Magnetic field structure inside the magnetosphere in the recovery phase of a magnetic storm

Mathematical model for computing magnetic field structure in magnetosphere after magnetic stor

Underlying mechanism of precursory activity from analysis of upward earthquake migration

In this paper we analyse the upward earthquake hypocentral migration in the ten known subduction zones and discuss a possible mechanism of such migration. The total time of the migration appears to range from 2.5 to 10 years. It leads to the estimation of the average velocity <i><b>V</b></i><sub>z</sub>~ 60−300 km yr<sup>−1</sup>. It probably corresponds to the movement of the forcing agent like stress or deformation wave from depths of the upper mantle (600–700 km) to the level of the lithosphere with subsequent initiation of fluid migration inside the crust to trigger shallow earthquakes. Averaged over all zones upward migration travel time is about 5 years (< <i><b>V</b></i><sub>z</sub> > ≈120 km yr<sup>−1</sup>) that coincides approximately with the period of characteristic temperature variation (El Nino) and crustal seismic periodicity in the Pacific region. These findings are helpful for the study of the seismic precursors and analysis of earthquake triggering

Non double couple seismic sources, faults interaction and hypothesis of self-organized criticality

Non double couple (NDC) sources are considered in framework of the hypothesis that the process of seismic rupture can be viewed as a result of complicated fault geometry and its segmentation. Analytical approach is found to reveal reliability of NDC measure taking into consideration the values of seismic moment tensor errors. The study focuses on the comparison of the deformation modes of the NDC sources with the stress states in its vicinity. The deformation modes of faulting and fracturing at a small scale in NDC earthquake focus and at regional scale in geological unit were investigated using at the last case summation of seismic moment tensors. These local and regional deformation modes in some of geodynamic regimes confirm the self-similarity assumption. For the whole data set scaling relations seem to be more complicated. This feature implies that besides stresses second order factors, as the hydrothermal or magmatic pore fluids in rock, influence source characteristics and bring new complications in scaling relations

Inductive seismo-electromagnetic effect in relation to seismogenic ULF emission

International audienceDuring the seismic wave propagation through the crust, the electromagnetic pulse can originate due to MHD conversion in this conductive medium. On the assumption of simple models of seismic wave excitation and attenuation, the problem is reduced to the analysis of a diffusion-like equation for a vector potential function. In this way, we need to change the classical gauge condition. A semi-analytical form of the solution is obtained in a case with constant ground conductivity. Dependencies of the electric and magnetic field components and the pulse duration on distance and crust conductivity have been computed in detail. The results could be useful for the explanation of electromagnetic signals related to coseismic, foreshock and aftershock activity

Social tension as precursor of large damaging earthquake: legend or reality?

"La administración crónica de BSS-4 y cafeína mejora la recuperación de la memoria espacial de largo plazo y aumenta la actividad de enzimas antioxidantes en el hipocampo de rata.

VLF/LF sounding of the lower ionosphere to study the role of atmospheric oscillations in the lithosphere-ionosphere coupling

It is shown that sounding of the lower ionosphere boundary by subionospheric signals from powerful VLF/LF transmitters can be a useful tool for the investigation of Planetary Waves (PW) with periods in a range of 2-30 days. A specific spring-time transition in the PW dynamic periodograms is revealed from our analysis of several years data using Tsushima, Japan VLF transmitter (10.2kHz) along the path with length of about 1000km. Earthquake influence m the periodograms could be sometime recognized as an appearance of specific wavelets. We discuss a possibility of PW transportation from the bottom to the upper atmosphere as modulation of shorter-scale gravity waves (GW) inside the troposphere and subsequent demodulation of the GW at the atmosphere-ionosphere boundary for the explanation of observational results. The existence of modulation due to gravity waves in LF signal amplitude is presented to support the above hypothesis

A direction finding technique for the ULF electromagnetic source

International audienceA technique of direction finding is proposed, which can be applied to the magnetic-dipole type source located in the conductive ground. To distinguish a weak ULF source signal from the natural noise a network of multicomponent magnetometers is supposed to be used. The data obtained by the ground-based stations is processed in such a way that a set of partial derivatives of the magnetic perturbations due to the source are found. Comparing these derivatives with theoretical formulae makes it possible, in principle, to find the ULF source parameters such as the distance and amplitude. Averaging the data and a special procedure are proposed in order to exclude random fluctuations in the magnetic moment orientation and to avoid hydrogeological and other local factors

Tree structure data change detection method

The new method, increasing efficiency and reliability of change detection in three structures in the Internet data under indetermination of data structure (DTD, XML-Schema) is proposed in this paper. The Boolean linear programming problem was solved in two exact methods – modified Balazs with filter and modified DP method and A modified method for selecting a neural network architecture was proposed. There is also considered publish/subscribe system description enhanced with core module, which provides notifications of changes to subscribers only in case they occurred

Steady states of lattice population models with immigration

In a lattice population model where individuals evolve as subcritical branching random walks subject to external immigration, the cumulants are estimated and the existence of the steady state is proved. The resulting dynamics are Lyapunov stable in that their qualitative behavior does not change under suitable perturbations of the main parameters of the model. An explicit formula of the limit distribution is derived in the solvable case of no birth. Monte Carlo simulation shows the limit distribution in the solvable case

Preseismic ULF electromagnetic effect from observation at Kamchatka

International audienceSome results of ULF magnetic field observation at Karimshino site (Kamchatka, Russia) since June 2000 to September 2001 are presented here. Using case study we have found an effect of suppression of ULF intensity about 2?6 days before rather strong and nearby seismic shocks (magnitude M = 4.0 ? 6.2). It is revealed for nighttime and horizontal component of ULF field (G) in the frequency range 0.01 ? 0.1 Hz. Then we prove the reliability of the effect by computed correlation between G (or 1/G) and specially calculated seismic indexes Ks for the whole period of observation. Basing on the simple criteria we conclude that reliability of seismo-associated ULF suppression effect is comparable with well-known effect of connection between ULF variation and Kp index of global magnetic activity. It seems the reason of suppression is located at the atmosphere or ionosphere but not in the ground medium