Particle acceleration by double layers during kappa distributions     

N. O. Ermakova  E. E. Antonova 《Geomagnetism and Aeronomy》2007,47(4):423-428

Results of an analysis of the double layer kinetic characteristics in the case of kappa distributions are presented. The direct and classical double layers and double layers in a trap have been considered. It has been indicated that the restrictions imposed by the Bom-Block criteria are removed if trapped particle populations between the ionosphere and the electrostatic potential jump and between conjugate potential jumps are considered. The dependence of particle fluxes through the double layer in a trap, replacing the Langmuir criterion of a classical double layer, has been obtained. The applicability of the obtained results to the solution of the problem of particle acceleration in the auroral plasma has been discussed. The dependence of the current carried by precipitating magnetospheric electrons on the field-aligned potential jump and kappa distribution characteristics has been obtained.  相似文献   

Relation of geomagnetic disturbances to the dynamics of the magnetosphere and the parameters of the interplanetary medium     

O. V. Khorosheva 《Geomagnetism and Aeronomy》2007,47(5):543-547

The results of studying the dependence of the earthward shift of the magnetospheric boundaries on the magnetic storm power are generalized. The magnetosphere saturation effect, a sharp deceleration of the boundary shift at an increase in the ring current power above a certain critical level, is discussed. The geoeffectiveness of the solar wind parameters is discussed.  相似文献   

The first data on helium isotopy in a transitional clay layer at the cretaceous-paleogene boundary (Gams,Eastern Alps)     

A. F. Grachev  I. L. Kamensky  O. A. Korchagin  H. A. Kollmann 《Izvestiya Physics of the Solid Earth》2007,43(9):766-772

The paper presents preliminary results derived from the study of He isotopy in a transitional clay bed at the critical 65-Ma boundary in the Gams area (Eastern Alps). The ratio ³He/⁴He is shown to decrease from bottom to top of the transitional layer, and the difference between its values in the lower-and uppermost sublayers of the layer exceeds by more than ten times the measurement uncertainty (5%). The ratio ³He/⁴He is smallest in the upper part of the section, where all features of an impact event (spherules of pure nickel, diamonds, and awaruite) are established. The general inference of our study is that ³He enrichment in the lower part of the Gams section is related not to cosmic matter but to a change in the conditions in the source area, most likely, to volcanic activity. The effect of the latter has been established, independent of He isotopic studies, from anomalous concentrations of As, Pb, Cu, and Zn and from the presence of particles of gold, copper, and titanomagnetite similar in composition to its basaltic varieties.  相似文献   

Studying the effect of different approaches to estimating model parameters on the accuracy of river runoff simulation by SWAP model     

E. M. Gusev  O. N. Nasonova 《Water Resources》2007,34(3):277-286

Different approaches to estimating the parameters of SWAP physically based model, which describes heat and water transfer processes in the soil-vegetaion (snow) cover-atmosphere system are examined. In particular, two methods of a priori estimation of parameter values and two variants of their calibration are discussed. The parameter sets obtained by different methods were used to simulate the runoff from 12 experimental catchments in the eastern USA. The calculations were conducted for a 39-year period (1960–1998) with a 3-hour step. The results of calculations were compared with each other and with measured river runoff values in order to identify the parameter set that is optimal for runoff evaluation. A strategy is proposed for a priori parameter estimation in the case of basins where observational data are too poor to enable parameter calibration.  相似文献   

Estimation of the correlation between magnetotelluric and geothermal data in the Bishkek geodynamic research area     

O. K. Zakharova  V. V. Spichak  A. K. Rybin  V. Yu. Batalev  A. G. Goidina 《Izvestiya Physics of the Solid Earth》2007,43(4):297-303

The paper analyzes the correlation between the electrical conductivity and temperature in the upper crust of the Bishkek geodynamic research area (the Northern Tien Shan). Electrical conductivity profiles constructed from magnetotelluric data and thermograms from the boreholes near magnetotelluric sounding (MTS) points are used for estimations. The correlation analysis of conductivity and temperature profiles to depths of 3–4 km showed that, first, the correlation coefficients do not depend on the distance between the borehole and the nearest MTS point; second, the good correlation between the conductivity and temperature observed for the majority of borehole-MTS point pairs is accounted for by the fact that the study parameters vary with depth in a manner normal for laminated sedimentary rocks; and, third, a low correlation is due to specific features of the geological structure between the borehole and MTS point under consideration.  相似文献   

Geochemical modeling of magma mixing and magma reservoir volumes during early episodes of Kīlauea Volcano’s Pu‘u ‘Ō‘ō eruption     

Patrick J. Shamberger  Michael O. Garcia 《Bulletin of Volcanology》2007,69(4):345-352

Geochemical modeling of magma mixing allows for evaluation of volumes of magma storage reservoirs and magma plumbing configurations. A new analytical expression is derived for a simple two-component box-mixing model describing the proportions of mixing components in erupted lavas as a function of time. Four versions of this model are applied to a mixing trend spanning episodes 3–31 of Kilauea Volcano’s Puu Oo eruption, each testing different constraints on magma reservoir input and output fluxes. Unknown parameters (e.g., magma reservoir influx rate, initial reservoir volume) are optimized for each model using a non-linear least squares technique to fit model trends to geochemical time-series data. The modeled mixing trend closely reproduces the observed compositional trend. The two models that match measured lava effusion rates have constant magma input and output fluxes and suggest a large pre-mixing magma reservoir (46±2 and 49±1 million m³), with little or no volume change over time. This volume is much larger than a previous estimate for the shallow, dike-shaped magma reservoir under the Puu Oo vent, which grew from ∼3 to ∼10–12 million m³. These volumetric differences are interpreted as indicating that mixing occurred first in a larger, deeper reservoir before the magma was injected into the overlying smaller reservoir. Electronic Supplementary Material Supplementary material is available at and is accessible for authorized users.  相似文献   

Direction and relative paleointensity of the geomagnetic field in the middle and later pleistocene from paleomagnetic data of the Roxolany section (Ukraine)     

O. V. Pilipenko  Z. V. Sharonova  V. M. Trubikhin 《Izvestiya Physics of the Solid Earth》2007,43(5):430-441

The lower part of the Roxolany section (Ukraine) is studied, and paleomagnetic and petromagnetic characteristics of rock samples are obtained for the time interval 300-75 ka. Detailed curves of variations in angular parameters of the geomagnetic field are constructed in the entire time interval, and curves of variations in the relative paleointensity are obtained for the interval 300-180 ka. Using the values of the angular parameters and the deviations of the virtual geomagnetic pole from the position of the stationary field, anomalous directions compatible with the Jamaica excursion are identified in the intervals 250-249 and 221-220 ka. The geomagnetic field evolution is studied by methods of wavelet analysis, and the field generation process is shown to vary in the interval 300-180 ka.  相似文献   

The geomagnetic field recorded in sediments of the Tuzla section (the Krasnodar Territory,Russia) over the time interval 120–70 ka     

O. V. Pilipenko  N. Abrahamsen  V. M. Trubikhin 《Izvestiya Physics of the Solid Earth》2007,43(8):691-701

Petro-and paleomagnetic methods are applied to the study of the lower part of the Early Pleistocene Tuzla section on the Black Sea coast of the Taman Peninsula, This part of the section is composed of marine and lagoonal sediments deposited over the time interval 120–70 ka. The measured curves of the variation in the geomagnetic field inclination reveal an anomalous direction dated at ～110 ka that coincides with a similar anomalous direction in the Eltigen section (Ukraine) correlating with the Blake paleomagnetic event. The significant correlation between the time series NRM_0.015/SIRM_0.015 (Tuzla section) and the world composite Sint-800 curve indicates that the curve NRM_0.015/SIRM_0.015 in the interval 110–70 ka actually reflects the variation in the relative paleointensity of the geomagnetic field.  相似文献   

The andesite extrusion of Mount Mishennaya, Kamchatka, and its age     

V. S. Sheimovich  D. I. Golovin  D. O. Gertsev 《Journal of Volcanology and Seismology》2007,1(4):248-253

The hornblende andesite extrusion of Mount Mishennaya belongs to the andesite subcomplex of the Avacha Neopleistocene-Holocene basalt-andesite volcanic complex. The Mishennaya dome belongs to the extrusive areal field found on the north bank of Avacha Creek. It is believed that the subcomplex took a long time to develop from the Early to Late Neopleistocene. Three K-Ar age determinations of the Mishennaya andesites have been made using a hornblende monofraction for one determination and the nonmagnetic fraction of the rocks for the other two. The resulting age values are 0.60, 0.57, and 0.59 Myr. These are consistent with previous paleomagnetic determinations and with results from fission track analysis (0.7 Myr).  相似文献   

Why the Sacramento Delta area differs from other parts of the great valley: Numerical modeling of thermal structure and thermal subsidence of forearc basins     

V. O. Mikhailov  T. Parsons  R. W. Simpson  E. P. Timoshkina  C. Williams 《Izvestiya Physics of the Solid Earth》2007,43(1):75-90

Data on present-day heat flow, subsidence history, and paleotemperature for the Sacramento Delta region, California, have been employed to constrain a numerical model of tectonic subsidence and thermal evolution of forearc basins. The model assumes an oceanic basement with an initial thermal profile dependent on its age subjected to refrigeration caused by a subducting slab. Subsidence in the Sacramento Delta region appears to be close to that expected for a forearc basin underlain by normal oceanic lithosphere of age 150 Ma, demonstrating that effects from both the initial thermal profile and the subduction process are necessary and sufficient. Subsidence at the eastern and northern borders of the Sacramento Valley is considerably less, approximating subsidence expected from the dynamics of the subduction zone alone. These results, together with other geophysical data, show that Sacramento Delta lithosphere, being thinner and having undergone deeper subsidence, must differ from lithosphere of the transitional type under other parts of the Sacramento Valley. Thermal modeling allows evaluation of the rheological properties of the lithosphere. Strength diagrams based on our thermal model show that, even under relatively slow deformation (10⁻¹⁷ s⁻¹), the upper part of the delta crystalline crust (down to 20–22 km) can fail in brittle fashion, which is in agreement with deeper earthquake occurrence. Hypocentral depths of earthquakes under the Sacramento Delta region extend to nearly 20 km, whereas, in the Coast Ranges to the west, depths are typically less than 12–15 km. The greater width of the seismogenic zone in this area raises the possibility that, for fault segments of comparable length, earthquakes of somewhat greater magnitude might occur than in the Coast Ranges to the west. The text was submitted by the authors in English.  相似文献