The recent earthquakes in L’Aquila (Italy)
and in Japan have dramatically emphasized the problem
of natural disasters and their correct forecasting. One
of the aims of the research community is to find a
possible and reliable forecasting method, considering all
the available technologies and tools. Starting from the
recently developed research concerning this topic and
considering that the number of GPS reference stations
around the world is continuously increasing, this study
is an attempt to investigate whether it is possible to use
GPS data in order to enhance earthquake forecasting. In
some cases, ionospheric activity level increases just before
to an earthquake event and shows a different behaviour
5–10 days before the event, when the seismic event has
a magnitude greater than 4–4.5 degrees. Considering the
GPS data from the reference stations located around the
L’Aquila area (Italy), an analysis of the daily variations of
the ionospheric signal delay has been carried out in order
to evaluate a possible correlation between seismic events
and unexpected variations of ionospheric activities. Many
different scenarios have been tested, in particular considering
the elevation angles, the visibility lengths and the time of
day (morning, afternoon or night) of the satellites. In this
paper, the contribution of the ionospheric impact has been
shown: a realistic correlation between ionospheric delay and
earthquake can be seen about one week before the seismic
event.