Mechanism of Deep-focus Earthquakes Anomalous Statistics

Analyzing the NEIC-data we have shown that the spatial deep-focus earthquake distribution in the Earth interior over the 1993-2006 is characterized by the clearly defined periodical fine discrete structure with period L=50 km, which is solely generated by earthquakes with magnitude M 3.9 to 5.3 and only on the convergent boundary of plates. To describe the formation of this structure we used the model of complex systems by A. Volynskii and S. Bazhenov. The key property of this model consists in the presence of a rigid coating on a soft substratum. It is shown that in subduction processes the role of a rigid coating plays the slab substance (lithosphere) and the upper mantle acts as a soft substratum. Within the framework of this model we have obtained the estimation of average values of stress in the upper mantle and Young's modulus for the oceanic slab (lithosphere) and upper mantle.Comment: 9 pages, 7 figure

Study of geomagnetic variations in Georgia and Establishment of anomaly nature of earthquake Precursors

Before strong earthquake magnetic precursors denoted by many authors, but must to say, that more of them don’t satisfy stern criterions. There are many examples of geomagnetic anomaly in Georgia too: a few weeks before earthquakes in Spitak, anomaly grows of low frequency geomagnetic pulsation amplitudes were fixed in Geophysics Laboratory of Dusheti. The, “When, where and how” earthquake prediction problem is not solved but is an actual problem for a long time. From 1989 researches on possible connection between geomagnetic variations and incoming earthquake started in INRNE. (Mavrodiev S. Cht., Thanassoulas C., Possible correlation between electromagnetic earth fields and future earthquake, INRNE-Bas, Seminar proceeding, July 23-27, 2001, Sofia, Bulgaria, ISBN 954-9820-05-X,2001). From February 2006 Ukraina was included in INRNE, BAS geomagnetic and Earthquake monitoring. From January 2009 Georgia with its Geomagnetic observatory of Dusheti was also included in INRNE, BAS. For estimation of the geomagnetic variations as a reliable precursor the specific time analysis was discovered for digital definition of Geomagnetic Quake and proposed a way for interval defined from the extremum of local tide variations [ S. Cht. Mavrodiev, 2001]. Georgian Geomagnetic stations can input important information for space dependences of precursor intensity as part of complex regional NETWORK of PrEqTiPlaMagInt 206 collaboration (Prediction Earthquake Time Place Magnitude Intensity). We introduce the primary work-up results of data received from the Dusheti Magnetic Observatory which was worked up for investigation of earthquake prediction on the basis of geomagnetic variations

Integrated transnational macroseismic data set for the strongest earthquakes of Vrancea (Romania).

A unique macroseismic data set for the strongest earthquakes occurring since 1940 in the Vrancea region is constructed by a thorough review of all available sources. Inconsistencies and errors in the reported data and in their use are also analysed. The final data set, which is free from inconsistencies, including those at the political borders, contains 9822 observations for the strong intermediate-depth earthquakes: 1940, Mw=7.7; 1977, Mw=7.4; 1986, Mw=7.1; 1990, May 30, Mw=6.9; 1990, May 31, Mw=6.4; and 2004, Mw = 6.0. This data set is available electronically as Supplementary data to the present paper. From the discrete macroseismic data, the continuous macroseismic field is generated using the methodology developed by Molchan et al. (2002). The procedure, along with the unconventional (smoothing method) modi\u2423ed polynomial \u2423ltering (MPF), uses the diffuse boundary (DB) method, which visualises the uncertainty in the isoseismal boundaries. The comparison of DBs with previous isoseismal maps supplies a good evaluation criterion of the reliability of earlier published maps. The produced isoseismals can be used not only for the formal comparison of the observed and theoretical isoseismals, but also for the retrieval of source properties and the assessment of local responses (Molchan et al., 2011)

Integrated unified mapping of the Vrancea macroseismic data for the CEI region.

The countries in Central and East Europe are periodically affected by strong earthquakes originating from Vrancea zone and significant seismic effects are recorded all over Romania, Moldova, Ukraine, Bulgaria, Serbia, Hungary, etc. Vrancea earthquakes are of practical and theoretical interest due to the social and economical influence on a vast territory. The main result of this study is the unique collection of intensity data for the Vrancea events of 1940, 1977, 1986, and 1990, which represents a real step forward that overcomes the inherent differences affecting the present-day maps, hampered by political boundaries. This is done adopting a unique modelling procedure and processing the available data in an integrated way. As a result, unified macroseismic maps of the relevant portion of the CEI region are produced using two new procedures, Modified Polynomial Filtering and Diffused Boundar