Electromechanical phenomena associated with earthquakes   总被引：2，自引：0，他引：2  

Renata Dmowska 《Surveys in Geophysics》1977,3(2):157-174

This article reviews the field, laboratory, and theoretical investigations made concerning different electromechanical phenomena associated with earthquakes. It discusses laboratory measurements of electrical resistivity of rocks stressed up to fracture, particular attention being paid to the interpretation of results according to the diffusion-dilatancy theory. This is followed by the discussion of field measurements of electrical characteristics of rocks in seismic areas in connections with seismic activity in these regions. Piezoelectric and electrostrictive phenomena are briefly discussed, and also a theoretical model of electro-elastic effects associated with an earthquake source. The last part concerns electrokinetic phenomena in porous rocks, caused by the diffusion of fluids into the dilatant focal region. The divergence of opinion about the physical models of the earthquake process is emphasized.  相似文献   

Electromechanical effects associated with earthquakes     

Renata Dmowska  Andrzej Hanyga  Roman Teisseyre 《Pure and Applied Geophysics》1977,115(4):1033-1046

Summary A theoretical model of an electroelastic continuum has been applied in this paper to the problem of electrodynamic phenomena (piezoelectricity, electrostriction, etc.) associated with earthquakes. In such a model the coupling between electric and mechanical fields expresses itself by a change of scale of mechanical effects along the electric field, as well as by the additional electric charge created by the earthquake source.The electrokinetic phenomena associated with earthquakes and caused by the diffusion of fluids into the dilatant region have been considered using the theory of porous media with interstitial fluid flow. General relations describing electrokinetic effects caused by the deformation processes in an earthquake source have been obtained.  相似文献   

Miocene to Quaternary deformation in NE Slovenia: complex paleomagnetic and structural study     

Em Mrton  Lszl Fodor  Bogomir Jelen  Pter Mrton  Helena Rifelj  Renata Kevri 《Journal of Geodynamics》2002,34(5)

Combined paleomagnetic and structural research was carried out in the Mura-Zala Basin including the western and southern surrounding hills in northeastern Slovenia. The Mura-Zala Basin was formed due to ENE–WSW trending crustal extension in the late Early Miocene (18.3–16.5 Ma). First, marine sedimentation took place in several more or less confined depressions, then in a unified basin. During thermal subsidence in the late Miocene deltaic to fluvial sediments were deposited. After sedimentation, the southernmost, deepest depression was inverted. Map-scale folds, reverse and strike-slip faults were originated by NNW–SSE compression. This deformation occurred in the latest Miocene–Pliocene and is reflected also in the magnetic fabric (low field susceptibility anisotropy). After this folding, the Karpatian sediments of the Haloze acquired magnetization, then suffered 30° counterclockwise rotation relative to the present north (40° counterclockwise with respect to stable Europe). This Pliocene (Quaternary?) rotation affected a wide area around the Mura-Zala Basin. The latest Miocene to Quaternary folding and subsequent rotation may be connected to the counterclockwise rotation of the Adriatic microplate.  相似文献   

Relationship between the ionospheric potential and the ground-level electric field in the southern polar cap     

R. Yu. Lukianova  A. A. Kruglov  A. V. Frank-Kamenetskii  A. L. Kotikov  G. B. Berns  V. D. R. French 《Geomagnetism and Aeronomy》2011,51(3):383-393

The relationships between the average hourly values of the vertical ground-level electric field measured at the Vostok Antarctic station and the ionospheric potential above the station have been obtained. The ΔEz and Uext parts of both parameters controlled by the solar wind were considered. Convection models (Weimer, 1995; Lukianova and Christiansen, 2006) and a model based on the SuperDARN radar system were used to determine the ionospheric potential. An analysis has been performed for isolated days and the entire sample in 1998–2000 (including 170 days of “fine weather”). For an isolated day, the best correlation coefficients (R) between ΔEz and Uext obtained using the three models were 0.81, 0.80, and 0.88, respectively. The total correlation coefficient for the entire data set was R = 0.24−0.32. The R value was larger during daytime (R ≈ 0.4) and smaller at night (R ≈ 0.1) and slightly increased in the early morning hours. The specific features of daily variations in R apparently indicate that it is possible to adequately describe the structure of the ionospheric electric field equipotentials by using large-scale stationary convection models. The R value varies complexly, depending on the IMF orientation, but it generally tends to increase from IMF By < 0 to By > 0, which is explained by the asymmetric convection patterns for opposite By signs.  相似文献   

Effect of the <Emphasis Type="Italic">d</Emphasis> electrons on phase transitions in transition-metal sesquioxides     

Koichiro Umemoto  Renata M. Wentzcovitch 《Physics and Chemistry of Minerals》2011,38(5):387-395

We present a systematic density-functional study of phase relations in three 4d-transition-metal sesquioxides: Y₂O₃, Rh₂O₃, and In₂O₃. Y₂O₃ and In₂O₃ undergo pressure-induced transitions to phases with larger cation coordination number (from 6 to 7) at low pressures. However, this does not occur in Rh₂O₃ at least up to ~300 GPa. This cannot be explained by usual arguments based on ionic-radii ratios often used successfully to explain phase relations in simple-metal and rare-earth sesquioxides and sesquisulfides. Inspection of their electronic structures shows that, in Rh₂O₃, the electronic occupancy of 4d orbitals, 4d ⁶, plays a fundamental role in the extraordinary stability of the Rh₂O₃(II)-type phase with respect to coordination increase. We point out that d-orbital occupancy is a fundamental factor in explaining phase relations in transition-metal sesquioxides and sesquisulfides.  相似文献   

Acknowledgement     

Keiiti Aki  Renata Dmowska 《Pure and Applied Geophysics》1987,125(6):1119-1120

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Gully erosion as a natural hazard: the educational role of geotourism     

Zg&#;obicki  Wojciech  Ko&#;ody&#;ska-Gawrysiak  Renata  Gawrysiak  Leszek 《Natural Hazards》2014,70(1):159-172

Gully erosion is one of the greatest natural hazards in the loess areas of E. (Eastern) Poland. At the same time, permanent gullies are a major tourist attraction and can provide a basis for the development of geotourism. The study objective was to assess the possibilities of using the loess gullies for educational purposes. Detailed studies were conducted within the municipality of Kazimierz Dolny, an area with an extremely high concentration of permanent gullies. The questionnaire survey of students and tourists (nearly 300 surveys were completed) showed that the respondents’ knowledge of geomorphology was limited, despite their familiarity with gullies. In most cases, they were unable to accurately identify the determinants of gully erosion, its negative effects and methods for preventing it. An assessment of the tourism and geotourism potential of the municipality made it possible to identify the sites (gullies) that can perform an educational function, with regard to gully erosion. The establishment of the Małopolska Vistula Gap Geopark, whose highlights will include numerous loess gullies, can pave the way for the development of geotourism.

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Pattern and timing of the northwestern Barents Sea Ice Sheet deglaciation and indications of episodic Holocene deposition   总被引：1，自引：0，他引：1  

Denise Christina Rüther  Lilja Rún Bjarnadóttir  Juho Junttila  Katrine Husum  Tine Lander Rasmussen  Renata Giulia Lucchi  Karin Andreassen 《Boreas: An International Journal of Quaternary Research》2012,41(3):494-512

The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice‐rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner‐fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.  相似文献   

Climate Change Impact on Hydrological Extremes: Preliminary Results from the Polish-Norwegian Project   总被引：2，自引：1，他引：1  

Renata J. Romanowicz  Ewa Bogdanowicz  Sisay E. Debele  Joanna Doroszkiewicz  Hege Hisdal  Deborah Lawrence  Hadush K. Meresa  Jaroslaw J. Napiórkowski  Marzena Osuch  Witold G. Strupczewski  Donna Wilson  Wai Kwok Wong 《Acta Geophysica》2016,64(2):477-509

This paper presents the background, objectives, and preliminary outcomes from the first year of activities of the Polish–Norwegian project CHIHE (Climate Change Impact on Hydrological Extremes). The project aims to estimate the influence of climate changes on extreme river flows (low and high) and to evaluate the impact on the frequency of occurrence of hydrological extremes. Eight “twinned” catchments in Poland and Norway serve as case studies. We present the procedures of the catchment selection applied in Norway and Poland and a database consisting of near-natural ten Polish and eight Norwegian catchments constructed for the purpose of climate impact assessment. Climate projections for selected catchments are described and compared with observations of temperature and precipitation available for the reference period. Future changes based on those projections are analysed and assessed for two periods, the near future (2021–2050) and the far-future (2071–2100). The results indicate increases in precipitation and temperature in the periods and regions studied both in Poland and Norway.  相似文献   

Evaluation of community leaders’ perception regarding Alerta Rio,the warning system for landslides caused by heavy rains in Rio de Janeiro     

Patricia de Oliveira Melo  Renata Marques de Britto  Tharcisio Cotta Fontainha  Adriana Leiras  Renata Albergaria de Mello Bandeira 《Natural Hazards》2017,89(3):1343-1368

Warning systems help reduce damage and save lives in disasters; however, there is a lack of research analyzing the population perception of these systems. In Rio de Janeiro (Brazil), because the city slums face the risk of landslides caused by heavy rains, a siren early warning system named “Alerta Rio” was installed in 102 areas. The purpose of this paper was to understand the perception of community leaders regarding this alert system. To this end, a survey was conducted with community leaders to collect data on whether and why the public do or do not attend to the alert. Results indicated that (1) public adherence to Alerta Rio is low despite the generally positive view of the system, (2) local violence was reported as the reason for staying at home to protect one’s property, and (3) problems with temporary shelters and the routes to them result in lack of people’s involvement in the system. Whereas these factors are similar to population perception regarding other warning systems, the community leaders also raised the public’s lack of trust in the city hall’s adopted concept of risk and in the politicians as a relevant factor in the population perception of Alerta Rio. These factors, together with the lack of prevention policies complementary with the alert system, led to perception of reduced importance of the system. For potential solutions to enhance alarm compliance, this study recommends improvement in communication, educational programs, and public engagement strategies tailored for each target group.  相似文献