bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of the transmitted Kirchhoff-Holmholtz method to transmitted body waves and possible structural effects at NTS
Authors: Scott Patricia , Helmberger Donald V.
Published: July 2021

We extend the Kirchhoff-Helmholtz integral method to calculate acoustic potentials which transmit through three-dimensional warped boundaries. We specify the potentials on an arbitrary surface with Snell's law and plane-wave transmission coefficients and numerically integrate their contributions at a receiver via the scalar integral representation theorem. The method is appropriate for modeling precritical transmitted potentials. Results from test models compare well with optical solutions for transmissions through a flat interface. We model the effect of several idealized crust-mantle boundary structures on teleseismic P wave generated by explosion sources. The structures are all upwarps and are designed to produce travel-time residuals as a function of delta and azimuth which have the same magnitude as residuals observed for NTS tests within Pahute Mesa. These structures consistently cause complicated low amplitude waveforms which arrive early and simple high amplitude waveforms which arrive late. Thus, they cause systematic amplitude variations with azimuth, delta, and source location. The magnitude of this variation is less than or equal to 212. This factor is somewhat less than the observed ab amplitude variation with azimuth of Pahute Mesa tests; however, it is approximately the same magnitude as the observed ab variation at a given station as a function of test location within the mesa.
The two-dimensional resonance of sediment-filled valleys
Authors: Bard Pierre-Yves , Bouchon Michel
Published: July 2021

This paper presents a numerical study of the response of relatively embanked sediment-filled valleys to incident plane SH, SV, and P waves, in the two-dimensional case. The Aki-Larner technique used here is shown to be reliable even for steep interface slopes. Numerical results show the existence and the importance in such valleys of specific two-dimensional resonance patterns, which may be classified in three categories: the antiplane shear modes, corresponding to SH motion; the in-plane shear modes (SV); and the in-plane bulk modes (P). Each of them is characterized by the consistency of the peak frequencies, and the in-phase motion (modulo 180°) across the whole valley. They induce a very large amplification, even in the case of significant damping (up to 4 times the corresponding one-dimensional prediction), a very long duration of motion, and large differential motion. The characteristics of the fundamental modes are in good qualitative agreement with the relevant experimental observations. The existence of this two-dimensional resonance is controlled by the shape ratio (thickness to half-width ratio) and the velocity contrast: a quantitative relationship is proposed in the SH case. The frequency of these resonance modes, for each pattern, is shown to depend only on two parameters: the one-dimensional resonance frequency at the valley center and the shape ratio. A simple model of a soft rectangular inclusion is shown to provide satisfactory quantitative formulas to estimate the fundamental resonance frequencies of any valley. As to the amplitude of this two-dimensional resonance, the general trends of its dependence on the different valley parameters (shape ratio, velocity contrast, Poisson ratio, damping) and on the incident wave field characteristics (wave type, incidence angle) are indicated. An important result, however, for earthquake engineering purposes is that both the two-dimensional resonant frequencies and amplification values differ a lot from their “classical” one-dimensional estimates.
Attenuation of intensities and effect of local site conditions on observed intensities during the Corinth, Greece, earthquakes of 24 and 25 February and 4 March 1981
Authors: Tilford N. R. , Chandra Umesh , Amick D. C. , Moran R. , Snider F.
Published: July 2021

Field investigations conducted immediately after the Gulf of Corinth earthquake of 24 February 1981 provide an extensive set of data on intensity at different sites for the main shock and two of its principal aftershocks. Each site of intensity observation was characterized by the local site geologic condition. The hypocenters of the three shocks were relocated by using the joint epicenter location technique, with the aftershock of 12 March, 1981 (01:49 UTC), recorded by six portable stations as well as stations of the Greek National Seismographic Network, as the calibration event. Isoseismal maps prepared by using all intensity data for the three shocks were used to derive new attenuation relations. Analysis of the intensity residuals (observed-calculated intensity) shows that local site geologic condition has a significant effect on the intensity observed at a site. On an average, under similar circumstances, sites located on soil foundations experience about one intensity unit more shaking than sites located on rock foundations. Likewise, sites located on Neogene sediments (intermediate foundation condition) experience about 12 unit greater intensity effect than sites located on rock foundations. Attenuation relations derived by using intensity data for the three February-March 1981 earthquakes show lower attenuation than the relation derived by using published isoseismal maps for 19 earthquakes which occurred in the Corinth-Saronikos region during 1861 to 1975.
A strategy for deploying a seismological network for global studies of Earth structure
Authors: Souriau Annie , Woodhouse J. H.
Published: July 2021

Because of the nonuniform distribution of earthquake epicenters, a uniform distribution of seismological stations is not necessarily optimal for sampling the Earth in order to determine global Earth structure. Taking into account the already existing digital long-period seismological stations (GDSN, IDA, and GEOSCOPE), we propose a strategy for the siting of additional stations. Here, we shall develop a criterion designed to optimize global resolution of upper mantle structre using mantle wave observations; other kinds of seismological studies will lead to different criteria, which should, however, be amenable to a similar treatment.

For an Earth model developed in spherical harmonics up to a high degree M, and for a given distribution of epicenters and stations, the variance of the solution expanded to some lower degree L ≦ M is obtained at each point of the earth surface by use of averaging kernels, the width of which depends on L. Two measures of the efficiency of an additional station are the reduction of the mean variance and the reduction of the variance oscillations over the Earth's surface; these measures of “new station efficiency” are mapped as a function of the location of the new station (Figures 8 and 9) for the averaging kernels corresponding to L = 8.

Considering the reduction of variance oscillations as the main aim, we find that a new station added in south east Africa, in the eastern Pacific, or in Pakistan is up to 6 times more efficient than a station added randomly, and many times more effective than a station added in the Central United States, the Philippines, or Japan.
Deformation near the epicenter of the 1984 Round Valley, California, earthquake
Authors: Gross W. K. , Savage J. C.
Published: July 2021

A trilateration network extending from near Mammoth Lakes to Bishop, California, was resurveyed following the 23 November 1984, Round Valley earthquake (ML = 5.8). The network had previously been surveyed in 1982. Deformation apparently associated with the Round Valley earthquake was detected as well as deformation due to the expansion of a magma chamber 8 km beneath the resurgent dome in the Long Valley caldera and right-lateral slip on the uppermost 2 km of the 1983 rupture surface in the south moat of the caldera. The deformation associated with Round Valley earthquake suggests left-lateral slip on the north-northeasterly striking vertical plane defined by the aftershock hypocenters located by A. S. Ryall. The earthquake moment implied by the deformation is about 3.8·1017 N-m, a value equivalent to an earthquake magnitude ML = 5.7 in good agreement with the observed magnitude of 5.8. A 0.053 km3 expansion of the magma chamber and 0.32 m slip on the 1983 rupture surface in the 1982-1985 interval was also required to account for the observed deformation.
Estimates of seismic wave attenuation in northern Baja California
Authors: Rebollar Cecilio J. , Traslosheros Carlos , Alvarez Rosa
Published: July 2021

By applying the spectral ratio method and the coda wave theory of Aki and Chouet (1975) to digital records of microearthquakes in Baja California, we have determined the seismic quality factors Qα, Qβ independent of frequency, and Qc(f) and Qβ(f) as a function of frequency. We found that Qα and Qβ, independent of frequency and in the range from 3 to 25 Hz, increase with the difference in epicentral distance between two stations. At short distances (∼ 16 km), Qβ is approximately 65, and at longer distances (∼83 km), Qβ increases to 700. We obtained only three values of Qβ/Qα (1.11, 1.47, and 0.87).

Qc(f) and Qβ(f) were calculated from events recorded around the San Miguel fault at distances not greater than 30 km and source depths between 5 and 15 km. Qc(f) = (37 ± 13)f0.87±0.04 was found in the range of frequencies from 3 to 24 Hz. We found that the minimum mean free path was almost constant (15 km) for the range of frequencies analyzed. Determinations of Qβ(f) were performed using two lapse times. At short lapse time (10 sec), Qβ(f) was almost linear with frequency, increasing from 43 at 3 Hz to 392 at 24 Hz [Qβ(f) = 13f1.03]. These values correspond to near-surface attenuation. On the other hand, at relative long lapse time (16 sec), Qβ(f) increases from 147 at 3 Hz to 625 at 24 Hz [Qβ(f) = 70f0.74]. These last values of Qβ(f) are within the range of variation of Qc(f).
Effects of station coverage on moment tensor inversion
Authors: Satake Kenji
Published: July 2021

The effects of station distribution and focal mechanism on moment tensor inversion are examined by means of numerical experiment. The far-field displacements of P and Rayleigh waves computed from fault models are inverted to the moment tensor after the error corresponding to the observation error is added to the displacement. The rms error is defined as rms of the differences between the given fault parameters and the parameters obtained from the inverted moment tensor. Experiments are made for both ideal and actual station coverages. The rms errors are found to be proportional to the random error added. For the ideal station coverages, the rms errors are smaller for strike-slip type events than for dip-slip types when only P waves are used. Both types give similar errors when only Rayleigh waves are used. For the actual station distribution of the SRO/ASRO network and earthquakes all over the world, the rms errors vary significantly with the location and mechanism of the events. The minor double couple, which must vanish if no errors are added, reaches 30 per cent of the major double couple for some events when the standard deviation of the random error is 10 per cent of the amplitude. These experiments indicate that the station coverage causes serious effects on moment tensor inversion, and we must be careful to interpret the routinely determined results. Furthermore, uniform station distribution of the global seismograph network is desirable.
GeneralP, type-IS, and type-IISwaves in anelastic solids; inhomogeneous wave fields in low-loss solids
Authors: Borcherdt Roger D. , Wennerberg Leif
Published: July 2021

The physical characteristics for general plane-wave radiation fields in an arbitrary linear viscoelastic solid are derived. Expressions for the characteristics of inhomogeneous wave fields, derived in terms of those for homogeneous fields, are utilized to specify the characteristics and a set of reference curves for general P and S wave fields in arbitrary viscoelastic solids as a function of wave inhomogeneity and intrinsic material absorption. The expressions show that an increase in inhomogeneity of the wave fields causes the velocity to decrease, the fractional-energy loss (Q−1) to increase, the deviation of maximum energy flow with respect to phase propagation to increase, and the elliptical particle motions for P and type-I S waves to approach circularity. Q−1 for inhomogeneous type-I S waves is shown to be greater than that for type-II S waves, with the deviation first increasing then decreasing with inhomogeneity. The mean energy densities (kinetic, potential, and total), the mean rate of energy dissipation, the mean energy flux, and Q−1 for inhomogeneous waves are shown to be greater than corresponding characteristics for homogeneous waves, with the deviations increasing as the inhomogeneity is increased for waves of fixed maximum displacement amplitude. For inhomogeneous wave fields in low-loss solids, only the tilt of the particle motion ellipse for P and type-I S waves is independent to first order of the degree of inhomogeneity. Quantitative estimates for the characteristics of inhomogeneous plane body waves in layered low-loss solids are derived and guidelines established for estimating the effect of inhomogeneity on seismic body waves and a Rayleigh-type surface wave in low-loss media.
Surface-wave studies of some South Carolina earthquakes
Authors: Herrmann Robert B.
Published: July 2021

Long-period surface waves generated by three South Carolina earthquakes are used to infer focal mechanisms and seismic moments of the events. The 3 February 1972 Bowman, South Carolina, earthquake is found to be shallow and to require an almost strike-slip focal mechanism with pressure axes trending northeast-southwest. The 22 November 1974 Charleston, South Carolina, earthquake was smaller and was recorded by only three long-period WWSSN stations. For this earthquake, only an estimate of the seismic moment and focal depth were possible. The focal mechanism of the 2 August 1974 Clarkhill reservoir earthquake indicated motion on a northwest striking almost vertical dip-slip fault. In order to specify preferred motions on the nodal planes, full waveform modeling of the long-period traces at ATL was necessary. The results are not without ambiguity, but represent the best estimates of source parameters for these earthquakes.
Studies of crustal converted waves using short-period seismograms recorded in the Vanuatu Island arc
Authors: Chiu Jer-Ming , Isacks Bryan L. , Cardwell Richard K.
Published: July 2021

On three-component, short-period, digital array recordings, S to P converted phases from three major crustal discontinuities beneath Efate Island are identified between the primary P and S arrivals. The time differences between the main S arrival and these converted phases (Sp1, Sp2, and Sp3) provide constraints on the crustal structure beneath Efate Island. A crustal model with three layers over a half-space is determined, which is consistent with the results of a published refraction experiment in the southern Vanuatu (formerly New Hebrides) island arc.
Modeling source zone boundary uncertainty in seismic hazard analysis
Authors: Bender Bernice
Published: July 2021

Most probabilistic seismic hazard studies assume that future earthquakes will occur in clearly defined, seismically homogeneous areal source zones. This assumption means that modeled seismic rates change abruptly at source zone boundaries, with the result that predicted acceleration levels may differ considerably at sites a few kilometers apart near a boundary (e.g., changes of 50 to 80 per cent or more at sites 20 km apart). However, homogeneous source zones are at best an approximation, and the areal extent of such zones is usually not well determined. I propose modifying the model so that the seismicity originally associated with each point in a source zone instead be regarded as normally distributed with standard deviation σ about that point; this permits seismicity to vary smoothly across source zone boundaries. When this variability is modeled, if σ is 25 per cent or less of the width of the source zone, acceleration levels calculated at sites at the center of the zone and at sites on the boundary are about the same as those calculated when no location variability (σ = 0) is assumed; however, calculated levels decrease at sites between the center and the boundary, and increase at sites outside the boundary. The changes tend to become larger at the higher accelerations corresponding to longer exposure times.

When earthquakes are modeled as ruptures along well-defined linear faults, predicted accelerations also increase significantly as the site location approaches the fault. However, in many cases, neither the location of a fault nor the definitions of its end points can be precisely stated. Acceleration as a function of site location will vary more smoothly if possible fault locations are regarded as either normally or uniformly distributed.
Rupture patterns and preshocks of large earthquakes in the southern San Jacinto fault zone
Authors: Sanders Chris , Magistrale Harold , Kanamori Hiroo
Published: July 2021

We relocated the large 1937, 1942, and 1954 earthquakes in the San Jacinto fault zone. The epicenters of the main shocks, aftershocks, and some preshocks were determined using empirical station corrections from recent small events in the study areas. The 1937 (ML 5.9) earthquake has an epicenter between the surface traces of the San Jacinto and Buck Ridge faults, and aftershocks suggest about 7 km of rupture predominantly to the northwest. A significant increase in small earthquake activity occurred about 112 yr before this event. The 1954 (ML 6.2) earthquake is located at the southeast end of the mapped trace of the San Jacinto fault, and aftershocks suggest about 15 km of rupture further southeast into an area of folded young sediments with no surface fault trace. This event was preceded by a cluster of small earthquakes which occurred within an 8-hr period 10 weeks before the main event and in the eventual rupture zone. The 1942 (ML 6.3) earthquake is located southwest of the southeast end of the Coyote Creek fault. Large aftershocks of this event are spread over a 15 by 18 km area southwest of the Coyote Creek fault and are not associated with any one fault. The relation of the 1942 event to the San Jacinto fault zone is not simple.
Moment magnitude scale for local earthquakes in the Petatlan region, Mexico, based on recorded peak horizontal velocity
Authors: Mahdyiar M. , Singh S. K. , Meyer R. P.
Published: July 2021

Assigning moment magnitude to local earthquakes based on peak recorded amplitude and hypocentral distance is the principal concern of this paper. For 38 aftershocks of the Petatlan earthquake (14 March 1979) with moments between 2.8 × 1018 and 1.4 × 1022 dyne-cm, we developed an empirical relationship for the estimation of moment based on peak horizontal velocity (V) and hypocentral distance (R). This empirical relationship in conjunction with the definition of moment magnitude (Hanks and Kanamori, 1979) allows direct estimation of moment magnitude, knowing peak horizontal velocity and hypocentral distance. We call this estimation of moment magnitude “Mw′” to distinguish it from its original definition. Equation for Mw′ for our data set is

M w ' = 2 . 2 7 + 0 . 7 7 log ( V ⋅ R ) + 6 . 5 9 × 1 0 - 3 R ,

where V is in millimeters/second, and R is in kilometers.

In order to be able to estimate the moment magnitude from coda duration (Tc), we sought and found correlation between log(Tc) and log of moment (M0) as follows

log M 0 = ( 2 . 2 5 ± 0 . 1 7 ) log ⁡ T c + ( 15.88 ± 0.29 ) ,

where M0 is in dyne-cm, and Tc is in seconds.
Phase speed perturbations and three-dimensional scattering effects of surface waves due to topography
Authors: Snieder Roel
Published: July 2021

Linearized scattering theory is used to describe three-dimensional surface wave scattering by topography on a layered medium. A short derivation for the scattered surface wave is presented. The implications and limitations of the scattering theory are discussed qualitatively. Furthermore, an expression is presented for the partial derivatives of the surface wave phase velocities with respect to topography. It is shown that for periods between 15 and 30 sec, the fundamental mode phase velocity perturbation due to topography is of the order of 1 per cent for a mountain of 1 km height. For the higher mode phase velocities, the effects of topography are negligible.
Estimation of earthquake source parameters by the inversion of waveform data: Global seismicity, 1981-1983
Authors: Spikin Stuart A.
Published: July 2021

A waveform inversion algorithm, based on optimal filter theory, has been applied to the P waves from 260 of the largest earthquakes occurring during the years 1981 through 1983. Estimates of average focal depth, scalar moment, and deviatoric source mechanism have been obtained. For all except the largest events (M0 > 1027 dyne-cm), the scalar moments obtained in this study are close to, but somewhat larger than, the Harvard centroid-moment tensor (CMT) scalar moments. The CMT estimates of scalar moment are probably biased to low values due to the way unmodeled lateral heterogeneity affects the fitting procedure. For the largest events, however, source complexity can bias the scalar moments determined in this study to lower values, and the CMT scalar moments are probably more accurate. The moment tensor, CMT, and U.S. Geological Survey first-motion source mechanisms have been objectively compared by computing the locations of the vector representations of the mechanisms on the unit sphere. We find that the similarities and differences between these mechanisms can be related to the uncertainties inherent in each method for certain types of earthquakes: (1) lack of constraint on one of the nodal planes for dip-slip type mechanisms from first-motion analysis; (2) lack of resolution of the moment tensor elements defining the dip-slip component of faulting for shallow-focus earthquakes in the CMT method; and (3) lack of resolution of the moment tensor elements defining the strike-slip component of faulting in the P-wave inversion method used here. Thus, on the average, the first-motion and CMT methods yield the more reliable mechanisms for strike-slip-type earthquakes, and the method used in this study gives a more reliable result for shallow-focus earthquakes with dip-slip-type mechanisms. Finally, both of the moment tensor methods should yield reliable solutions for intermediate- and deep-focus earthquakes.
Interplate coupling and temporal variation of mechanisms of intermediate-depth earthquakes in Chile
Authors: Astiz Luciana , Kanamori Hiroo
Published: July 2021

We investigated the temporal variation of the mechanism of large intraplate earthquakes at intermediate depths in relation to the occurrence of large under-thrusting earthquakes in Chile. Focal mechanisms were determined for three large events (1 March 1934: M = 7.1, d = 120 km; 20 April 1949: M = 7.3, d = 70 km; and 8 May 1971: MW = 7.2, d = 150 km) which occurred down-dip of the great 1960 Chilean earthquake (MW = 9.5) rupture zone. The 1971 event is down-dip compressional: θ (strike) = 12°, δ (dip) = 80°, and λ (rake) = 100°. The 1949 earthquake focal mechanisms is θ = 350°, δ = 70°, and λ = −130°. The data available for the 1934 event are consistent with a down-dip tensional mechanism. Thus, the two events which occurred prior to the great 1960 Chilean earthquake are down-dip tensional. Published fault plane solutions of large intermediate-depth earthquakes (28 March 1965 and 7 November 1981) which occurred down-dip of the Valparaiso earthquakes of 1971 (MW = 7.8) and 1985 (MW = 8.0) are also down-dip tensional. These results suggest that before a major thrust earthquake, the interplate boundary is strongly coupled, and the subducted slab is under tension at intermediate depths; after the occurrence of an interplate thrust event, the displacement on the thrust boundary induces transient compressional stress at intermediate depth in the down-going slab. This interpretation is consistent with the hypothesis that temporal variations of focal mechanisms of outer-rise events are due to changes of interplate coupling.
Phase analysis of Rayleigh waves from the Shagan River test site in the USSR
Authors: Herrin Eugene , Goforth Tom
Published: July 2021

A study was made to determine if significant phase differences exist between Rayleigh waves which have traveled almost identical paths from the USSR Shagan River test site. Surface waves from five explosions recorded at six SRO/ASRO digital stations were used in the analysis. The explosion of 4 August 1979 was selected as a reference, and at each site the phase spectra of the Rayleigh waves from the other five events were compared to that of the reference. The technique of phase-matched filtering was used to analyze the signals. This technique reduces the effects of multipathing and removes phase differences due to dispersion along slightly different travel paths.

Each epicenter had been relocated by using calibration data from the cratering shot of 15 January 1965, and remaining errors in location and origin time are considered to be extremely small. Seismograms were analyzed for surface waves recorded at: Matsushiro, Japan (MAJO); Shillong, India (SHIO); Kabul, Afghanistan (KAAO); Ankara, Turkey (ANTO); Grafenburg, West Germany (GRFO); and Albuquerque, New Mexico (ANMO).

Results of the study indicate that Rayleigh waves from some Shagan River explosions have undergone large phase shifts relative to Rayleigh waves which have traveled almost identical paths from other Shagan River explosions. In some cases, the phase shifts can be interpreted as complete phase reversals with associated time delay. In particular, as compared to the explosion of 4 August 1979, Rayleigh waves from the explosion of 7 July 1979 are reversed in polarity at KAAO and ANTO and are reversed in polarity and delayed at GRFO, SHIO, and MAJO.
Apparent stresses, stress drops, and amplitude ratios of earthquakes preceding and following the 1975 HawaiiMS= 7.2 main shock
Authors: Zuñiga F. R. , Wyss M. , Wilson M. E.
Published: July 2021

S-wave spectra for approximately 300 earthquake signals (2.8 ≦ ML ≦ 3.9) were obtained from hand-digitized Wood-Anderson records from Hilo, Hawaii. All sources were located within part of the rupture volume of the 1975 Hawaii MS = 7.2 earthquake. The epicentral distance to Hilo was about 45 ± 3 km, the backazimuth was 180° ± 10° (south), and the sources were located at depths of 9 ± 1.4 km. The apparent stress and Brune stress drop, based on 3-sec windows of the S waves, were examined for possible temporal and spatial dependence. Most of the data showed a remarkable constancy of the average apparent stress and stress drop per event as a function of time. No measurable change in average signal content took place at the time of the main shock. A statistically significant difference in the average stress parameters per event was found between neighboring subvolumes (radius ≈ 5 km) of the 1975 aftershock zone: a volume previously proposed as asperity based on seismicity pattern interpretation contained earthquakes with higher apparent stresses of ησ=9.0±8.8 bars compared to the neighboring volume with ησ = 4.2 ± 6.1 bars. Seventy-eight spectra obtained from a second station showed the same difference between the two volumes as that found at station Hilo, suggesting that the signal differences should be interpreted in terms of source differences. In addition, amplitude ratios of SV/P waves measured at Hilo showed that a systematic difference of 10° in fault plane orientation existed during years before the 1975 main shock. This agrees with the rotation of the fault plane during the main rupture reported elsewhere. We hypothesize that heterogeneities along the fault plane with dimensions of about 5 km cause changes in fault plane dip, differences in average stress release per earthquake, strong contrasts in seismicity patterns, and differences in aseismic strain release by fault creep. These same heterogeneities in the fault plane apparently also control the location of major earthquakes and the complexity of their ruptures.
A fast algorithm for two-point seismic ray tracing
Authors: Um Junho , Thurber Clifford
Published: July 2021

A new approximate algorithm for two-point ray tracing is proposed and tested in a variety of laterally heterogeneous velocity models. An initial path estimate is perturbed using a geometric interpretation of the ray equations, and the travel time along the path is minimized in a piecewise fashion. This perturbation is iteratively performed until the travel time converges within a specified limit. Test results show that this algorithm successfully finds the correct travel time within typical observational error much faster than existing three-dimensional ray tracing programs. The method finds an accurate ray path in a fully three-dimensional form even where lateral variations in velocity are severe. Because our algorithm utilizes direct minimization of the travel time instead of solving the ray equations, a simple linear interpolation scheme can be employed to compute velocity as a function of position, providing an added computational advantage.
Source parameter analysis from strong motion records of the Friuli, Italy, earthquake sequence (1976-1977)
Authors: De Natale Giuseppe , Madariaga Raul , Scarpa Roberto , Zollo Aldo
Published: July 2021

Time and frequency domain analyses are applied to strong motion data recorded in Friuli, Italy, during 1976 to 1977. An inversion procedure to estimate spectral parameters (low frequency level, corner frequency, and high frequency decay) has been applied to displacement spectra using a simple earthquake source model with a single corner frequency.

The data were digitized accelerograms from ENEA-ENEL portable and permanent networks. Instrument-corrected SH waves were selected from a set of 138 three-component, hand-digitized records and 28 automatically digitized records. Thirty-eight events with stations having 8 to 32 km epicentral distance were studied.

Different stress drop estimates were performed showing high values (200 to 300 bars, on the average) with seismic moments ranging from 2.8 × 1022 to 8.0 × 1024 dyne-cm.

The observation of systematic higher values of Brune stress drop (obtained from corner frequencies) with respect to other time and frequency domain estimates of stress release, and the evidence on time series of multiple rupture episodes suggest that the observed corner frequencies are most probably related to subevent ruptures rather than the overall fault size.

Seven events recorded at more than one station show a good correlation between rms, Brune, and dynamic stress drops, and a constant scaling of this parameter as a function of the seismic moment. When single station events are also considered, a slight moment dependence of these three stress drop estimates is observed differently. This may be explained by an inadequacy of the ω−2 high-frequency decay of the source model or by high-frequency attenuation due to propagation effects.

The high-frequency cutoff of acceleration spectra indicates the presence of an Fmax in the range of 5 to 14 Hz, except for the stations where local site effects produce spectral peaks.
Source characteristics of earthquakes in the Michoacan seismic gap in Mexico
Authors: Astiz Luciana , Kanamori Hiroo , Eissler Holly
Published: July 2021

We investigated the source characteristics of large earthquakes which occurred in the Michoacan, Mexico, seismic gap during the period from 1981 to 1986 in relation to historical seismicity in the region. The rupture pattern of the Michoacan gap during this period can be characterized by a sequential failure of five distinct asperities. Before 1981, the Michoacan gap had not experienced a large earthquake since 1911 when an MS = 7.8 earthquake occurred. The recent sequence started in October 1981 with the Playa Azul earthquake which broke the central part of the gap. Body-wave modeling indicates that the Playa Azul earthquake is 27 km deep with a seismic moment of 7.2 × 1027 dyne-cm. It is slightly deeper than the recent Michoacan earthquakes, and its stress drop is higher, suggesting a higher stress level at depths in the Michoacan gap. The seismic moment of the 19 September 1985 (Mw = 8.1) earthquake was released in two distinct events, with the rupture starting in the northern portion of the seismic gap and propagating to the southeast with low moment release through the area already broken by the 1981 Playa Azul earthquake. The rupture propagated further southeast with an Mw = 7.5 event on 21 September 1985. Another aftershock occurred on 30 April 1986 to the northwest of the 19 September main shock. Body-wave modeling indicates that this event has a simple source 10 sec long at 21 km depth, and fault parameters consistent with subduction of the Cocos plate (ϑ = 280°, δ = 12°, and λ = 70°) and M0 = 2.0 to 3.1 × 1026 dyne-cm (Mw = 6.8 to 6.9). Although this distribution of asperities is considered characteristic of the Michoacan gap, whether the temporal sequence exhibited by the 1981 to 1986 sequence is also characteristic of this gap or not is unclear. It is probable that, depending on the state of stress in each asperity, the entire gap may fail in either a single large event with a complex time history or a sequence of moderate to large events spread over a few years. The seismic moment and the time since the last earthquake in Michoacan (in 1911) fit an empirical relation between moment and recurrence time found for the Guerrero-Oaxaca region of the Mexico subduction zone.
Seismic imaging of the site response using microearthquake recordings. Part I. Method
Authors: Scherbaum Frank
Published: July 2021

Microearthquake signals from widely distributed geographical regions have been noticed repeatedly to be strongly affected by local site effects. The corresponding seismograms contain important information on the individual propagation path. A single station inversion method is presented which allows the imaging of the subsurface impedance structure from locally recorded SH waves records.

The technique is based on the Kunetz-Claerbout equation which in its original form states the relationship between the transmission response and the reflection response for P waves in a horizontally layered medium and vertical incidence (Claerbout 1968). By adapting Claerbout's formulation to the transmission problem for SH waves under oblique incidence, microearthquake recordings can be used to calculate corresponding pseudo-reflection seismograms which in turn can be inverted for the impedance structure by exploiting Levinson recursion.

Limitations in the high-frequency content of the signals due to the combined effects of absorption, recording system, and bandlimited source signals, as well as the influence of noise, drastically reduce the resolutional power of the inversion procedure. A number of different deconvolution techniques have been tested with synthetic seismograms for the applicability to reduce these effects. Good results have been obtained with the blind deconvolution technique of Scherbaum and Stoll (1985), utilizing the minimum phase property of the Green's function.

From the analysis of synthetic data, it can be expected that for realistic source-receiver situations and short-period recording systems, the main reflectors down to a depth of several hundreds of meters could be resolved.
Seismic imaging of the site response using microearthquake recordings. Part II. Application to the Swabian Jura, southwest Germany, Seismic network
Authors: Scherbaum Frank
Published: July 2021

The subsurface site structure of the Swabian Jura, southwest Germany, seismic network has been modeled from the inversion of locally recorded SH wave microearthquake seismograms. The observed records have been deconvolved from the effects of apparent source pulse broadening due to the combined influence of frequency bandlimited source signals, absorption, peg leg multiple reflections, and the recording system following the procedure of Scherbaum and Stoll (1985). Corresponding pseudo-reflection seismograms were calculated based on the Kunetz-Claerbout relation for SH waves and inverted using a Levison recursion algorithm. The final structural models have been optimized in terms of numbers of layers and depth resolution using Ferber's (1985) noise stabilization technique.

The resulting impedance models for the Swabian Jura, southwest Germany, seismic network show some strongly correlated reflectors in the uppermost layers, which are well understood in terms of the local stratigraphy. The comparison of the inverted impedance model HSN with the P-wave velocity log from a nearby exploration drilling (Trochtelfingen, BEB) shows a high degree of similarity of the dominating reflectors down to a depth of several hundred meters.

As a consequence, the coda-generating process for the early part of the coda of the observed Swabian Jura microearthquake seismograms (Wood-Anderson magnitude MWA < 3.0) can be completely interpreted as an effect of the local subsurface structure.
The Determinants of Inflation in Emerging Markets and Developing Countries: A Literature Review
Authors: ASFUROĞLU Dila
Published: July 2021

A vast literature exists on the determinants of inflation in developed countries whereas the one in emerging markets and developing countries has gained attention at the beginning of 1990s. In this respect, the current paper overviews the empirical studies in order to provide underlying knowledge and common facts on this topic that are valuable for further research and policymakers. The patterns emerge from the results of the existing literature can be summarized as follows. First, inflation is mainly a monetary phenomenon either due to direct or indirect drivers in these countries. However, the significance of the effects from the monetary aggregates are dependent on the countries and periods under study. Secondly, inflation persistence is a major determinant in explaining inflation, suggesting a backward-looking behavior in inflation dynamics for these countries. Lastly, the importance of domestic determinants in understanding inflation has shifted towards external ones implying a greater role for global determinants in the last two decades.
Target adjustment model and new working capital management performance measure: Evidence from Croatia
Authors: Korent Dina
Published: July 2021

The paper develops a dynamic panel model of target adjustment in order to investigate the determinants of the cash conversion cycle of companies in manufacturing, trade, and information and communication industries in the Republic of Croatia for the period 2008-2015. The emphasis is on examining the significances and the speeds of the adjustment processes of the cash conversion cycles of companies subsamples by industry and size. Due to the adjustment costs, the results show that the observed companies gradually adjust their current cash conversion cycles to the target ones. In addition, these adjustments were slow, which can be explained by the predominance of the adjustment costs over the costs of being in disequilibrium. Moreover, the results of this study indicate that the rate of adjustment varies among companies from different industries and size categories. The differences in market power allow companies to change more easily the components of the cash conversion cycle. As a result, they enable faster convergence to their target levels. Besides the lagged cash conversion cycle, tested potential determinants that significantly affect the cash conversion cycles of Croatian companies in selected industries, although with different robustness, are company size, company growth, return on assets, fixed asset investments, financial leverage and the growth of the real gross domestic product. Finally, the paper presents a new measure for working capital management performance.
Policy orientation, knowledge dynamic ability and green innovation: A mediation model based on China provincial panel data
Authors: Fang Li , Sheng Zhang
Published: July 2021

Environmental supervision and government subsidy are important tools for government to promote green innovation. The influence of these two policy orientations on green innovation performance is spreading widely, but the specific indirect mechanism of policy orientation inducing green innovation needs further exploring. This paper introduces the knowledge-dynamic ability (knowledge production ability, knowledge acquisition ability, knowledge integration ability) into the analysis framework of enterprise green innovation, and studies the mediating effect of the knowledge-dynamic ability on policy orientation and green innovation. Based on the panel data of 30 provinces in China from 2000 to 2015, the empirical findings are as follows: Firstly, the knowledge-dynamic ability plays a remarkable mediating role in promoting between policy orientation and green innovation, which indicates that improving the knowledge-dynamic ability is a core mechanism of policy orientation to induce enterprise green innovation. Secondly, the knowledge-dynamic ability plays a complete mediating role in the relationship between environmental supervision and green innovation. Environmental supervision promotes green process innovation by enhancing knowledge acquisition ability and induces green product innovation by enhancing knowledge production ability. Thirdly, the knowledge-dynamic ability plays a partial mediating role in the relationship between government subsidy and green innovation. Government subsidy improves enterprise green process innovation by enhancing knowledge acquisition ability and knowledge integration ability, and induces enterprise green product innovation by enhancing knowledge production ability and knowledge integration ability.
The Analysis of Influence of BIM Technology on the Performance of China Construction Production Operation and Maintenance System from the Perspective of System Theory and Information Theory
Authors:   the Tianjin University, China, Zhang Xiaomeng
Published: July 2021

In China, the construction industry is divided into the secondary industry, with the division of "construction industry", and the definition of "architecture". However, for construction production, operation and maintenance, we generally use stages to carry out restricted. After analyzing the concepts of industry, field, and construction, the author regards construction production operation and maintenance as a system, and analyzes project establishment, design, construction, and operation and maintenance as the four elements of the system. Analyze the impact of BIM technology on the performance of the system from the perspective of system theory and information theory, and demonstrate that the application of BIM technology will bring about the optimization of the performance of the building production operation and maintenance system, which is the best way for the construction industry to achieve industrial upgrading. The focus of the development of BIM technology application should be on the reconstruction of the system structure and the cooperation mode of all parties, that is, the production relationship. In the end, the author looks forward to the future development of BIM technology.
Does Financing Structure Relates to Liquidity Risk? A Comparative Study of Islamic and Conventional Banks of Pakistan
Authors: Qadri Hussain Mohi-ud-Din , Mustafa Atta UI , Ali Hassnian
Published: July 2021

The purpose of this paper is to find out whether financing in specific sectors increase bank liquidity risk and how this goes on with both Islamic and conventional banks. The paper used pooled regression, fixed effect model and random effect model decided on the basis of dummy joint significant test. The result shows that only financing concentration (SPEC) proved to have significant association with Islamic and overall banking sector for short run. And all other banks specific variables are unable to show a significant result. While the macroeconomic variable GDP and Inflation have a strong relationship in both long run and short run time period. This paper add value to the existing literature on liquidity risk under the new indicators issued by Basel III.
Trusting Online Reviews Enhances Intention to Book Online: The Perks of Seeking Information?
Authors: Zahidah Shafira Rahma , Rostiani Rokhima
Published: July 2021

Research aims: This study aims to analyze factors affecting consumer intention to book hotels from social media and online travel agencies. Specifically, we examine the direct effects of social media usage and electronic word of mouth (e-WoM) and the indirect effect through the mediation of trust in booking intention.Design/Methodology/Approach: Purposively sampled respondents resulted in 409 responses that met the predefined criteria: aged 18-34, active on their social media accounts, and had accessed online booking sites. Regression with mediating analysis was conducted on valid data.Research findings: Analysis results showed that social media usage and e-WoM had a direct, positive, and significant impact on booking intention. It has also proven to have an indirect effect on consumer booking intention mediated by trust. Social media usage and e-WoM directly affected booking intention and had higher valence when mediated by trust.Theoretical contribution/Originality: Information on social media positively influenced consumer purchase intention on online hotel booking due to its completeness. Further, this study is among the few that applied the e-WOM concept to the hospitality sector.Practitioner/Policy implication: The implication for managers is to improve the online booking management system by increasing promptness in response to reviews, especially the negatives.Research limitation/Implication: This study focused on consumers who have social media accounts and accessed online hotel booking sites, limiting its generalizability.
Апробація каталізаторів палива на авіаційних двигунах
Authors: Kozlov Volodymyr , Volianska Larysa , Omelianenko Serhiy , Yakushenko Оleksander , Flokos Mark
Published: July 2021

Проведено дослідження впливу каталізаторів палива української фірми «Авто-Эко-Титан», що пройшли перед тим випробування на поршневих двигунах внутрішнього згорання різного виду транспорту (автомобільного, залізничного, морського) та показали суттєве покращення техніко-економічних та екологічних показників. Можливість використання даних каталізаторів у газотурбінній авіації досліджувалась на авіаційних газотурбінних двигунах.
Интерактивная технология как развивающий элемент обучения иностранному языку в вузе
Authors: Серебрянцева О.Г.
Published: July 2021

Метод case-study или метод кейсов, который можно назвать развивающим методом и интерактивной кейс-технологией, становится все более актуальным в российской образовательной системе и начинает активно применяться преподавателями иностранного языка в нелингвистических вузах, что позволяет формировать и развивать профессиональные коммуникативные навыки. Интерактивная кейс-технология вовлекает студентов в активную классную, групповую и самостоятельную работу, позволяет формировать знания, умения и навыки на основе анализа и решения реальной или смоделированной проблемной ситуации, представленной в виде случая.
Новый взгляд на эмоциональное состояние, психику, психологию и физиологию ощущений. Техника «Паруса»
Authors: Шанин А.В.
Published: July 2021

В данной статье описывается авторская техника дыхания «Паруса», которая позволяет добиться изменения эмоционального состояния «непосредственно», без помощи внешних стимулов. Приведен краткий экскурс по этапам открытия данной методологии самим автором, а также по ее тестированию и практическому применению.
The mediation model of the effect of intelligence on the personal well-being of people with dementia
Authors: Suvorova I.Yu. , Efremova D.N. , Glebov V.V.
Published: July 2021

The article is devoted to the study of factors influencing the level of psychological well-being of elderly people with dementia. As a result of statistical calculations, a model was built that proves the indirect influence of intellectual development on subjective well-being. Mediating factors are the ability to interact with others, the emotional regulation, existential fulfillment and the analysis of inner states.