Contents

Seismicity and Geodynamics
V.S.Imaev, L.P.Imaeva, B.M.Koz’min, K.Mackey and К.Fujita. Seismotectonic processes along the boundary of litospheric plates of Northeast Asia and Alaska    3
Yu.F.Malyshev. Deep structure, geodynamics and seismicity in area of conjunction of the Central-Asian and Pacific Mobile Belts    18
V.P.Vazhenin. Some principles of seismic zoning and paleoseismogeology (as exemplified by Russia’s Northeast)    28
S.V.Gorkusha, A.O.Morin Seismicity, block divisibility and tectonic stress in Russia’s Far East South    42
V.A.Bormotov, A.A.Voitenok. Regularaties of earthquake migration in Priamurie    51
V.Ye.Kuznetsov.Deep structure and modern geodynamics of Priamurie    61
R.M. Semenov.The Neftegorsk (Russia) and the Haichen (China) earthquakes: pre-seismic geological conditions, surface rupturing, and the problems of prediction    68
T. I.Podgornaya, I.I.Sats.Forecast of seismicity changes in the explored areas as a result of manmade influence in the Khabarovsk territory     79
A.V.Vikulin.Natural hazards to Nothern Kamchatka     85
The Earth's Crust and Upper Mantle Structure
M.N Luneva.The Earth's crust structure and seismic wave dynamics    93
R.G.Kulinich, L.A.Maslov, G.Z.Gilmanova, O.S.Komova.Density model and crust stress in the northern part of the Sea of Japan    108
T.K.Zlobin, S.A.Kostyukevich, L.M.Zlobina.The Earth’s crust structure of the Middle Kurils from seismic modeling    115
V.B.Kaplun.Preliminary results of deep magnetotelluric soundings carried out along the Obluchie - Lake Gassi profile (Khabarovsk Territory)     122
Process Physics and Forerunners of the Earthquakes
L.I.Morozova.Meteorological satellite images as the bearers of information on seismicity    136
V.G.Bykov. Mechanism of soliton formation due to stick -slip in the crustal fault    141
V.A.Akhmadulin. Electromagnetic forerunners of the earthquakes     147

V.S.Imaev, L.P.Imaeva, B.M.Koz’min, K.Mackey and К.Fujita
Seismotectonic processes along the boundary of litospheric plates
of Northeast Asia and Alaska
The paper presents information on comprehensive study of seismicity, seismotectonics, active faults and stress features of the Earth’s crust along the North American, Eurasian, Sea of Okhotsk and Pacific plates boundary from Greenland through the Arctic Ocean and Northeast Asia to Alaska. Frequent change of geodynamic regimes of the Earth’s crust is established: its extension (Gakkel Ridge), transitional zone (mixed field of tectonic stresses in the Laptev Sea shelf and on its coast), slide and left strike-slip faults as a result of north-eastern compression (Chersky Range), slide and right strike-slip faults (from the Komandorskiye Islands to the Aleutian Islands), and frontal compression (Aleutian arc). The above boundary is accompanied by the Laptev Sea and Bering Sea microplates or blocks, which were formed between the interacting plates-giants. At the rear of the Bering Sea block the most recent structure of the Bering Sea rift is distinguished.

Yu.F.Malyshev
Deep structure, geodynamics and seismicity in the area of conjunction
of the Central-Asian and Pacific Mobile Belts
The connection is considered between seismic belts, zones, and areas with deep structure and geodynamics in the area of conjunction of the Central-Asian and Pacific tectonic belts. Deep sections show location of earthquake foci at the upper boundary of the low velocity layers and at the boundary of the layers with different density of rocks in the middle and upper crust. Correlation of seismic belts, zones and areas with the uprise of the upper boundary of the asthenosphere and the anomalous low-density mantle is revealed, in rare cases, with the change of the gradient of thickness of the lithosphere and the high-density mantle. The spatial inheritance of the former geological structural plan by the elements of seismicity takes places but is not often displayed in the region. Strike-slips caused by compression and extension, including the blocks of rotation, less frequently, the faults of regmatic origin, play a great role in earthquake occurrence. The key point of the problem of connection of seismicity with deep structure and geodynamics is to reveal the correlation between the paleo- and modern geodynamic models.

V.P.Vazhenin
Some principles of seismic zoning and paleoseismogeology (as exemplified by Russia’s Northeast)
The present author examines the fundamental principles of paleoseismogeology which are used as a basis for seismic zoning. The author made a retrospective study of different standard maps of seismic zoning which cover the southeastern Chersky Seismic Belt including the Magadan Region. According to the results obtained, a non-declared “precedent principle” has been established, which is obviously used for seismic zoning purposes to predict only the earthquakes of the same intensity as the previous ones, and those which occurred only in places where such events had been recorded before. The prediction value of the standard maps published earlier was assessed in comparison with the subsequent seismic events. The prediction error for the earthquakes of 7-9 intensity points was established as exceeding 80%, i.e., the average under-estimation of seismicity was 1 or maximum 2 intensity points per one seismic event. The precedent principle of seismic zoning represents a well-known principle of inheritance pertaining to seismicity as well as to any other “long-living” geological process. Hence, it follows that the gross errors in predicting destructive earthquakes throughout the former USSR and Russia over the last few decades have been due to an insufficient “extent” of the destructive earthquake precedent used, whereas the precedent principle itself is quite valid. The lack of the destructive earthquake precedent is explained by the fact that the destructive earthquakes are scarce and repeat irregularly, and moreover, the duration of their observation is quite insufficient. In the author’s opinion, the time span of retrospective observation of the seismicity destructive constituent can be significantly increased by up to 10,000 years by a wide use of available paleoseismogeological data for seismic zoning. According to this approach, paleoseismic dislocations, which are geological and geomorphological evidence of the old destructive earthquakes there, are qualified as natural paleoseismograms having the same accuracy of most determined parameters as the instrumentally obtained seismograms.A new paleoseismogeological method developed and widely tested by the author provides a much greater efficiency of an overall paleoseismogeological study of seismic areas in comparison with the known methods. The validity and accuracy of paleoseismogeological data are testified by the principles of actualism, of dynamic correspondence of gravitational paleoseismic dislocations to their formation conditions, and of correspondence of correlative accumulative and denudation seismicity-related topographic forms. The above-mentioned principles and the new paleoseismogeological method served as a basis for making a chart of destructive earthquake zones throughout the Chersky Belt. The validity of this chart was proved by the Gulf of Shelikhov Earthquake in 1996, which had an intensity of 8 points and had not been predicted by the standard seismic zoning maps.

S.V.Gorkusha, A.O.Morin
Seismicity, block divisibility and tectonic stress in Russia’s Far East South
Based on a set of geological-geophysical data and also on location of earthquake epicenters, the Far East South lithosphere is divided into a number of blocks similar as to seismicity and their geologic structure. A number of aseismic blocks is distinguished; they are characterized by the maximum amplitudes of vertical crustal movements, the intensive minima of the gravity field, and by increased crustal thickness, with seismic activity being concentrated on the periphery and in the zones separating the above blocks. Two structural stages are discerned within the lithosphere with a different number of blocks distinguished and seismicity values observed. The depth of stage interface reaches about 15 km. For the earthquakes with the known focal mechanisms the parameters of seismogenerating stress are computed. The data on the extended equiseismotectonic zones distinguished within the regions where the stress state and stress orientation are constant can be considered as the principal ones. Four equiseismotectonic zones are singled out in the study area. In the Turansky zone sublatitudinal extension is seismogenerating , while in the Selemjinsky zone, close to the north-eastward uniaxial compression, and in the Zeysky zone, seismogenerating is sublatitudinal compression. In the Tatar Strait zone the stress is close to pure shear, with suborizontal north-westward extension. The chains of earthquakes with M>4 are contouring the zones with different tectonic stress.

V.A.Bormotov, A.A.Voitenok
Regularities of earthquake migration in Priamurie
Migration of earthquakes in East Priamurie in the area of the Tan-Lu -Kursky regional seismoactive fault zone is studied. For the analysis seismological data obtained in the area elongated from the Liaodong Gulf to the north-eastern coast of the island of Sakhalin were used. According to the data obtained in the current century, a series of regional chains of earthquakes is discerned in the zone characterized by the rate of migration as high as 100-110 km/year. Explanation is suggested as to the process of preparation of the above earthquakes and the grounds are also given concerning the north-eastward continuation of the Tan-Lu-Kursky seismogenic fault zone to the northern part of the island of Sakhalin.

 V.Ye.Kuznetsov
Deep structure and modern geodynamics of Priamurie
For the first time have been localized two arcuate seismo-lineament zones on the basis of the structure of the earthquake epicentral field of Priamurie. Under consideration are their structural-genetic relationships with the peculiarities of the deep structure of the territory from the data obtained by the method of the converted waves. A model is suggested of the distinguished lineaments as areas of concentration of stress and related to them rupture dislocations as a result of lateral displacement of the subhorizontal lithospheric slab along the deep crust-mantle shear.

R.M. Semenov
The Neftegorsk (Russia) and the Haichen (China) earthquakes: pre-seismic geological conditions, surface rupturing, and the problems of prediction
A number of strong seismic shocks happen on the globe annually. The Neftegorsk earthquake that stroke the island of Sakhalin (Russia) in May 1995, and the 1975 Haichen earthquake in China are among the strongest events with catastrophic consequences. The latter can be cited as a classical example, though so far being unique in the world, of a successfully predicted hazard, whereas the former event had never been expected before, neither its geological conditions nor the energy it could release. A comparative study of pre-seismic geological and tectonic conditions and surface rupturing produced by the two earthquakes, along with the analysis of precursors to the Haichen earthquake, has led to a conclusion that the location and strength of the Neftegorsk earthquake could have been predicted.

T. I.Podgornaya, I.I.Sats
Forecast of seismicity changes in the explored areas as a result of manmade influence in the Khabarovsk Territory
Changes of geological environmental conditions under the purposeful and spontaneous manmade influence in the Far East is manifested in aggravation of seismic danger. The factors which increase or reduce seismic danger are exemplified by Birobidzhan situated in the zone of seismic force 7. Improvement of seismic conditions and reduction of seismic danger is expected in case of prevalence of large inert disintegrated rock formations in the geological section as well as limited distribution of sensor rocks. Deterioration of seismic conditions and increase of seismic danger is more probable in case of the presence of sensor manmade deposits, argillaceous and sandy rocks of great thickness, irrigated thick units composed of gravel and pebbles, a high level of subsoil water, and tectonic zones. A possibility of seismic impact intensity increases by 1-3 points on the seismic force scale due to resonance phenomena and a high degree of effect of dangerous natural and manmade geological processes. For the forecast of seismic danger changes in the urban territories of Khabarovsk and Komsomolsk it is advisable to use available geo-ecological information and large-scale maps reflecting the current conditions of geological environment and the character of manmade influence. The forecast of seismicity changes on the explored territories will enable us to solve a number of very important tasks for the region’s stable development: rational use of urban land, increase of seismic resistance of buildings, revealing of stable sites for placing large and ecologically dangerous targets in seismic regions, elaboration of specific measures of population protection, softening of consequences of earthquakes and attendant natural and manmade catastrophes.

A.V.Vikulin
Natural hazards to Nothern Kamchatka
The territory of Northern Kamchatka has been a sufficiently safe region. However, the Khailino’s earthquake of March 8, 1991 has shown, that the current seismic zoning map (1978) “made a mistake” by 2-3 intensity levels according to the 12-intensity scale. As a result of integrated investigation (1992-1995) in the Koryak region a network of seismic stations and a new seismic zoning map have been made. It is inferred that the Bering Sea coastal line is tsunami-prone, and has been eroded at a speed of one meter per year during the last decades. It is noted that the determination of the amount of an apparent hazard to the coastal territory located in a seismic zone is necessary to work out a new concept that would allow taking into account all components of natural hazards.

M.N Luneva
The Earth's crust structure and seismic wave dynamics
Based on the contemporary viewpoint as to variation of physical and mechanical state and composition of geomaterial with depth within the Earth’s crust, and with the account of deep drilling and geophysical data, the model of the Earth’s crust is considered to understand better the realistic models for the mathematical modeling of different seismic effects. Various types of boundary conditions between media were analyzed relative to the dynamic properties of reflected/transmitted waves. It is shown that the anomalous behaviour of seismic wave dynamics is predominantly caused by the boundaries with a non-rigid contact between the media and also by contrast of coefficients of porosity, cracking or anisotropy of the contacting media.

R.G.Kulinich, L.A.Maslov, G.Z.Gilmanova, O.S.Komova
Density model and crust stress in the northern part of the Sea of Japan
On the basis of new geophysical data, density modeling and calculation of the geodynamic conditions of the Earth’s crust in the NW part of the Sea of Japan were carried out. The Earth’s crust zonation for genetic types was specified. The structure of the Siberian Seamount and the tectonic fracture zone separating it from the continent during the Sea of Japan Basin opening was specified. Areas with various modes of geodynamic stress and possible movement of the crust-mantle substance were defined. Descending movement of the substance takes place on the continental shelf’s edge and slope of Primorye. The substance flow moving from the continent to the Siberian Seamount is additionally revealed, which corresponds to a proceeding mode of crust stretching in this area. Now the Siberian Seamount is actively rising. Deep-water Japan Basin is characterized by a descending movement of crust-mantle masses. An ascending movement and some lateral motion of crust-mantle substance to the Japan Basin prevail in the Yamato Rise area. This may be regarded as an attribute of the Yamato Rise, moving onto the deep-water basin, and the beginning of its one-sided closure.

T.K.Zlobin, S.A.Kostyukevich, L.M.Zlobina
The Earth’s crust structure of the Middle Kurils from seismic modeling
Seismic modeling was made of the Earth’s crust structure of the Middle Kurils on the basis of deep seismic sounding data obtained on the 240-km Urup-Rasshua profile. The profile was made by the method of the inverse travel-time curve. Explosions were performed in the sea every 4 miles, stations were installed on the islands every 30-80 km. The modeling was carried out under a set of programs “Seismod” by linearization methods. As a result, 5 different-structure blocks were distinguished in the structure of the Earth’s crust. At depths of 10-15 km beneath Simushir Island and the Bussol Strait a high-velocity (7.5-7.7 km/sec.) layer about 4 km thick was revealed. It is related to sheet intrusion of basaltoids or a cover of andesite-basalt composition which outflew at an earlier stage of the Earth’s crust formation. In the northern part of Simushir Island beneath the Prevo and Uratman Volcanoes, at depths of 12-15 km and elsewhere were established low-velocity areas. They are linked to magmatic chambers of volcanoes defined in the area by the method of the converted waves. The thickness of the Earth’s crust was estimated at 30-32 km; in this connection the Kuril island arc is referred to mature-type ensialic arcs.

V.B.Kaplun
Preliminary results of deep magnetotelluric soundings carried out along the
Obluchie - Lake Gassi profile (Khabarovsk Territory).
The results of deep magnetotelluric soundings are considered which were carried out along the near-latitudinal profile, starting within the Bureyan Massif and crossing its eastern boundary, the Middle Amur Depression and terminating in the western area of the Sikhote-Alin fold system. The analysis of the amplitude curve distortion is made, and the geoelectrical section and one-dimensional model in a first approximation are constructed. The geoelectrical inhomogeneities within the upper mantle are revealed, and their connection with major tectonic faulting and tectonic structure of the area under study is marked.

L.I.Morozova
Meteorological satellite images as the bearers of information on seismicity
Linear Cloudy Anomalies (LCA) are a long-known natural phenomenon. Above the faults of the Earth’s crust, LCA are due to the crust increase and to the tectonic movements in the region. LCA dynamics was shown on meteorological satellite images before seismic developments and after them, as exemplified by the earthquakes in the Middle East, Middle Asia, India, China, Sakhalin Island (Neftegorsk), and Honshu (Kobe).

All catastrophic earthquakes follow an anomalously great quantity of LCA (in comparison with the background values in the region) several hours or a day prior to the first tremor. Regular meteorological satellite images have also recorded radio interference as image distortion stripes caused by seismic sources of electromagnetic anomalies. LCA and radio interference may be considered as indicators of a seismotectonic process. They may be used as a short-term precursor of the place and time of an earthquake. Meteorological satellite images are useful means for space geodynamic monitoring.

V.G.Bykov
Mechanism of soliton formation due to stick-slip in the crustal fault
The possibility of formation of the rupture soliton due to stick-slip in the crust is studied on the basis of the model of intergranular sliding which is analogous to the model by Frenkel-Kontorova elaborated for movement of dislocations in the crystals. As a result of mathematical modeling two waves appear which are characterized by the soliton properties: the shear wave propagated in the direction normal to fault and the rupture wave moving along the fault. It is shown that under certain conditions the solitary wave appears in the granular geomaterials which is described by the sin-Gordon equation. The expressions are obtained for the transverse displacement and particle velocity of the ground near the stick-slip area and also for the shear and rupture wave velocities. The results of the calculations made are consistent with the real parameters of waves from the earthquakes.

V.A.Akhmadulin
Electromagnetic forerunners of the earthquakes
Electromagnetic forerunners of the earthquakes are considered which were recorded under different conditions prior to the appreciable tremors, but irregularity and diversity of their manifestation do not permit looking forward to reliable forecast. It is presumed that they are of endogenic character, and are linked to the processes of preparation of earthquakes; the emergence of electromagnetic radiation on the day surface is largely determined by the geoelectrical section, in which the presence of waveguides can explain a transition of such kind of radiation from the source zone to the atmosphere and ionosphere.