Static stress drop as determined from geodetic strain rates and statistical 1 seismicity

9 Two critical items in the energetic budget of a seismic province are the strain rate, which 10 is measured geodetically on the Earth’s surface, and the yearly number of earthquakes 11 exceeding a given magnitude. Our study is based on one of the most complete and recent 12 seismic catalogues of Italian earthquakes and on the strain rate map implied by a multi13 year velocity solution for permanent GPS stations. For each of 36 homogeneous seismic 14 zones we use the appropriate Gutenberg Richter relation, which is based on the seismicity 15 catalogue, to estimate a seismic strain rate, which is the strain rate associated with the 16 mechanical work due to a co-seismic displacement. We show that, for each seismic zone, 17 the volume storing most of the elastic energy associated with the long-term deformation, 18 and hence the seismic strain rate, is inversely proportional to the static stress drop. The 19 GPS-derived strain rate for each seismic zone limits the corresponding seismic strain rate, 20 and an upper bound for the average stress drop is estimated. We show that the implied 21