Results

Aftershock Catalogs for seismic regions of Russia
We made detailed catalogs of mainshocks and their aftershocks for seismic regions of Russia:

Mainshocks and their afetrshocks were marked using software by V.B. Smirnov which implements declustering method of Molchan and Dmitrieva.

Data for Kamchtka and Kuril Islands taken from Catalog of Earthquakes for Kamchatka and Commander Islands Catalog of Earthquakes for Kamchatka and Commander Islands (1962 — present time), made by Kamchatka Branch of the Federal Research Center of the Unified Geophysical Survey of the Russian Academy of Sciences

Datа for Lake Baikal and Transbaikalia takern from Main Catalog made by Baikal Branch of the Federal Research Center of the Unified Geophysical Survey of the Russian Academy of Sciences

Data for Caucasus taken from Earthquake catalog of Caucasus since historic times till the present made by Gabsatarova I.P. and Borisov P.A. from the Federal Research Center of the Unified Geophysical Survey of the Russian Academy of Sciences and supprted by this project.

ESTIMATING AN AREA WHERE STRONG AFTERSHOCKS ARE EXPECTED

S.V. Baranov, P.N. Shebalin

Methodology for forecasting space area in which strong repeated shocks or aftershocks are expected was developed. We formulated a problem for estimating an area of the future strong aftershocks based on the data for the first 12 hours after the mainshock. Existing methodologies for separating aftershocks cannot be applied to solve this problem as they either based on analysis of distribution of epicenters of finished aftershock process or provides rough estimate. By means of specially developed tests for estimating the forecast quality we quantitatively compared a lot of variants. The variants were both main known models of aftershock areas and the suggested modifications which take into account the results of modern researches devoted to dynamics of aftershock process. As a result, we chose an optimal model which gives the best estimation according to the quantitative tests for more than 120 aftershock series due to M6.5+ earthquakes from over the world. The model can be used in centers of seismic monitoring for forecasting space distribution of aftershock activity after strong earthquake based on preliminary processed data. In press (Izvestiya, Physics of the Solid Earth). After the paper is published it’ll be available in the Publication section.

Based on the optimal models we developed web based software for forecasting space distribution of strong aftershock in quasi real time. The forecast is available in this site for registered users.

EXPRESS ESTIMATING STRONG AFTERSHOCK HAZARD

P. N. Shebalin, S.V. Baranov

Methods for estimating strong aftershock hazard for Kamchatka and Kuril Islands using date for the first 12 hours after the mainshock: aftershock number, expectation time, maximum magnitude. The suggested methods tested using earthquake catalog for 1968 – Aug. 2016 collected by Kamсhatka Branch of the Federal Research Center of the Unified Geophysical Survey of Russian Academy of Sciences. The catalog was declustered for marking out mainshock and their aftershocks. Based on the joint use Gutenberg-Richter and Omori law we showed that the aftershock number in non-overlapping time intervals are in proportion and the proportionality factor is independent of the cut-off magnitude. By means of this feature we calculated the
proportionality factors for estimating aftershock number with the magnitude greater than the given threshold based in the data for the first 12 hours after the mainshock. We provided simply memorable formulas for estimating the aftershock number expected during 5 days and a month after the mainshock. We obtained empirical relations for estimating the biggest aftershock magnitude expected during a year after the mainshock and time of the last aftershock with M5.2+ as well. In press (Volcanology and Seismology). After the paper is published it’ll be available in the Publication section.