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1.
On the basis of the three-dimensional elastic inclusion model, the analytic expression of viscoelastic strain field is derived, i.e., the analytic expression of viscoelastic strain at an arbitrary point (x, y, z) in x-axis, y-axis and z-axis produced by three-dimension inclusion in the semi-infinite rheologic medium defined by the standard linear rheologic model, namely the normal strains εxx(r, t), εyy(r, t) and εzz(r, t), the shear strains εxy(r, t) and εyx(r, t), εyz(r, t)and εzy(r, t), εxz(r, t) and εzx(r, t), and the bulk-strain θ (r, t). By computing the spatial-temporal variation of bulk strain on the ground produced by a spherical rheologic inclusion in a semi-infinite rheologic medium, we obtained some significant results that the bulk-strain variation with time produced by a hard inclusion has three stages (α, β,γ) with different characteristics, which are similar to those of most geodetic deformation curves, but not the case for those by a soft inclusion. It is meaningful that these theoretical results have been applied to explain preliminarily the characteristics of stage variation of spatial-temporal evolution, the pattern and quadrant distribution of earthquake precursors, the changeability, spontaneity and complexity of short-term and imminent-term precursors. It offers a theoretical base to found the physical model of earthquake precursors and a reference to predict physically the earthquakes. 相似文献
2.
Introduction Based on the elastic theory of the hard inclusion (Dobrovolskii, 1991), we developed an inclusion theory of rheologic medium, and applied the results of bulk-strain field of a rheologic inclusion model to explain the spatial-temporal evolution process of earthquake precursors (SONG, et al, 2000). In the former paper (SONG, et al, 2003), we derived the viscoelastic displacement field of the rheologic inclusion model on the basis of the analytic expression of displacement field o… 相似文献
3.
Ａｌｉｇｎｍｅｎｔｓｉｌｋｗｏｒｍｓａｓｓｅｉｓｍｉｃａｎｉｍａｌａｎｏｍａｌｏｕｓｂｅｈａｖｉｏｒ（ＳＡＡＢ）ａｎｄｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｍｏｄｅｌｏｆａｆａｕｌｔ：ａｔｈｅｏｒｙａｎｄｌａｂｏｒａｔｏｒｙｅｘｐｅｒｉｍｅｎｔＭＯＴＯ... 相似文献
4.
Based on the three-dimensional ela stic inclusion model proposed by Dobrovolskii, we developed a three-dimensional rheologic
inclusion model and theory to study the earthquake preparation process. By using correspondence principle in the theory of
rheologic mechanics, we derived the analytic expression of the viscoelastic displacement at an arbitrary point (x, y, z) in three directions of x, y and z-axes (i.e., U(r, t), V*(r, t) and W(r, t)) produced by a three-dimension inclusion in the semi-infinite rheologic medium defined by the standard linear rheologic model.
Foundation item: Chinese Joint Seismological Science Foundation (101105) 相似文献
5.
Features and physical process of the dynamic evolution pattern of ground resistivity precursor front
ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅｔｈｅ１９６０′ｓ,ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｍｏｄｅｒｎｓｃｉｅｎｃｅａｎｄｔｅｃｈｎｏｌｏｇｙｈａｓｇｒａｄｕａｌｙｍａｄｅｉｔｐｏｓｉｂｌｅｔｏｐｒｅｄｉｃｔｅａｒｔｈｑｕａｋｅｓａｎｄｈａｓｐｒｏｍｏｔ... 相似文献
6.
7.
ntroductionThe rock medium shows mainly elastic character under low-temperature, low-pressure and external force of short duration, but it shows rheologic property under high-temperature, high-pressure and long-time external force. It is right that rapid earthquake faulting process of only about ten seconds is analyzed by the elastic theory. But for the earthquake generating process continuing over hundreds or thousand years, the rheologic property of rock must be considered (ZHANG, 1987; YI… 相似文献
8.
Early Paleozoic subduction of the Paleo-Asian Ocean: Geochronological and geochemical evidence from the Dashizhai basalts,Inner Mongolia 总被引：10，自引：0，他引：10
Zircon U-Pb results of basalt from the Dashizhai Town in Inner Mongolia, NE China, shows that the basaltic lava was erupted
at 439±3 Ma, much older than the “Permian basalts” as previously thought. These rocks show arc-type trace element patterns
(i.e., Nb-Ta depletion and light REE and large ion lithophile element enrichment) and unradiogenic Sr and highly radiogenic
Nd and Hf isotope compositions. They can be subdivided into two petrogenetic groups: Group 1 basalts have relatively high
TiO2, MgO and compatible elements and low Sr and Th, characterized by mid-oceanic ridge basalt (MORB)-type Sr-Nd-Hf isotope compositions
(87Sr/86Sr(i)=0.7028−0.7032, εNd(t)=+9.8−+11.2, εHf(t)=+16.1−+18.4). Group 2 has lower TiO2, MgO and compatible elements and higher Sr and Th, and relatively evolved Sr-Nd-Hf isotope compositions (87Sr/86Sr(i)=0.7037−0.7038, εNd(t)=+5.7−+7.3, εHf(t)=+12.6−+13.0). Both groups were interpreted as melts derived from a metasomatized mantle wedge formed during the subduction
of Paleo-Asian Ocean. The mantle source for Group 1 was probably a highly isotopically depleted oceanic mantle modified by
predominant slab fluids; whereas subducted sediments had an important contribution to the melting source for Group 2. The
petrogenesis of the Dashizhai basalts provides clear evidence for early Paleozoic subduction of the Paleo-Asian Ocean, and
the highly radiogenic Nd and Hf compositions in these rocks suggest that these lavas and their possible intrusive counterparts
were one of the important components for Phanerozoic crustal growth. Our and previous studies on the “Dashizhai Formation”
volcanic rocks yield an unrealistic eruption range of 440-270 Ma for different rock types, we thus advise to disassemble the
previously defined “Dashizhai Formation” into multiple lithologic units and to reinterpret the spatial and temporal distributions
of different volcano-sedimentary associations.
Supported by National Basic Research Program of China (Grant No. 2006CB403504) 相似文献
9.
D. Caccamo F. Parrillo S. D’Amico F. M. Barbieri C. Laganà 《Izvestiya Physics of the Solid Earth》2007,43(8):662-668
The study of seismic anomalies, related both to the temporal trend of aftershock sequences and to the temporal series of mainshocks,
is important for an understanding of the physical processes relating to the existence and the characteristics of seismic precursors.
The purpose of this work is to highlight some methodological aspects related to the observation of possible anomalies in the
temporal decay of an aftershock sequence. It is realized by means of several parameters. We focused our work on an analysis
of the Papua New Guinea seismic sequence that occurred on November 16, 2000. The magnitude of the mainshock is M = 8.2. The observed temporal series of shocks per day can be considered as a sum of a deterministic contribution and a stochastic
contribution. If the decay can be modeled as a nonstationary Poisson process where the intensity function is equal to n(t) = K(t + c)−p
+ K
1, the number of aftershocks in a small time interval Δt is the mean value n(t)Δt, with a standard deviation σ = √n(t)Δt. We observe that there are some variations in seismicity that can be considered as seismic anomalies before the occurrence
of a large aftershock. The data, checked according to completeness criteria, come from the website of the USGS NEIC data bank
().
The text was submitted by the authors in English. 相似文献
10.
The “earthquake nucleation” is discussed in this paper. The acceleration is a property of the nucleation phase and is a necessary
condition of earthquake instability too. If the acceleration property of this nucleating process is described by the equation
dΘ/dt=C/(t
f−t)
n
, the process can be summarized briefly that the rate of cumulative seismic release is proportional to the inverse power of
the remaining time to failure. Based on this principle, the foreshock sequence of the 1975 Haicheng earthquake withM
S7.3, was analysed backward. It is stated clearly that the time-to-failure and magnitude of the mainshock can be predicted
successfully if the coefficientr
2 attains to the maximum. In the estimation of mainshock time, the error can generally be less than, or far less than, one-half
the remaining time between the time of the last used data point and the mainshock.
Contribution No. 95A0024, Institute of Geophysics, SSB, China.
This study is the "Eighth-Five" contract project ofSSB. 相似文献
11.
Transport of non-ergodic solute plumes by steady-state groundwater flow with a uniform mean velocity, μ, were simulated with Monte Carlo approach in a two-dimensional heterogeneous and statistically isotropic aquifer whose transmissivity,
T, is log-normally distributed with an exponential covariance. The ensemble averages of the second spatial moments of the plume
about its center of mass, <S
i
i
(t)>, and the plume centroid covariance, R
i
i
(t) (i=1,2), were simulated for the variance of Y=log T, σ
Y
2=0.1, 0.5 and 1.0 and line sources normal or parallel to μ of three dimensionless lengths, 1, 5, and 10. For σ
Y
2=0.1, all simulated <S
i
i
(t)>−S
i
i
(0) and R
i
i
(t) agree well with the first-order theoretical values, where S
i
i
(0) are the initial values of S
i
i
(t). For σ
Y
2=0.5 and 1.0 and the line sources normal to μ, the simulated longitudinal moments, <S
11(t)>−S
11(0) and R
11(t), agree well with the first-order theoretical results but the simulated transverse moments <S
22(t)>−S
22(0) and R
22(t) are significantly larger than the first-order values. For the same two larger values of σ
Y
2 but the line sources parallel to μ, the simulated <S
11(t)>−S
11(0) are larger than but the simulated R
11 are smaller than the first-order values, and both simulated <S
22(t)>−S
22(0) and R
22(t) stay larger than the first-order values. For a fixed value of σ
Y
2, the summations of <S
i
i
(t)>−S
i
i
(0) and R
i
i
, i.e., X
i
i
(i=1,2), remain almost the same no matter what kind of source simulated. The simulated X
11 are in good agreement with the first-order theory but the simulated X
22 are significantly larger than the first-order values. The simulated X
22, however, are in excellent agreement with a previous modeling result and both of them are very close to the values derived
using Corrsin's conjecture. It is found that the transverse moments may be significantly underestimated if less accurate hydraulic
head solutions are used and that the decreasing of <S
22(t)>−S
22(0) with time or a negative effective dispersivity, defined as , may happen in the case of a line source parallel to μ where σ
Y
2 is small. 相似文献
12.
You-Kuan Zhang Jie Lin 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(2):117-140
Transport of non-ergodic solute plumes by steady-state groundwater flow with a uniform mean velocity, μ, were simulated with Monte Carlo approach in a two-dimensional heterogeneous and statistically isotropic aquifer whose transmissivity,
T, is log-normally distributed with an exponential covariance. The ensemble averages of the second spatial moments of the plume
about its center of mass, <S
i
i
(t)>, and the plume centroid covariance, R
i
i
(t) (i=1,2), were simulated for the variance of Y=log T, σ
Y
2=0.1, 0.5 and 1.0 and line sources normal or parallel to μ of three dimensionless lengths, 1, 5, and 10. For σ
Y
2=0.1, all simulated <S
i
i
(t)>−S
i
i
(0) and R
i
i
(t) agree well with the first-order theoretical values, where S
i
i
(0) are the initial values of S
i
i
(t). For σ
Y
2=0.5 and 1.0 and the line sources normal to μ, the simulated longitudinal moments, <S
11(t)>−S
11(0) and R
11(t), agree well with the first-order theoretical results but the simulated transverse moments <S
22(t)>−S
22(0) and R
22(t) are significantly larger than the first-order values. For the same two larger values of σ
Y
2 but the line sources parallel to μ, the simulated <S
11(t)>−S
11(0) are larger than but the simulated R
11 are smaller than the first-order values, and both simulated <S
22(t)>−S
22(0) and R
22(t) stay larger than the first-order values. For a fixed value of σ
Y
2, the summations of <S
i
i
(t)>−S
i
i
(0) and R
i
i
, i.e., X
i
i
(i=1,2), remain almost the same no matter what kind of source simulated. The simulated X
11 are in good agreement with the first-order theory but the simulated X
22 are significantly larger than the first-order values. The simulated X
22, however, are in excellent agreement with a previous modeling result and both of them are very close to the values derived
using Corrsin's conjecture. It is found that the transverse moments may be significantly underestimated if less accurate hydraulic
head solutions are used and that the decreasing of <S
22(t)>−S
22(0) with time or a negative effective dispersivity, defined as , may happen in the case of a line source parallel to μ where σ
Y
2 is small. 相似文献
13.
ZhiHong Chen KunYi Guo YongGuan Dong Rong Chen LongMing Li YiHong Liang ChunHai Li XiMing Yu Ling Zhao GuangFu Xing 《中国科学D辑(英文版)》2009,52(7):925-939
We report here geochemical data, U-Pb zircon ages, and Hf isotopes for the high-Mg diorites (HMDs), Nb-enriched basaltic porphyrys
(NEBPs) and plagiogranites (PLAGs) in the Pingshui segment of the Jiangshan-Shaoxing suture zone. The HMDs are characterized
by high Mg# (>60), high Na and LREE contents, depletion of HREE and HFSE, and pronounced positive εNd(t) values of 7.0 to 7.7, similar to some adakitic high-Mg andesites. The NEBPs are relatively Na-rich (Na2O/K2O>6) and display high abundances of P2O5 (∼1.00%), TiO2 (∼3.08%) and HFSE (e.g., Nb=9.53–10.27 ppm). Their Nd isotopic compositions (εNd(t)=6.8–8.0) are comparable to those of the HMDs. The PLAGs are metaluminous (A/CNK=0.84–0.89) and sodic (Na2O/K2O>10). Their depletion in HFSE (e.g., Nb, Ta) is consistent with “SSZ-type” plagiogranite. Zircon LA-ICP-MS U-Pb dating yields
an age of 932±7 Ma for the HMD, 916±6 Ma for the NEBP, and 902±5 Ma for the PLAG, respectively, indicating that they were
products of early Neoproterozoic magmatism. The PLAGs exhibit relatively high zircon Hf isotopes and positive εHf(t) values of 11.0 to 16.2, consistent with their Nd isotopic data (εNd(t)=7.5–8.4). Such features are similar to those of oceanic plagiogranites in ophiolites and distinct from those of crust-derived
granites. The PLAGs were most likely derived from partial melting of subducted oceanic crust in an active continental margin.
Considering these results in the context of the regional geology, we suggest that a slab window in the subducting oceanic
crust between the Yangtze Block and Cathaysia Block was possibly the principal cause for the unique arc magmatism in the area.
The upwelling asthenosphere below the slab window may have provided significant thermodynamic conditions.
Supported by China Geological Survey (Grant No. 1212010610611) and the Ministry of Land and Resources (Grant No. 200811015) 相似文献
14.
Prediction of rockburst probability given seismic energy and factors defined by the expert method of hazard evaluation (MRG) 总被引：2，自引：0，他引：2
In this paper we suggest that conditional estimator/predictor of rockburst probability (and rockburst hazard, P
T
(t)) can be approximated with the formula P
T
(t) = P
1(θ
1)…P
N
(θ
N
)·P
dyn
T
(t), where P
dyn
T
(t) is a time-dependent probability of rockburst given only the predicted seismic energy parameters, while P
i
(θ
i
) are amplifying coefficients due to local geologic and mining conditions, as defined by the Expert Method of (rockburst)
Hazard Evaluation (MRG) known in the Polish mining industry. All the elements of the formula are (approximately) calculable
(on-line) and the resulting P
T
value satisfies inequalities 0 ≤ P
T
(t) ≤ 1. As a result, the hazard space (0–1) can be always divided into smaller subspaces (e.g., 0–10−5, 10−5–10−4, 10−4–10−3, 10−3–1), possibly named with symbols (e.g., A, B, C, D, …) called “hazard states” — which saves the prediction users from worrying of probabilities. The estimator P
T
can be interpreted as a formal statement of (reformulated) Comprehensive Method of Rockburst State of Hazard Evaluation,
well known in Polish mining industry. The estimator P
T
is natural, logically consistent and physically interpretable. Due to full formalization, it can be easily generalized, incorporating
relevant information from other sources/methods. 相似文献
15.
Shallow water tidal currents in close proximity to the seafloor and boundary-induced turbulence 总被引：1，自引：0，他引：1
Iossif Lozovatsky Zhiyu Liu Harindra Fernando Jordi Armengol Elena Roget 《Ocean Dynamics》2012,62(2):177-191
Velocity measurements with vertical resolution 0.02 m were conducted in the lowest 0.5 m of the water column using acoustic
Doppler current profiler (ADCP) at a test site in the western part of the East China Sea. The friction velocity u
* and the turbulent kinetic energy dissipation rate ε
wl(ζ) profiles were calculated using log-layer fits; ζ is the height above the bottom. During a semidiurnal tidal cycle, u
* was found to vary in the range (1–7) × 10−3 m/s. The law-of-the-wall dissipation profiles ε
wl(ζ) were consistent with the dissipation profiles ε
mc(ζ) evaluated using independent microstructure measurements of small-scale shear, except in the presence of westward currents.
It was hypothesized that an isolated bathymetric rise (25 m height at a 50-m seafloor) located to the east of the measurement
site is responsible for the latter. Calculation of the depth integrated internal tide generating body force in the region
showed that the flanks of the rise are hotspots of internal wave energy that may locally produce a significant turbulent zone
while emitting tidal and shorter nonlinear internal waves. This distant topographic source of turbulence may enhance the microstructure-based
dissipation levels ε
mc(ζ) in the bottom boundary layer (BBL) beyond the dissipation ε
wl(ζ) associated with purely locally generated turbulence by skin currents. Semi-empirical estimates for dissipation at a distance
from the bathymetric rise agree well with the BBL values of ε
mc measured 15 km upslope. 相似文献
16.
V. V. Bogdanov A. V. Pavlov A. L. Polyukhova 《Journal of Volcanology and Seismology》2010,4(6):412-422
The catalog of Kamchatka earthquakes is represented as a probability space of three objects {Ω, $
\tilde F
$
\tilde F
P}. Each earthquake is treated as an outcome ω
i
in the space of elementary events Ω whose cardinality for the period under consideration is given by the number of events.
In turn, ω
i
is characterized by a system of random variables, viz., energy class ki, latitude φ
i
, longitude λ
i
, and depth h
i
. The time of an outcome has been eliminated from this system in this study. The random variables make up subsets in the set
$
\tilde F
$
\tilde F
and are defined by multivariate distributions, either by the distribution function $
\tilde F
$
\tilde F
(φ, λ, h, k) or by the probability density f(φ, λ, h, k) based on the earthquake catalog in hand. The probabilities P are treated in the frequency interpretation. Taking the example of a recurrence relation (RR) written down in the form of
a power law for probability density f(k), where the initial value of the distribution function f(k
0) is the basic data [Bogdanov, 2006] rather than the seismic activity A
0, we proceed to show that for different intervals of coordinates and time the distribution f
elim(k) of an earthquake catalog with the aftershocks eliminated is identical to the distribution f
full(k), which corresponds to the full catalog. It follows from our calculations that f
0(k) takes on nearly identical numeral values for different initial values of energy class k
0 (8 ≤ k
0 ≤ 12) f(k
0). The difference decreases with an increasing number of events. We put forward the hypothesis that the values of f(k
0) tend to cluster around the value 2/3 as the number of events increases. The Kolmogorov test is used to test the hypothesis
that statistical recurrence laws are consistent with the analytical form of the probabilistic RR based on a distribution function
with the initial value f(k
0) = 2/3. We discuss statistical distributions of earthquake hypocenters over depth and the epicenters over various areas for
several periods 相似文献
17.
The source parameters of the M
W
= 7.6 Olyutorskii earthquake were estimated using the moments of the slip rate function with degrees 1 and 2. The moments
were estimated from broadband P-wave records at 52 stations of the worldwide network. The first step was to find a function S(t) for each station; this function is an apparent source time function, i.e., the P-wave slip as radiated by the source toward a station under consideration. The method of empirical Green’s functions was used
to estimate S(t). The next step was to calculate the moments of S(t) of degrees 1 and 2 over time and to set up relevant equations to be solved by least squares for the unknown source moments.
The horizontal linear source was used as a nonparametric model for calculating the source moments. Haskell’s parametric model
was used for further interpretation of the source moments. The resulting estimates are as follows: the source centroid was
13–25 km southwest of the epicenter, the source was 105–120 km long, the source strike was 222°–228°, the rupture velocity
was 2.7–3.0 km/s, and the total radiation duration was 24–27 s. These estimates indicate a bilateral rupture dominated by
a southwestward sense of rupture propagation. The source characteristics are consistent with the aftershock area geometry
and with the focal mechanism, as well as with surface breakage as observed by geologists in the field. 相似文献
18.
19.
Tunnel effect of fractal fault and transient S-wave velocity rupture (TSVR) of in-plane shear fault 总被引：1，自引：0，他引：1
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20.
It is shown that within the framework of the Kolmogorov model the “energy” of the pole E(t) = x
12 + x
22 can be interpreted as a Markovian process. The exact analytical expression has been obtained for the density of the conditional
probability of the quantity E(t) and the problem of the first passage time of the process E(t) has been analyzed. It was shown that the available data on the swing of the function E(t) are not at variance with the Kolmogorov model and a short-period drop of the amplitude of the Chandler wobble in the early
20th century fits this model at Q = 50–200 too; values of Q > 350 are less reasonable. 相似文献