Using numerical modelling to evaluate tsunami hazard near the Kuril Island

A sequence of computer experiments is used to study questions concerning the tsunami problem as a quantitative estimate of tsunami danger, detailed geographical tsunami classification, determination of the parameters of critical tsunami waves, and the conditions of their development. We call a wave critical, if its impact on the coast is most hazardous.Using the Middle Kuril Island as an example, we present the results of a computer experiment which includes determining the wavefields on the shelf and estimating the effects connected with the deep-water Bussol and Diana Straits.Numerical simulation of tsunami waves of different sources permits the assessment of the extent of tsunami danger in different areas of the coastal zone of Simushir Island, depending on the location of the focus zone and their geometry.The major singularities of the wavefield arise in the zones of the deep-water straits. The distribution of the amplification factors is determined by both the global parameters of the wavefields and the local properties of individual harbours. The results obtained for a particular harbour in the northern part of Simushir Island, formed the basis for the quantitative estimate of tsunami danger for this area.     

Seismic hazard monitoring in Kamchatka and its applications to the M = 6.6 earthquake of 6 October 1987

The earthquake of 6 October 1987 (M = 6.6), which occurred near the Shipunsky Cape, Kamchatka, was the largest crustal event in the vicinity of the main city of Kamchatka — Petropavlovsk-Kamchatsky — during the last three decades. It was followed by numerous aftershocks. This earthquake allowed us to test the effectiveness of the seismic hazard monitoring in Kamchatka, including the seismological, geodetic and hydrogeochemical surveys. The seismic survey provided the location and source nature of the main shock and aftershocks and the seismic environment of the main shock. The geodetic and hydrogeochemical surveys have yielded data on the response to earthquakes of the Earth's surface deformations, water level, and chemical elements concentration in the underground water. As a result, the following data were obtained:

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The earthquake of 6 October had a seismic moment 4–10 E18 Nm, thrust type of faulting and the source volume of 20 × 20 × 10 km³. The maximum intensity was VI–VII (MSK-64 scale) and maximum acceleration 88 cm/s².

Before this event, a relative increase in the number of the upper mantle (depth more than 100 km) moderate magnitude earthquakes during 5 years and a one-year period of seismic quiescence for small shallow earthquakes, were recognized. Significant anomalies in HCO₃ and H₃BO₃ concentrations in the underground waters were observed in the wells a week before the main shock.

     

TREK: A cosmic-ray experiment on the Russian space station MIR

The goals of the TREK experiment, now in place on the MIR Space Station, are to resolve and measure the composition of both odd-Z and even-Z cosmic-ray nuclei up to uranium, to measure the isotopic composition of Fe-group nuclei, and to search for transuranic nucleic and exotic particles such as strangelets. To collect tracks of ultraheavy cosmic rays, exterior panels holding an array of BP-1 phosphate glass 1.2m² in area and 16 plates thick are now mounted outside the Kvant-2 module on MIR. Heaters and relays regulate the temperature of the glass at 25°±5°C. The detectors will record 10³ cosmic-ray tracks withZ50 during 2.5 years. An interior panel consisting of an array 0.09 m² in area and 32 plates thick and mounted on the inside wall of the Soyuz spacecraft (attached to the Space Station) will collect tracks of about 13000 Fe and 500 Ni nuclei.     

Geographical and economic determinants of interregional migration in the USSR, 1968-1985

"Interregional migration results in a regional redistribution of labor, essential under the current mismatch between the locations of labor and of natural resources and industrial capacity in the USSR. This study focuses on economic and geographical determinants of destination choice of migrants from 1968 through 1985. Particular emphasis is placed upon the relative effects of economic variables and quality of life factors and on the effect of gravity variables (i.e., distance and population size). The statistically significant results for the economic and gravity variables indicate the appropriateness of using Western theories to analyze migration in the Soviet context."     

Magnetoacoustic surface waves at a single interface

The occurrence of magnetoacoustic surface waves at a single magnetic interface one side of which is field-free is explored for the case of non-parallel propagation. Phase-speeds and penetration depths of the waves are investigated for various Alfvén speeds, sound speeds and angles of propagation to the applied field. Both slow and fast magnetoacoustic surface waves can exist depending on the values of sound speeds and propagation angle. The fast waves penetrate more than the slow waves.The parallel propagation of fast and slow magnetoacoustic surface waves on a magnetic-magnetic interface is investigated. The slow surface wave is unable to propagate below a critical sound speed. In a low -plasma, only the fast mode exists (0 0).     

Geology and tectonics of the Themis Regio-Lavinia Planitia-Alpha Regio-Lada Terra area,Venus: Results from Arecibo image data

New radar images obtained from the Arecibo Observatory (resolution 1.5–4.0 km) for portions of the southern hemisphere of Venus show that: the upland of Phoebe Regio contains the southern extension of Devana Chasma, a rift zone extending 4200 km south from Theia Mons and interpreted as a zone of extension; Alpha Regio, the only large region of tessera within the imaged area, is similar to tessera mapped elsewhere on the planet and covers a smaller percentage of the surface than that observed in the northern high latitudes; the upland made of Ushas, Innini and Hathor Montes consists of three distinct volcanic constructs; Themis Regio is mapped as an ovoid chain of radar-bright arcuate single and double ring structures, edifices and bright lineaments. This area is interpreted as a region of mantle upwelling and on the basis of apparent split and separated features, a zone of localized faulting and extension. Linear zones of deformation in Lavinia Planitia are characterized by lineament belts that are often locally elevated, are similar to ridge belts mapped in the northern high latitudes and are interpreted to be characterized mainly by compression; radar-bright lava complexes within Lavinia Planitia are unique to this part of the planet and are interpreted to represent areas of eruption of high volumes of extremely fluid lava; the upland of Lada Terra is bound to the north by a linear deformation zone interpreted as extensional, is characterized by large ovoids and coronae, is interpreted to be associated with an area of mantle upwelling, and is in contrast to the northern high latitude highland of Ishtar Terra. Regions of plains in the southern hemisphere cover about 78%; of the mapped area and are interpreted to be volcanic in origin. Located within the area imaged (10–78 S) are 52 craters interpreted to be of impact origin ranging from 8 to 157 km in diameter. On the basis of an overall crater density of 0.94 craters/10⁶ km², it is determined that the age of this part of the Venus surface is similar to the 0.3 to 1.0 billion year age calculated for the equatorial region and northern high latitudes. The geologic characteristics of the portion of the Venus southern hemisphere imaged by Arecibo are generally similar to those mapped elsewhere on the planet. This part of the planet is characterized by widespread volcanic plains, large volcanic edifices, and zones of linear belt deformation. The southern hemisphere of Venus differs from northern high latitudes in that tessera makes up only a small percentage of the surface area and the ovoid chain in Themis Regio is unique to this part of the planet. On the basis of the analysis presented here, the southern hemisphere of Venus is interpreted to be characterized by regions of mantle upwelling on a variety of scales (ovoids, region made up of Ushas, Innini and Hathor Montes), upwelling and extension (Themis Regio) and localized compression (lineament belts in Lavinia Planitia).     

Results of TV imaging of Phobos (Experiment VSK-Fregat)

From February to March 1989 the Phobos 2 spacecraft took 37 TV images of Phobos at a distance of 190-1100 km. These images complement Mariner-9 and Viking data by providing higher-resolution coverage of a large region West of the crater Stickney (40-160 degrees W) and by providing disk-resolved measurements of surface brightness at a greater range of wavelengths and additional phase angles. These images have supported updated mapping and characterization of large craters and grooves, and have provided additional observations of craters' and grooves' bright rims. Variations in surface visible/near-infrared color ratio of almost a factor of 2 have been recognized; these variations appear to be associated with the ejecta of specific large impact craters. Updated determinations of satellite mass and volume allow calculation of a more accurate value of bulk density, 1.90 +/- 0.1 g cm-3. This is significantly lower than the density of meteoritic analogs to Phobos' surface, suggesting a porous interior perhaps containing interstitial ice.     

Earthquake hazard of the northern parts of the Bohemian Massif and Western Carpathians

The new procedure of earthquake hazard evaluation developed by Kijko and Sellevoll is tested and applied for the border region of Czechoslovakia and Poland. The new method differs from the conventional approach. It incorporates the uncertainty of earthquake magnitudes, and accepts mixed data containing only large historical events and recent, complete catalogues. Seismic hazard has been calculated for nine regions determined in the border area. In the investigated area, data of historical catalogues are uncertain or, in many cases, the epicentral intensities are unknown. Thus, a number of assumptions have to be adopted in data preparation of catalogues since the year 1200. The calculated values of parameters b in the Gutenberg-Richter frequency-intensity relation as well as the return periods, seem to be reasonable and are generally confirmed by the results obtained from catalogues for the last 80–130 years.     

Catastrophic landslip activity in two hard rock terrains of peninsular India

This paper presents the case histories of two catastrophic landslips in hard rock terrains with varied climatic and geological environments. The first slip is associated with a power project in very close proximity (200 m) of the Porthimund Dam (11°22N, 76°3430E), in a charnockitic terrain in the Nilgiri hills (Tamil Nadu), and the second is associated with a railroad structure (19°525N, 78°1720E), in Adilabad district (Andhra Pradesh), in a basaltic terrain.The landslip in the charnockites is attributable to: (1) a high degree of saprolitization in the charnockites, with maximum intensity in the crest portion; (2) the coincidence of a major joint pattern in a NE-SW direction, with the strike of the foliation; and (3) the poor-to-fair physical rock quality in the crest and scarp portions.The slips in the basaltic terrain are due to: (1) the partially altered, highly jointed nature of the regional trap rocks with boulder sizes varying from 20 cm to 250 cm in diameter and the debris accumulating in a precarious condition on the northeast side of the rail track, with unfavorable alignment direction; and (2) the instability created in the weak rock mass by the vibrational forces of heavily loaded running trains.The weathered state of the rock masses in both the cases, showing good agreement with their physical state, accounts for the landslips. The remedial measures suggested are also discussed.     

Re-analysis of close binary systems

Line-forming regions around close binaries with strong winds ( /4r _* v 10^–4 g cm^–2) are large in extent compared with the stars, large enough to screen them. Their orbitally-modulated Doppler shifts can overestimate the mass function, because of a larger rotational lever arm. In particular, most of the black-hole candidates need not involve companions more massive than a neutron star.The solar-wind problem is reconsidered. An extrapolation to Wolf-Rayet stars suggests that their winds are centrifugally driven. Their mass-loss rates tend to have been overestimated.Seemingly single (massive) stars can hide a (compact) companion.