排序方式： 共有39条查询结果，搜索用时 609 毫秒
11.
Merzouk Ouyed Mouloud Idres Amar Bourmatte Mohamed Salah Boughacha Sadek Samai Abdelkrim Yelles Abderrahmene Haned Chafik Aidi 《Journal of Seismology》2011,15(2):173-189
In order to try to identify the seismogenic sources in the epicentral area, we interpreted data collected from gravity and
aftershocks in the eastern part of the Mitidja basin after the occurrence of the 21 May 2003 Boumerdes earthquake (Mw = 6.8).
The residual gravity anomaly and the horizontal gradient maps revealed the basement shape and density discontinuities. A seismotectonic
model obtained from the aftershocks distribution and gravity data is proposed. This model highlights three active faults:
one offshore and two onshore. The offshore reverse fault striking NE-SW, parallel to the coast, is consistent with the USGS
focal mechanism of the main event, which is assumed to have the most moment release. The two onshore dipping blind active
faults are postulated at crossing angles near the SW tip of the main fault. The interpretation is based mainly on the re-location
and distribution of aftershocks, and their focal solutions. It is also supported by the basin structures obtained from the
inversion and interpretation of residual gravity anomalies, as well as by additional compiled information such as the pattern
of coastal co-seismic uplift. This configuration puts forward the failure mode complexity during the main shock. The topography
of the basement obtained from 3D gravity inversion shows that all the onshore located aftershocks occurred in the basement,
and the area between the two onshore faults rose as a consequence of their sliding. 相似文献
12.
Weak ion-acoustic solitary waves (IASWs) in unmagnetized plasmas having two-fluid ions and kappa-distributed electrons are considered. The effects of electron suprathermality, warm ion temperature and polarity on the nonlinear properties of these IASWs are analyzed. It is found that our present plasma model may support compressive as well as rarefactive solitary structures. 相似文献
13.
Weak ion-acoustic (IA) solitary wave propagation is investigated in the presence of electron trapping and background nonextensivity. A physically meaningful distribution is outlined and a Schamel-like equation is derived. The role a background electron nonextensivity may play on the energy carried by the IA soliton is then examined. It is found that nonextensivity may cause a soliton energy depletion. An increase of the amount of electron trapping leads to a net shift towards higher values of the soliton energy. 相似文献
14.
The Kadomtsev-Petviashvili equation in unmagnetized plasma having ions and superthermal electrons and positrons has been derived using the reductive perturbation method. The space-time-fractional Kadomtsev-Petviashvili equation is formulated applying the Euler-Lagrange variational technique and is solved using the sub-equation method. The effects of space time fractional order and superthermal parameters on the properties of obtained soliton have been investigated. 相似文献
15.
Hamid Reza Pakzad Kurosh Javidan Mouloud Tribeche 《Astrophysics and Space Science》2014,352(1):185-191
The propagation of cylindrical and spherical electron acoustic (EA) shock waves in unmagnetized plasmas consisting of cold fluid electrons, hot electrons obeying a superthermal distribution and stationary ions, has been investigated. The standard reductive perturbation method (RPM) has been employed to derive the cylindrical/spherical Korteweg-de-Vries-Burger (KdVB) equation which governs the dynamics of the EA shock structures. The effects of nonplanar geometry, plasma kinematic viscosity and electron suprathermality on the temporal evolution of the cylindrical and spherical EA shock waves are numerically examined. 相似文献
16.
Making use of the Sagdeev pseudo-potential approach, we derive the energy like equation for dust-acoustic (DA) solitary waves in a complex plasma having negatively charged cold dust, and electrons/ions featuring the Tsallis distribution. The effects of electron and ion nonextensivity on the DA soliton profile are examined. It is shown that depending on the strength of particle nonextensivity, our plasma model may admit compressive as well as rarefactive DA solitary waves. Our results complement previously published results on this problem. 相似文献
17.
Electron-acoustic double-layers (EA-DLs) are addressed in a plasma with a q-nonextensive electron velocity distribution. The domain of their allowable Mach numbers depends drastically on the plasma
parameters and, in particular, on the electron nonextensivity. As the electrons evolve far away from their thermodynamic equilibrium,
the negative EA-DLs shrinks and may develop into compressive EA-DLs. Our results may be relevant to the double-layers observed
both in the auroral region and the plasma sheet of Earth’s magnetosphere (during enhanced magnetic activity). These DLs associated
parallel electric fields are thought to be responsible for particle (electrons and ions) acceleration. Furthermore, our theoretical
analysis brings a possibility to develop more refined theories of nonlinear cosmic DLs that may occur in astrophysical plasmas. 相似文献
18.
Weak ion-acoustic double-layers (IA-DLs) in a two-component plasma are investigated in the context of the nonextensive statistics
proposed by Tsallis. Due to the entropic index q, our plasma model can admit compressive as well as rarefactive IA-DLs. It is shown that the values
\frac53 < q < 3\frac{5}{3}q-parameters for the existence of small-DLs. As long as the Mach number M is less than ∼1.42, the only admissible q-values which may lead to IA-DLs are all positive. For −1<q<1 (1<q<5/3), the effect of increasing q is to lower (to shift towards higher values) the critical Mach number M
cr above which only compressive IA-DL are admitted. Beyond q=3, only compressive small-amplitude ion-acoustic double layers are observed. Furthermore, due to the flexibility of the q-parameter, the obtained results bring a possibility to deal with small-DLs with relatively high Mach numbers. Our investigation
may be of wide relevance to astronomers and space scientists working on interstellar plasmas. 相似文献
19.
Nonlinear dynamics of electron-acoustic solitary waves in a magnetized plasma whose constituents are cold magnetized electron fluid, hot electrons featuring Tsallis distribution, and stationary ions are examined. The nonlinear evolution equation (i.e., Zakharov–Kuznetsov (ZK) equation), governing the propagation of EAS waves in such plasma is derived and investigated analytically and numerically, for parameter regimes relevant to the dayside auroral zone. It is revealed that the amplitude, strength and nature of the nonlinear EAS waves are extremely sensitive to the degree of the hot electron nonextensivity. Furthermore, the obtained results are in good agreement with the observations made by the Viking satellite. 相似文献
20.
A weakly nonlinear analysis is carried out to derive a Korteweg–de Vries-Burgers-like equation for small, but finite amplitude,
ion-acoustic waves in a dissipative plasma consisting of weakly relativistic ions, thermal positrons and nonextensive electrons.
The travelling wave solution has been acquired by employing the tangent hyperbolic method. Our results show that in a such
plasma, ion-acoustic shock waves, the strength and steepness of which are significantly modified by relativistic, nonextensive
and dissipative effects, may exist. Interestingly, we found that because of ion kinematic viscosity, an initial solitonic
profile develops into a shock wave. This later evolves towards a monotonic profile (dissipation-dominant case) as the electrons
deviate from their Maxwellian equilibrium. Our investigation may help to understand the dissipative structures that may occur
in high-energy astrophysical plasmas. 相似文献