly reduce the size of the CN alarmed areas.
