History of Science and Engineering Annotation << Back ON HYDROGEODYNAMIC PRECURSOR OF EARTHQUAKES S.M. Saprygin, M.V. Senachin, V.N. Senachin The paper discusses the experimental data which showed for the fi rst time the shadow zone of the hydrogeodynamic precursor of shallow (10–50 km) earthquakes in Sakhalin and Kurile Islands. On the plot «depth-epicentral distance» the shadow zone occupies the sector between 0–20° relative to the Earth′s surface. Its origination is related to the effect of strengthening of rocks under compression which is generated by crustal earthquakes (in this case the source can occupy the lateral position relative to the water-bearing horizon). Piezometric effect during lateral compression is observed when deformations are one-two orders of magnitude larger than produced by earthguake precursor and depends on the bed jointing which regulates permeability of the water-beating horizon. Shadow zone is presented for crustal carthquakes of the Pacifi c belt and it can be neutralized by using some other geophysical observations. Keywords: hydrogeodynamic precursor of earthquakes; water- bearing horizon; piezometric well. Contacts: E-mail: lordvader2014@mail.ru Pp. 089-094.