[S02-6] New directions in anthropogenic seismicity studies II

[S02-6-01] Discrimination of induced seismicity component in the seismicity of Sakhalin offshore hydrocarbon fields

^○Sergey Turuntaev^{1, 2}, Alexey Konovalov³, Andrey Stepnov³, Elena Slinkova¹, Anna Gubanova² (1.Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, Russia, 2.Moscow Institute of Physics and Technology, Moscow, Russia, 3.Institute of Marine Geology & Geophysics of FEB RAS, Yuzhno-Sakhalinsk, Russia)

Sakhalin Island offshore hydrocarbon fields (Russia) are located in the region of high natural seismic activity. That causes a concern on the possibility to trigger a catastrophic earthquake by the hydrocarbon field developments in this region. The concern is backed by probably triggering nature of the catastrophic Neftegorsk earthquake in 1995 (Mw=7.2). That is why a local seismic network was installed along the eastern shore of Northern Sakhalin in 2006 prior to active phase of the offshore hydrocarbon field developments. The results of analysis of the seismic activity registered by this seismic network are considered in comparison with the natural seismicity registered by the regional seismic network in 1950-1990. It was found that while there are no proved sings of the seismic activity increase due to oil and gas production in the controlled region, some changes in the seismic regime take place: b-value became a bit higher than it was before; the distribution of the time intervals between successive events became of the Weibull type with the form parameter less than 1; local maximums of the seismic activity spatial distribution became closer to the boundaries of the developed hydrocarbon fields; the correlation dimension calculated by Grasberger-Procaccia method became smaller. All these changes are typical for induced seismicity.