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1.
In this study, observed seismic attributes from shot gather 11 of the SAREX experiment are used to derive a preliminary velocity and attenuation model for the northern end of the profile in southern Alberta. Shot gather 11 was selected because of its prominent Pn arrivals and good signal to noise ratio. The 2-D Gaussian beam method was used to perform the modeling of the seismic attributes including travel times, peak envelope amplitudes and pulse instantaneous frequencies for selected phases. The preliminary model was obtained from the seismic attributes from shot gather 11 starting from prior tomographic results. The amplitudes and instantaneous frequencies were used to constrain the velocity and attenuation structure, with the amplitudes being more sensitive to the velocity gradients and the instantaneous frequencies more sensitive to the attenuation structure. The resulting velocity model has a velocity discontinuity between the upper and lower crust, and lower velocity gradients in the upper and lower crust compared to earlier studies. The attenuation model has Q p -1 values between 0.011 and 0.004 in the upper crust, 0.0019 in the lower crust and a laterally variable Q p -1 in the upper mantle. The Q p -1 values are similar to those found in Archean terranes from other studies. Although the results from a single gather are non-unique, the initial model derived here provides a self-consistent starting point for a more complete seismic attribute inversion for the velocity and attenuation structure.  相似文献   

2.
We construct and evaluate a new three-dimensional model of crust and upper mantle structure in Western Eurasia and North Africa (WENA) extending to 700 km depth and having 1° parameterization. The model is compiled in an a priori fashion entirely from existing geophysical literature, specifically, combining two regionalized crustal models with a high-resolution global sediment model and a global upper mantle model. The resulting WENA1.0 model consists of 24 layers: water, three sediment layers, upper, middle, and lower crust, uppermost mantle, and 16 additional upper mantle layers. Each of the layers is specified by its depth, compressional and shear velocity, density, and attenuation (quality factors, Q P and Q S ). The model is tested by comparing the model predictions with geophysical observations including: crustal thickness, surface wave group and phase velocities, upper mantle n velocities, receiver functions, P-wave travel times, waveform characteristics, regional 1-D velocities, and Bouguer gravity. We find generally good agreement between WENA1.0 model predictions and empirical observations for a wide variety of independent data sets. We believe this model is representative of our current knowledge of crust and upper mantle structure in the WENA region and can successfully be used to model the propagation characteristics of regional seismic waveform data. The WENA1.0 model will continue to evolve as new data are incorporated into future validations and any new deficiencies in the model are identified. Eventually this a priori model will serve as the initial starting model for a multiple data set tomographic inversion for structure of the Eurasian continent.  相似文献   

3.
This paper deals with characteristics of the short period S-wave attenuation field in the rupture zones of 37 large and great earthquakes with M s = 7.0–8.6, as well as in low seismicity areas. We estimate the effective quality factor from Sn and Lg coda envelopes in two time intervals (Q 1 and Q 2). The quantity Q 1 is a measure of shear wave attenuation in the uppermost mantle, at depths of down to approximately 200–250 km, while Q 2 is relevant to deeper horizons of the upper mantle. We studied variations in the attenuation field in the rupture zone of the 1950 Assam earthquake. We examined the parameters Q 1, Q 2, and Q 1/Q 2 as functions of the time ΔT elapsed after a large earthquake. It is shown that the parameter Q 2 in rupture zones is practically independent of ΔT, while the quantities Q 1 and Q 1/Q 2 increase until ΔT ～ 20–25 years, especially rapidly for normal, normal-oblique, and strike-slip earthquake mechanisms. This analysis provides evidence that, as ΔT increases, so does the quality factor in the upper mantle for shear waves. It is supposed that this is related to the rise of mantle fluids to the crust. Geodynamic mechanisms are discussed that can support a comparatively rapid “drying” of the upper mantle beneath earthquake rupture zones.  相似文献   

4.
Based on the long period surface wave data recorded by the China Digital Seismograph Network (CDSN), theQ R of fundamental mode Rayleigh wave with periods from 10 s to 146 s is determined for the eastern Sino-Korean paraplatform in this paper. TheQ β models of the crust and upper mantle are respectively obtained for the 4 paths, with the aid of stochastic inverse method. It shows that in the eastern Sino-Korean paraplatform, the average crustalQ β is about 200, and that there exists a weak attenuation layer in the middle crust (about 10–20 km deep) which is possibly related to earthquake-prone layer. A strong attenuation layer (lowQ) of 70 km thick extensively exists in the uppermost mantle, with the buried depth about 80 km. The averageQ R of fundamental mode Rayleigh wave is between the value of stable tectonic region and that of active tectonic region, and much close to the latter.  相似文献   

5.
We employ a niching genetic algorithm to invert ∼30,000 differential ScS/S attenuation values for a new spherically symmetric radial model of shear quality factor (Qμ) with high sensitivity to the lower mantle. The new radial Qμ model, QLM9, possesses greater sensitivity to Qμ at large mantle depths than previous studies. On average, lower mantle Qμ increases with depth, which supports models of increasing viscosity with depth [B.M. Steinberger, A.R. Calderwood. Mineral physics constraints on viscous flow models of mantle flow, J. Conf. Abs., 6, 2001., 2001.]. There are two higher-Qμ regions at ∼1000 and ∼2500 km depth, which roughly correspond to high-viscosity regions observed by Forte and Mitrovica [A.M. Forte and J.X. Mitrovica, Deep-mantle high-viscosity flow and thermochemical structure inferred from seismic and geodynamic data, Nature 410, 1049–1056, 2001.]. There is a lower-Qμ layer at the core–mantle boundary and a relatively low-Qμ region in the mid-lower mantle. With several caveats, we infer a divergence of the solidus and geotherm in the lower mantle and a convergence within Dʺ by relating Qμ to homologous temperature.  相似文献   

6.
Rayleigh wave attenuation is investigated for periods ranging from 20 to 90 s, along a 450 km-long profile following the Oligocene tensile zone of the French Massif Central. A model is deduced by inversion, assuming that the S-wave intrinsic quality factor Qβ is frequency-independent, and yields a mean value Qβ = 43 ± 10 for the first 100 km in the upper mantle. This value, far lower than the mean value obtained in Eurasia, is close to those obtained in other recent tensile areas, e.g., the western United States or mid-oceanic ridges.A velocity-depth model for S-waves, deduced in a previous study from surface-wave propagation, has been corrected for the attenuation effect. We find a discrepancy between the corrected S-model and P-wave residuals in the same area, implying that Qβ must be frequency-dependent. This can be a clue for partial melting in the upper mantle beneath this region.  相似文献   

7.
Average shear-velocity models for the upper mantle have been derived by controlled Monte Carlo inversion of global average Rayleigh wave group velocity (GAGV) data for periods between 50 and 300 seconds. GAGV data have been corrected for attenuative dispersion using a method based on the theory of Liu, Anderson and Kanamori. Two types of model bounds have been used with one- or two-layer low-velocity zones beginning at depths of 70 and 100 km. All models fitting GAGV data within one standard deviation have low-velocity zones in the 100–200 km depth range. Models with low-velocity zones beginning at 70 km, as well as 100 km, fit GAGV data within one standard deviation, so the average thickness of the lithosphere (taken as the depth to the top of the low-velocity zone) cannot be determined with precision.Global average models for shear-wave attenuation (Q?1β) have been derived from global average Rayleigh wave attenuation coefficients for periods between 50 and 300 s and average shear-velocity models. Zones of high Q?1β coincide with the low-velocity zones of all shear-velocity models, however, models with low-velocity zones beginning at a depth of 70 km have the highest-attenuation layer in the lower half of the low-velocity zone. Resolution kernels for these attenuation models show that parameters for layers shallower than the lower part of the low-velocity-high-attenuation zone are strongly coupled but are distinct from the lower part of this zone. This suggests that the deeper part of the low-velocity-high-attenuation zone is the most mobile part of the zone or that on the average, the top of the zone is deeper than 70 km.The average Qβ of the lithosphere, low-velocity zone, and sub-low-velocity layer (asthenosphere) are approximately 200, 85–110 and 170–200, respectively.  相似文献   

8.
36 pairs of multiply-reflected ScS waves from deep earthquakes around Japan are analyzed to investigate the anelastic properties of the mantle on the continental and oceanic sides of the dipping slab. The average Q-value for shear waves passing through the mantle on the oceanic side is found to be 226 in the frequency range 10–40 mHz. This Q-value is in good agreement with the Q models SL8 (Anderson and Hart, 1978) and QBS (Sailor and Dziewonski, 1978) which have been derived from free oscillation data. Assuming that the Q-value for the mantle deeper than 400 km on the continental side of the Japanese Arc is the same as that for the model SL8, we obtain a value of Q = 53 in the upper mantle above the dipping slab beneath the Sea of Japan. Higher Q-values are obtained for the mantle behind the northern Izu-Bonin arc.  相似文献   

9.
On the basis of data of long period Rayleigh surface wave, we select 43 two-station paths which cover the eastern China thoroughly. By using the improved method of multi-filtration, we obtain the group velocity and amplitude spectrum, and then get attenuation factor for each paths. We employ Talentola inversion method to get local attenuation factor, and further invert the three-dimension Q β image under the crust and upper mantle in the eastern Chinese continent. The Q β image shows the following basic characters. There is correlation between the seismic activity and Q β structure under the crust and upper mantle in North China region. The Yangtze block begins to collide with and subduct to the North China block from the southern border of the Qinling in the southern Shaanxi. In the large part of Yangtze quasi-platform appear an obvious high Q β area at 88 km deep. In the east of Sichuan depression platform, the juncture of Sichun and Guizhou, and the Jiangnan block near the juncture of Guizhou and Hunan, the lateral variation of Q β in the crust is little, and there is a high-Q β layer no thinner than 40 km in the top mantle. In the Dian-Qian fold and fracture region between Yunnan and Guizhou, the vertical variation of Q β at the region of the crust and upper mantle is little, there is a low-Q β layer in the top mantle, about 40 km thick, low-Q β layer of the upper mantle begins to appear at about 95 km deep. In the east of Yangtze quasi-platform and the central and eastern part of the South China fold system, the Moho is smooth, the lateral variation of Q β in the crust is also little, low-Q β layer of the upper mantle begins to appear at about 85 km deep.  相似文献   

10.
—Observed velocities and attenuation of fundamental-mode Rayleigh waves in the period range 7–82 sec were inverted for shear-wave velocity and shear-wave Q structure in the Middle East using a two-station method. Additional information on Q structure variation within each region was obtained by studying amplitude spectra of fundamental-mode and higher-mode Rayleigh waves. We obtained models for the Turkish and Iranian Plateaus (Region 1), areas surrounding and including the Black and Caspian Seas (Region 2), and the Arabian Peninsula (Region 3). The effect of continent-ocean boundaries and mixed paths in Region 2 may lead to unrealistic features in the models obtained there. At lower crustal and upper-mantle depths, shear velocities are similar in all three regions. Shear velocities vary significantly in the uppermost 10 km of the crust, being 3.21, 2.85, and 3.39 km/s for Regions 1, 2, and 3, respectively. Q models obtained from an inversion of interstation attenuation data show that crustal shear-wave Q is highest in Region 3 and lowest in Region 1. Q’s for the upper 10 km of the crust are 63, 71, and 201 for Regions 1, 2, and 3, respectively. Crustal Q’s at 30 km depth for the three regions are about 51, 71, and 134. The lower crustal Q values contrast sharply with results from stable continental regions where shear-wave Q may reach one thousand or more. These low values may indicate that fluids reside in faults, cracks, and permeable rock at lower crustal, as well as upper crustal depths due to convergence and intense deformation at all depths in the Middle Eastern crust.  相似文献   

11.
A two dimensional velocity model of the upper mantle has been compiled from a long-range seismic profile crossing the West Siberian young plate and the old Siberian platform. It revealed considerable horizontal and vertical heterogeneity of the mantle. A sharp seismic boundary at a depth of 400 km outlines the high-velocity gradient transition zone, its base lying at a depth of 650 km. Several layers with different velocities, velocity gradients and wave attenuation are distinguished in the upper mantle. They likewise differ in their inner structure. For instance, the uppermost 50–70 km of the mantle are divided into blocks with velocities from 7.9–8.1 to 8.4–8.6 km s?1.Comparison of the travel-time curves for the Siberian long-range profile with those compiled from seismological data for Europe distinguished large-scale upper mantle inhomogeneities of the Eurasian continent and allowed for the correlation of tectonic features and geophysical fields. The velocity heterogeneity of the uppermost 50–100 km of the mantle correlates with the platform age and heat flow, i.e., the young plates of Western Europe and Western Siberia have slightly lower velocities and higher heat flows than the ancient East European and Siberian platforms. At greater depths (150–250 km) the upper mantle velocities increase from the ocean to the inner parts of the continent. The structure of the transition zone differs significantly beneath Western Europe and the other parts of Eurasia. The sharp boundary at a depth of 400 km, traced throughout the whole continent as the boundary reflecting intensive waves, transforms beneath Western Europe into a gradient zone. This transition zone feature correlates with positions of the North Atlantic-west Europe geoid and heat-flow anomalies.  相似文献   

12.
—?The digital data acquired by 16 short-period seismic stations of the Friuli-Venezia-Giulia seismic network for 56 earthquakes of magnitude 2.3–4.7 which occurred in and near NE Italy have been used to estimate the coda attenuation Q c and seismic source parameters. The entire area under study has been divided into five smaller regions, following a criterion of homogeneity in the geological characteristics and the constrains imposed by the distribution of available events. Standard IASPEI routines for coda Q c determination have been used for the analysis of attenuation in the different regions showing a marked anomaly in the values measured across the NE border between Friuli and Austria for Q 0 value. A large variation exists in the coda attenuation Q c for different regions, indicating the presence of great heterogeneities in the crust and upper mantle of the region. The mean value of Q c (f) increases from 154–203 at 1.5?Hz to 1947–2907 at 48?Hz frequency band with large standard deviation estimates.¶Using the same earthquake data, the seismic-moment, M 0, source radius, r and stress-drop, Δσ for 54 earthquakes have been estimated from P- and S-wave spectra using the Brune's seismic source model. The earthquakes with higher stress-drop (greater than 1?Kbar) occur at depths ranging from 8 to 14?km.  相似文献   

13.
The fundamental mode Love and Rayleigh waves generated by ten earthquakes and recorded across the Tibet Plateau, at QUE, LAH, NDI, NIL, KBL, SHL, CHG, SNG and HKG are analysed. Love- and Rayleigh-wave attenuation coefficients are obtained at time periods of 5–120 s using the spectral amplitudes of these waves for 23 different paths. Love wave attenuation coefficient varies from 0.0021 km?1, at a period of 10 s, to 0.0002 km?1 at a period of 90 s, attaining two maxima at time periods of 10 and 115 s, and two minima at time periods of 25 and 90 s. The Rayleigh-wave attenuation coefficient also shows a similar trend. The very low value for the dissipation factor, Qβ, obtained in this study suggests high dissipation across the Tibetan paths. Backus-Gilbert inversion theory is applied to these surface wave attenuation data to obtain average Qβ?1 models for the crust and uppermost mantle beneath the Tibetan Plateau. Independent inversion of Love- and Rayleigh-wave attenuation data shows very high attenuation at a depth of ～50–120 km (Qβ ? 10). The simultaneous inversion of the Love and Rayleigh wave data yields a model which includes alternating regions of high and low Qβ?1 values. This model also shows a zone of high attenuating material at a depth of ～40–120 km. The very high inferred attenuation at a depth of ～40–120 km supports the hypothesis that the Tibetan Plateau was formed by horizontal compression, and that thickening occurred after the collision of the Indian and Eurasian plates.  相似文献   

14.
Long-range seismic sounding carried out during the last few years on the territory of the U.S.S.R. has shown a basic inhomogeneity of the uppermost mantle, as well as evidence of regularities in the distribution of its seismic parameters. The following data were used: times and apparent velocities of P- and S-waves for investigation of mantle velocities, converted waves for seismic discontinuity model studies and wave attenuation for Q-factor estimation. Strong regularities were distinguished in the distribution of average seismic velocities for the uppermost mantle, in their dependence on the age and type of geostructure and on their position relative to the central part of the continent. Old platforms and the inner part of the continent are marked by velocities under the Mohorovi?i? discontinuity of more than 8.2–8.3 km s?1, young platforms and outer parts of the continent by 8.0–8.2 km s?1, and orogenic and rift zones by 7.8–8.0 km s?1. The difference becomes more pronounced at a depth of about 100–200 km: for the old platform mantle velocities of 8.5–8.6 km s?1 are typical; beneath the orogenic and rift areas, inversion zones with velocities less than 7.8 km s?1 are observed.The converted waves show fine inhomogeneities of the crust and uppermost mantle, the presence of many discontinuities with positive and negative changes of velocity, and anisotropy of seismic waves in some of the layers. Wave attenuation allowed the determination of the Q-factor in the mantle. It varied from one region to another but a close relation between Q and P-wave velocity is the main cause of its variation.  相似文献   

15.
The quality factor Q as a function of frequency in an S wave range of 1–8 Hz is estimated from records of ～60 earthquakes (M w > 3.9 and source depths of 1–60 km) obtained at the Sochi seismic station at epicentral distances of less than ～300 km. Methods of Q estimation used in the paper were developed in works by Aki, Rautian, and others; they are based on the suppression of source-related and local effects in S wave spectra with the help of coda waves measured at a fixed time from the first arrival. To compensate for directivity effects, averaging was performed over the set of events whose sources were located in a wide range of back azimuths. The geometric divergence is represented as a three-segment function: 1/R, 1, and 1/√R at epicentral distances of 1/50–1/70 to 50–70 km, 50–70 to 130–150 km, and greater than 130–150 km, respectively. The geometric divergences in this model yielded the following estimates of the quality factor: Q(f) ～ 80f 0.9 with a base of 35–280 km and Q(f) ～ 110f 0.8 with a base of 60–280 km. The resulting combinations of the propagation path effects (Q and the geometric divergence) can be used for predicting strong motion parameters in the Northern Caucasus.  相似文献   

16.
—Records from broadband digital stations have allowed us to map regional variations of Lg coda Q across almost the entire United States. Using a stacked ratio method we obtained estimates of Q 0 (Lg coda Q at 1 Hz) and its frequency dependence, <eta>, for 218 event-station pairs. Those sets of estimates were inverted using a back-projection method to obtain tomographic images showing regional variations of Q 0 and <eta>. Q 0 is lowest (250–300) in the California coastal regions and the western part of the Basin and Range province, and highest (650–750) in the northern Appalachians and a portion of the Central Lowlands. Intermediate values occur in the Colorado Plateau (300–500), the Columbia Plateau (300–400), the Rocky Mountains (450–550), the Great Plains (500–650), the Gulf Coastal Plain and the southern portion of Atlantic Coastal Plain (400–500), and the portions of the Central Lowlands surrounding the high-Q region (500–550). The pattern of Q 0 variations suggests that the United States can be divided into two large Q provinces. One province spans the area from the Rocky Mountains to the Atlantic coast, is tectonically stable, and exhibits relatively high Q 0?. The other extends westward from the approximate western margin of the Rocky Mountains to the Pacific coast, is tectonically active, and exhibits low Q 0?. The transition from high to low Lg coda Q in the western United States lies further to the west than does an upper mantle transition for Q and electrical resistivity found in earlier studies. The difference in Q 0 between the western and eastern United States can be attributed to a greater amount of interstitial crustal fluids in the west. Regions of moderately reduced Q within the stable platform often occur where there are accumulations of Mesozoic and younger sediments. Reduced Q 0 in the southeastern United States may not be due to anelasticity but may rather be explained by a gradational velocity increase at the crust-mantle boundary that causes shear energy to leak into the mantle.  相似文献   

17.
Multi-phase long-period t* measurements are among the key evidences for the frequency-dependent mantle attenuation factor, Q. However, similarly to Q, poorly constrained variations of Earth’s structure may cause spurious frequency-dependent effects in the observed t*. By using an attenuation-coefficient approach which incorporates measurements of geometric spreading (GS), such effects can be isolated and removed. The results show that the well-known increase of body P-wave t* from ~0.2 s at short periods to ~1–2 s at long periods may be caused by a small and positive bias in the underlying GS, which is measured by a dimensionless parameter γ*?≈?0.06. Similarly to the nearly constant t* at teleseismic distances, this GS bias is practically range-independent and interpreted as caused by velocity heterogeneity within the crust and uppermost mantle. This bias is accumulated within a relatively thin upper part of the lithosphere and may be closely related to the crustal body-wave GS parameter γ?~?4–60 mHz reported earlier. After a correction for γ, P-wave t P * becomes equal ~0.18 s at all frequencies. By using conventional dispersion relations, this value also accounts for ~40 % of the dispersion-related delay in long-period travel times. For inner-core attenuation, the attenuation coefficient shows a distinctly different increase with frequency, which is remarkably similar to that of fluid-saturated porous rock. As a general conclusion, after the GS is accounted for, no absorption-band type or frequency-dependent upper-mantle Q is required for explaining the available t* and velocity dispersion observations. The meaning of this Q is also clarified as the frequency-dependent part of the attenuation coefficient. At the same time, physically justified theories of elastic-wave attenuation within the Earth are still needed. These conclusions agree with recent re-interpretations of several surface, body and coda-wave attenuation datasets within a broad range of frequencies.  相似文献   

18.
The Q-factor estimates of the Earth’s crust and upper mantle as the functions of frequency (Q(f)) are obtained for the seismic S-waves at frequencies up to ~35 Hz. The estimates are based on the data for ~40 earthquakes recorded by the Kislovodsk seismic station since 2000. The magnitudes of these events are MW > 3.8, the sources are located in the depth interval from 1 to 165 km, and the epicentral distances range from ~100 to 300 km. The Q-factor estimates are obtained by the methods developed by Aki and Rautian et al., which employ the suppression of the effects of the source radiation spectrum and local site responses in the S-wave spectra by the coda waves measured at a fixed lapse time (time from the first arrival). The radiation pattern effects are cancelled by averaging over many events whose sources are distributed in a wide azimuthal sector centered at the receiving site. The geometrical spreading was specified in the form of a piecewise-continuous function of distance which behaves as 1/R at the distances from 1 to 50 km from the source, has a plateau at 1/50 in the interval from 50–70 km to 130–150 km, and decays as \({\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 {\sqrt R }}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${\sqrt R }$}}\) beyond 130–150 km. For this geometrical spreading model and some of its modifications, the following Q-factor estimates are obtained: Q(f) ~ 85f0.9 at the frequencies ranging from ~1 to 20 Hz and Q(f) ~ 75f1.0 at the frequencies ranging from ~1 to 35 Hz.  相似文献   

19.
Pure-path averages for group velocities and specific attenuation have been calculated from individual observations and from path averages for two regionalizations; one original to this study and the other previously devised by Wu. Both are based on four upper-mantle provinces: ocean basin, continent, island arc and mid-ocean ridge. Pure-path group velocities and specific attenuation have also been calculated for combinations of regions and provide well separated regional measurements for such composite regions.Shear-velocity models for pure and combined regions have been derived by a controlled Monte Carlo inversion procedure and indicates that a low-velocity zone is required beneath the oceans, but is not required beneath continents. Models have been produced for pure and combined ocean, ocean-ridge, continent and continent-arc provinces.Q?1R determined from pure-path average group velocities and attenuation coefficients has been regionalized successfully for 2- and 3-region combinations. The resulting pure-path Q?1R for continents is much lower than that for ocean basins and ocean-ridge provinces. Inversion of Q?1R for ocean-ridge provinces shows that the average Qβ for the upper 200 km of these regions is between 85 and 100.  相似文献   

20.
Based on the Anapa (ANN) seismic station records of ~40 earthquakes (MW > 3.9) that occurred within ~300 km of the station since 2002 up to the present time, the source parameters and quality factor of the Earth’s crust (Q(f)) and upper mantle are estimated for the S-waves in the 1–8 Hz frequency band. The regional coda analysis techniques which allow separating the effects associated with seismic source (source effects) and with the propagation path of seismic waves (path effects) are employed. The Q-factor estimates are obtained in the form Q(f) = 90 × f 0.7 for the epicentral distances r < 120 km and in the form Q(f) = 90 × f1.0 for r > 120 km. The established Q(f) and source parameters are close to the estimates for Central Japan, which is probably due to the similar tectonic structure of the regions. The shapes of the source parameters are found to be independent of the magnitude of the earthquakes in the magnitude range 3.9–5.6; however, the radiation of the high-frequency components (f > 4–5 Hz) is enhanced with the depth of the source (down to h ~ 60 km). The estimates Q(f) of the quality factor determined from the records by the Sochi, Anapa, and Kislovodsk seismic stations allowed a more accurate determination of the seismic moments and magnitudes of the Caucasian earthquakes. The studies will be continued for obtaining the Q(f) estimates, geometrical spreading functions, and frequency-dependent amplification of seismic waves in the Earth’s crust in the other regions of the Northern Caucasus.  相似文献   

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