Seismotectonic Deformations Related to the 2011 Tohoku Earthquake at Different Stages of the Seismic Cycle,Based on Satellite Geodetic Observations

Doklady Earth Sciences - The data of multiannual satellite geodetic observations before, during, and after the 2011 Tohoku earthquake are interpreted on the basis of the keyboard model of the...     

Ore potential of the Marcus-Wake rise (Central Pacific)

The data on the geological structure of different guyots on the Marcus-Wake rise with cobalt-bearing Fe–Mn crusts are discussed. Crusts are represented by three-layer aggregates composed of one lower phosphatized (I-1) and two upper non-phosphatized (II and III) layers. Fe-vernadite and Mn-feroxygite are the major ore minerals in all studied crusts and their layers. Small contents of vernadite, asbolane–buserite, and goethite are registered. Crusts of guyots on the rise are characterized by a stable concentration of heavy and rare metals (Co_tot, Ni, Cu, Zn, Pb, Mo, and Cd) independently of their latitudinal location.     

Regularities of ore formation in mid-ocean ridges

The regularities of the concentration of ore matter in the mid-ocean ridges are considered, and the mechanisms of hydrothermal and cumulative treatment of the crust by ore elements are substantiated.     

The Komandor seismic gap: Earthquake prediction and tsunami computation

The “seismic silence” period in the seismic gap in the region of the Komandor Islands (hereinafter, the Komandor seismic gap) is close to the duration of the maximal recurrence interval for the strongest earthquakes of the Aleutian Islands. This indicates the possibility of a strong earthquake occurring here in the nearest time. In the present work, the results of simulation for a tsunami from such an earthquake are presented. The scheme successfully used by the authors for the nearest analog—the 2004 Sumatra-Andaman earthquake—is applied. The magnitude of the supposed earthquake is assumed to be 9.0; the tsunamigenic source is about 650 km long and consists of 9 blocks. The parameters of the tsunami propagation in the Pacific Ocean and the characteristics of the waves on the coasts are computed for several possible scenarios of blocks’ motion. The spectral analysis of the obtained wave characteristics is made and the effects of the wave front interference are found. Simulation has shown that the wave heights at some coastal sites can reach 9 m and, thus, may cause considerable destruction and deaths.     

Numerical Modeling of Sediment Mass Sliding and Tsunami Generation: The Case of February 7, 1963, in Corinth Gulf, Greece

Numerical modeling of a landslide process at the continental slope by taking into account slope parameters is performed for the tsunami event of February 7, 1963, reported in the Corinth Gulf, central Greece. A layered sediment structure was considered, and an initial external dynamic action at the landslide process was introduced. The results obtained were quite consistent with the observational runup data as well as with the results arrived at by conventional rigid-body and viscous-fluid models. However, this approach permits to describe in detail the formation of several wave groups and particular tsunami characteristics that are strongly dependent on the landslide model.     

A mathematical model of gas outflow from gas-saturated ice and gas hydrates

This paper considers gas outflow from the agglomerate composed of gas-saturated ice, free gas, and gas hydrates. The agglomerate is considered to be a multicomponent continuous medium.     

New data on seismicity of the middle Caspian Basin and their possible tectonic interpretation

Short-term (three months) bottom seismic observations in the area of the Yalam-Samur structure in the Middle Caspian Basin revealed a deep-seated compact zone of mantle-earthquake sources that dips beneath the southeastern Caucasus. To a first approximation, this zone may be interpreted as a seismofocal layer that characterizes thrusting of the Turan Plate under the southeastern Caucasus. However, the obtained spatial distribution of sources of microearthquakes and weak earthquakes is insufficiently reliable owing to the low aperture of the observation network of bottom seismographs. More reliable data on the position and parameters of the seismofocal layer could be obtained by the observation network with a wider spread of bottom seismographs (up to 50–100 km). If this result is confirmed, the current concept of interaction between the Alpine structures of the southeastern Caucasus, Turan, and South Caspian plates should probably be revised. The geotectonics of the Caucasus is preliminarily analyzed in the light of the newly revealed relationships.     

Submarine landside in the Bussol Graben: Structural and formation features

Analysis of geophysical data obtained during a study of the insular slope in the central Kuril?Kamchatka Trench during projects Kuriles-2005 and Kuriles-2006 promoted by the Presidium of the Russian Academy of Sciences revealed a large submarine landslide in this area. The landslide, located at the bottom of the transverse valley confined to the Bussol l Graben, resulted from the failure of the northeastern wall of a graben composed of sedimentary material. It exceeds 35 km³ in size, representing one of the large submarine landslides discovered to date on the slope of the Kuril?Kamchatka Trench in submarine canyonfan environments.     

On the seismic hazard of the Bolshoi Sochi region

In connection with the intensive development of the northeastern part of the Black Sea, at present a number of serious technical, scientific, and ecological problems have arisen. As the constructions being raised are of large sizes and they are designed for a long period of use, the probability of their damage by natural phenomena significantly increases. First of all, these are phenomena connected with seismotectonic activity. In the present paper, the current concepts about the regional tectonic structure are considered. Moreover, a detailed analysis of the seismic activity in the Bolshoi Sochi region and the adjacent regions is conducted in the historical perspective. The basic results of the marine seismic research carried out by the Institute of Oceanology of the Russian Academy of Sciences on the shelf and the continental slope of the northeastern part of the Black Sea during the period of 1998–2001 are presented. On the basis of the scheme of the general seismic zoning developed by the International Expert Group for the Caucasian Region, a scheme of the seismic hazard in the Bolshoi Sochi region has been constructed. For the specific zones of the region, the values of the seismic hazard characteristics—the maximum shocks and accelerations and the periods of oscillations under maximum seismic effect—have been calculated. Some ideas concerning the integrated modernization of the system for seismological observations in this region, including the deployment of autonomous bottom seismographs and automatic seismographs in almost inaccessible places, are proposed.