Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission     

David E. Dunn  Lawrence A. Molnar  Imke de Pater 《Icarus》2004,171(1):183-198

We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of λ3.6 cm. The moderate ring opening angle (B≈15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae.  相似文献   

Gravitational (Rayleigh-Taylor) instability of a layer with non-linear viscosity and convective thinning of continental lithosphere   总被引：8，自引：0，他引：8  

Gregory A. Houseman  Peter Molnar 《Geophysical Journal International》1997,128(1):125-150

  相似文献   

Rupture zones of great earthquakes in the Himalayan region   总被引：1，自引：0，他引：1  

Peter Molnar  M R Pandey 《Journal of Earth System Science》1989,98(1):61-70

  相似文献   

Microearthquake seismicity and active tectonics of northwestern Greece     

G.C.P. King  A. Tselentis  J. Gomberg  P. Molnar  S.W. Roecker  H. Sinvhal  C. Soufleris  J.M. Stock 《Earth and Planetary Science Letters》1983

We carried out a microearthquake survey lasting for six weeks in northwest Greece using 18 portable seismograph stations to examine a region in which normal and thrust faulting have been reported in close proximity to one another. With this array we located 148 events and determined fault plane solutions for eight events using only rays radiated upwards. The seismicity of the region is diffuse with events extending to depths of nearly 30 km, and there is a minimum in activity near a depth of 15 km. The fault plane solutions exhibit a wide spectrum of fault types and orientations and are not consistent with simple zones of shortening or extension. Neither tractions applied to the edges or bottom of the region nor deviatoric stresses that compensate for lateral variations in crustal thickness can account for the variety of fault plane solutions. We think that the complicated behavior is a manifestation of inhomogeneous deformation due, at least in part, to a pre-existing complicated juxtaposition of structures and formations.  相似文献   

A possible dependence of tectonic strength on the age of the crust in Asia   总被引：2，自引：0，他引：2  

Peter Molnar  Paul Tapponnier 《Earth and Planetary Science Letters》1981,52(1):107-114

In Asia, the intensity and style of active tectonics appears to depend on the age of the last orogenic activity. The shields have remained essentially undeformed during the India-Eurasian collision, but Paleozoic and Mesozoic orogenic belts apparently have been reactivated by this collision, with a suggestion of greater reactivation and more diffuse deformation of the younger belts. If the greater observed heat flow in regions of more recent orogenic activity reflects, at least in part, a greater heat flow from the mantle beneath the younger belts, then the temperatures in the mantle beneath the younger belts should be higher than beneath older belts and shields. Because of the strong dependence on temperature of the creep strength of minerals, particularly of olivine, the crust and mantle beneath the hotter, younger belts should be much weaker than those beneath older belts. This difference in temperature, and consequent difference in strength, may be the cause of the greater reactivation of younger belts.  相似文献   

The rotation group in plate tectonics and the representation of uncertainties of plate reconstructions     

J. Stock  P. Molnar  T. Chang 《Geophysical Journal International》1990,101(3):649-661

  相似文献   

Groundwater quality on the territory of Kikinda municipality (Vojvodina,Serbia)     

Nenad Marić  Sanja Mrazovac Kurilić  Ivan Matić  Stanko Sorajić  Jelena Zarić 《Environmental Earth Sciences》2014,72(2):525-534

This paper provides insight into the quality of groundwater used for public water supply on the territory of Kikinda municipality (Vojvodina, Serbia) and main processes which control it. The following parameters were measured: color, turbidity, pH, KMnO₄ consumption, TDS, EC, NH₄ ⁺, Cl^?, NO₂ ^?, NO₃ ^?, Fe, Mn, total hardness, Ca²⁺, Mg²⁺, SO₄ ²⁺, HCO₃ ^?, K⁺, Na⁺, As. The correlations and ratios among parameters that define the chemical composition were determined aiming to identify main processes that control the formation of the chemical composition of the analyzed waters. Groundwater from 11 analyzed sources is Na–HCO₃ type. Intense color and elevated organic matter content of these waters originate from humic substances. The importance of organic matter decay is assumed by positive correlation between organic matter content and TDS, HCO₃ content. There is no evidence that groundwater chemistry is determined by the depth of captured aquifer interval. The main processes that control the chemistry of all analyzed water are cation exchange and feldspar weathering.  相似文献   

Vulnerability to natural disasters in Serbia: spatial and temporal comparison     

Jelena Kovačević-Majkić  Milena Panić  Dragana Miljanović  Radmila Miletić 《Natural Hazards》2014,72(2):945-968

The frequency of natural disasters and the extent of their consequences at a global level are constantly increasing. This trend is partially caused by increased population vulnerability, which implies the degree of population vulnerability due to high-magnitude natural processes. This paper presents an analysis of vulnerability to natural disaster in Serbia in the second half of the twentieth and the early twenty-first century. Vulnerability changes were traced on the basis of demographic–economic indicators derived from statistical data for local government units (municipalities) provided by the Statistical Office of the Republic of Serbia. Calculations were performed in the geographical information system environment. The results of the study show that spatial and temporal vulnerability variations are causally correlated with changes in the selected components. Significant rise of vulnerability is related to urban areas, while lower values are characteristic for other areas of Serbia; this is primarily a consequence of different population density.  相似文献   

The Origin of Outer Topographic Rises Associated with Trenches     

Barry Parsons  Peter Molnar 《Geophysical Journal International》1958,1(4):707-712

  相似文献   

Magnetic Anomalies, Bathymetry and the Tectonic Evolution of the South Pacific since the Late Cretaceous   总被引：3，自引：0，他引：3  

Peter Molnar  Tanya Atwater  Jacqueline Mammerickx  Stuart M. Smith 《Geophysical Journal International》1975,40(3):383-420

  相似文献