Introduction. The Moscow Regional Center (United Schmidt Institute of Physics of the Earth - UIPE) of the Global Seismic Hazard Assessment Program (GSHAP) was founded in 1992 after GSHAP Technical Planning Meeting in Rome. However, investigations adequate to GSHAP started in former USSR (CIS, now) in 1991, directed by the UIPE (Prof. V.I.Ulomov, Coordinator). The studied territory of Northern Eurasia (GSHAP Region 7) covers the area 30-90° N, 20° E-170° W degrees and includes whole territory of Russia and other republics of former USSR, and also contiguous seismically active areas. The total number of participants of these investigations were more than 30 research institutes of Russian Federation and other CIS-countries.

Beginning from 1993 the GSHAP Regional Centers for Northern Eurasia (the UIPE of Moscow) and for the Middle East (the IIEES of Tehran) have joined efforts in the Crimea-Caucasus-Kopetdagh test area. It has been proposed by GSHAP and jointly supported by IASPEI/ESC/INTAS, and includes the seismological institutions from the Caucasian republics, Russia, Ukraine, Turkmenistan, Italy, Czech, Turkey, Iran and others countries. Workshops have been held in Tehran (1/1993), Moscow (9/1993), Ashgabad (10/1994), Tehran (5/1995), Yerevan (7/1996) and Tbilisi (7/1997). The Caucasus activities are supported by INTAS under 94-1644. The Yerevan WG (7/1996) was supported by NATO-ARW. The Moscow GSHAP Regional Center and Beijing Regional Center for the Central-Southern Asia (the SSB of Beijing) have joined efforts in the Central Asia, Mongolia and Far Eastern regions. Workshops have been held in Beijing (4/1993 and 10/1994) and in Moscow (4/1996 and 9/1997). The similar international working meeting on creation of the map of earthquake source zones of Central Asia (as the fragment of the Northern Eurasia GSHAP Region 7) have been held in Bishkek (9/1995). It was organized by UIPE and Institute of seismology of Academy of science of Kyrgyz Republic by financial support of Russia. In this meeting the representatives from Uzbekistan, Kyrgyzstan, Russia, Kazachstan and Tadzhikictan have accepted participation.

Methodology. The methodology for seismic hazard zoning developed in UIPE is based on the two-stage principle implying the creation of two mutually related probable models: a model of source zones (MSZ) and a model of seismic effect (MSE). This methodology includes the technology of operations with 2D and 3D source zones and adequate reflects the nature of seismicity. The denotation of this method is «Earthquake Adequate Sources Technology - EAST-97» and based on lattice regularization and on the conception of: (a) fractal structural-dynamic unity of the medium and the seismic processes in it; (b) upper threshold for magnitude stipulated by geoblock sizes, hardness and intensity of their interactions; (c) deterministic-probabilistic approach to all input and output data.

According to the program were created several working groups coordinated by following Russian scientists:
Methodology of Seismic Hazard Assessment - V.I.Ulomov and A.A.Gusev;
Earthquake Catalogues and Data Base - N.V.Kondorskaya and V.I.Ulomov;
Neotectonics - A.F.Grachev;
Active faults - V.G.Trifonov and A.I.Kozhurin;
Seismicity and Seismic Regime - V.I.Ulomov and L.S.Shumilina;
Seismogeological Taxonomy - N.V.Shebalin and V.G.Trifonov;
Earthquake Source Zones - V.I.Ulomov and V.G.Trifonov;
Potential earthquake sources - G.I.Reissner and E.A.Rogozhin;
Strong Ground Motion Attenuation - A.A.Gusev and L.S.Shumilina;
Software for Hazard Calculation - A.A.Gusev and V.M.Pavlov;
Seismic Hazard Computation and Mapping - V.I.Ulomov and L.S.Shumilina;
Geographical Information System Implementation - V.I.Ulomov and S.Anderzhznov.

Geodynamics and Seismicity. The seismicity of Northern Eurasia stipulated by intense geodynamic interaction between eight large lithosphere plates: European, Asian, Arabian, Indian, Chinese, Pacific Ocean, Okhotsk Sea and Northern-American. The structural and historical regularities of tectonics and geodynamics established over such the vast territory of Northern Eurasia allow to consider them as planetary system. They are expressed in heterogeneity of recent tectonic structure, starting with the lithosphere and terminating in regional subdivisions. It is necessary to do the investigations of the tectonic objects of various hierarchical rank clearly distinguishing their static and dynamic characteristics. The Earth crust of platforms characterized by 40 - 50 km thickness, but in the continental orogenic belts Moho discontinuity situated on the depth 60 km and more. The orderliness exhibited by the regional structure of global seismicity shows that a close connection exists between intracontinental seismic regions and relict subduction zones. The Northern Eurasia includes the platform territories (East-European or Russian, West-Siberian and Siberian) with very low and diffuse seismicity, and several orogenic regions with higher activity (Iran-Caucasus-Anatolia, Central Asia, Altay-Sayany-Baikal region etc.) and legible structured seismicity. Kuril-Kamchatka subduction zone is most geodynamic and seismic active region with depth of earthquake hypocenters 600 km and more. The Carpathians and Pamir-Hyndukush relict subduction zones produce intermediate focus earthquakes with depth of hypocenters till to 150 and 300 kms respectively.

Basic earthquake catalogue of Northern Eurasia adopted for the GSHAP Project is the «Specialized Earthquake Catalogue of Northern Eurasia» (SECNE), which was created under the National Research Program «Seismicity and Seismic Zoning of Northern Eurasia». The SECNE includes more than 30 thousand events with moment magnitude Mwі 4.5 from ancient times until 1995. Specific attention was devoted to the reconciliation of differences and coordination of parameters of earthquakes occurring on the adjacent territories. It is essential for identification of earthquake-generating features and for the assessment of their seismic potential to map earthquake sources in accordance with their dimensions and orientations rather than point epicenters. Earthquake sources of М=>7 (М=>6.8) are shown to the realistic size on the map scale as ellipses having long L and short W axes according to formulas logL = 0.6M – 2.5; logW = 0.15M + 0.42 and for interval 4.0<=M<=6.5 - as circles of decreasing diameter.

According to Regionalization of Northern Eurasia the four main sectors (East Europe; Central Asia; Central Siberia; East Asia) include the seventeen seismotectonic regions characterized by specifically seismic regime. The interval 4.0<=M<=6.0 of earthquakes in each regions of Northern Eurasia characterize by exponential frequency-magnitude relationship, but the nonexponential distribution of events is the attribute of magnitude range M=>6.5. Earlier this factor was ignored by compilers of former seismic zoning maps and in result, in particular, the return period of large earthquakes in 3-5 and more times was decreased.

Earthquake Source Zones. According to developed in UIPE the Lineament-Domain-Focal (LDF) model of seismic source zones (SSZ) a main structural unit of global seismicity - is a region. Each region include the seismic structure of three types: lineaments, domains and potential earthquake sources. Seismic lineaments constitute the frame of the SSZ model and show the axes of earthquake-generating features. The sources do not settle down strictly lengthwise of lineaments and deviate them in both sides on distances depended from magnitude of earthquakes, generated by them. Domains are represented as quasi-homogeneous seismotectonic areas in which impossible to identify whichever lineaments. Potential earthquake foci identified by various methods are mostly confined to lineaments.

Seismic source zones are classified, similarly to earthquakes, according to the following magnitude intervals: M=8.5+-0.2; 8.0+-0.2; 7.5+-0.2; 7.0+-0.2; 6.5+-0.2; 6.0+-0.2; 5.5+-0.2; 5.0+-0.2; 4.5+-0.2; 4.0+-0.2. The regional seismic rates are adequate distributed between all structures of various ranks: events with М=>6.0 belong to lineaments proportionally to their common length and potential sources, while those of М<=5.5 to domains. 

In all, 580 lineaments with M=>6.0 (including more than 1000 their short segments), 442 domains with M<=5.5 and 11 potential foci with M=>7.0 were specified on the territory of the Northern Eurasia.

Strong Ground Motion. The Intensity-Distance-Magnitude relationship I(D, Mw) is simulated using a simple theoretical model calibrated using observed macroseismic data for the whole Northern Eurasia. In the vicinity of the source the model describes consistently the amplitude saturation around a fault. The elongated shape of first isoseismals is modeled automatically. The scatter of I(D, Mw) relationship is produced by variations of source radiation capability at a given Mw, and by variation in propagation path and near-receiver structure (ground) effects. The sources are modeled as two normal distributions with zero mean and standard deviations of sigma 0.5 and 0.8 respectively. These values were estimated approximately from actual macroseismic data.

Seismic Hazard Computation and Zoning. The method developed in UIPE follows the usual lines of Yu.V.Riznichenko (1965) and C.A.Cornell (1968). The technique includes however several improvements as compared to typical techniques:
Finite earthquake sources are modeled as 2D sources (vertical and inclined rectangular with L and H sides stipulated by seismic moment Mo) of high-frequency (0.5-10 Hz) seismic waves; an approximate model of incoherent wave field around a finite source is used that adequately describes the near-source saturation effects; intensity values are determined based on Arias intensity estimates (Arias, 1970; Gusev, 1984).
The numerical technique used is the Monte-Carlo modeling using simulated random earthquake catalogue (approach of A.Shapira, 1983).

For the Seismic Hazard Map of the Northern Eurasia in the terms a peak ground accelerations (PGA) it was agreed to convert intensity to PGA in m/s/s using the empirical relationship: logA(m/s/s)=0.333 I(MSK) – 2.222. It has allowed correctly to take into account effect from extended seismic sources. The calculation grid for the PGA with 10% probability of exceeding in 50 years is 25 km x 25 km for whole Northern Eurasia. This PGA map was created on the base of the complete set of seismic zoning maps (10%, 5% and 1% probability with 10% probability of exceeding in 50 years) accepted now in Russia as the normative documents for Building Code in application to construction of different categories of significance and life (A, B, C). As has shown the analysis of the created PGA map, it largely more correctly reflects natural conditions in comparison with all previous maps of seismic zoning.

The more detailed outcomes of Moscow GSHAP Regional Center can be found on the Internet:

http: //seismo.ethz.ch/hazard/gshap/nordasia

Bibliography.

Global Seismic Hazard Assessment Program, Annali di Geofisica, Spec. issue: Technical Planning Volume of the ILP`s, 1993, XXXVI, 3–4, 257p.

Ulomov, V.I., Structural and dynamical regularity of Eurasia intracontinental seismicity and some aspects of seismic hazard prediction, XXIV General ESC Assembly, 1994 September 19-24, Proceedings and Active Report 1992-1994, vol. 1, Athens, Greece, pp.271-281.

Shebalin, N.V., Ulomov, V.I., Tatevossian, R.E., Trifonov, V.G., Ioffe, A.I., Kozhurin, A.I., Unified Seismogeological Taxonomy of the Northern Eurasia, IUGG-Abstracts, Boulder, U.S.A., 1995, SB21C-14.

Ulomov, V.I., Seismic hazard assessment in Northern Eurasia, IUGG-Abstracts, Boulder, U.S.A., 1995, SB51D-3, pp.B-404.

Ulomov, V.I., Non-linear dynamics of fractal geostructure and fractal lattice model of the seismogenesis, Abstracts of ESC, Reykjavik, Iceland, 1996, E1.22, p.71.

Ulomov, V.I., On the identification and seismological parameterization of earthquake source zones, The Caucasus and adjacent area, Historical and Prehistorical Earthquakes in the Caucasus (edited by Domenico Giardini and Sergiei Balassanian), NATO ASI, Series 2: Environment – Vol. 28, ILP Publication n.333, Kluwer Academic Publishers, Dordrecht / Boston / London, 1997, pp.503-522.

Ulomov, V.I., Focal Zones of Earthquakes Modeled in Terms of the Lattice Regularization, Izvestiya, Physics of the Solid Earth, 1998, vol. 34, no. 9, pp.717-733.