bluuebunny/crossref_metadata_2025_split huggingface dataset:
The propagation of Love waves across nonhorizontally layered structures
Authors: Lysmer John , Drake Lawrence A. 
Published: September 2021

abstract
A finite element technique is developed to study the propagation of Love waves across nonhorizontally-layered structures. A half-space is approximated by a rigid base at great depth. Previous results of other authors are confirmed. Detailed models of a continental boundary and of a structure including a slab of lithosphere dipping downard at an angle of 45° are analyzed. For incident fundamental Love-mode motion, at a period of 25 sec, on either side of the model of a continental boundary, the total energy in all of the reflected modes is found to be less than 0.1 percent of the incident energy, while the energy in the transmitted higher modes is 48 percent of the incident energy. These results are strikingly different from the results for previous models of a continental boundary. For incident fundamental Love-mode motion, at a period of 25 sec, on the “oceanic” side of the model including the dipping slab, the total energy in the reflected modes is found to be approximately 1 percent of the incident energy, and that in the transmitted higher modes, 36 per cent of the incident energy. For incident fundamental Love-mode motion, at a period of 25 sec, on the “shallow sea” side of the model including the dipping slab, the total energy in the reflected modes is found to be approximately 3 percent of the incident energy, and that in the transmitted higher modes, 34 percent of the incident energy.
On the computation of seismic ray travel times and amplitudes
Authors: Chapman C. H. 
Published: September 2021

abstract
The usual methods of interpolating velocity-depth profiles cause discontinuities in the velocity gradient and anomalous geometrical ray amplitudes. Numerical methods are presented for interpolating a velocity profile and evaluating the ray integrals which avoid these difficulties. They allow smooth amplitude curves to be calculated directly. An example is given for the Herrin P velocity profile.
Reflections from discontinuities beneath antarctica
Authors: Adams R. D. 
Published: September 2021

abstract
Early reflections of the phase P′P′ recorded at North American seismograph stations from nuclear explosions in Novaya Zemlya are used to examine the crust and upper mantle beneath a region of eastern Antarctica. Many reflections are observed from depths less than 120 km, indicating considerable inhomogeneity at these depths in the Earth. No regular horizons were found throughout the area, but some correlation was observed among reflections at closely-spaced stations, and, at many stations, reflections were observed from depths of between 60 and 80 km, corresponding to a likely upper boundary of the low-velocity channel. Deeper reflections were found at depths of near 420 and 650 km. The latter boundary was particularly well-observed and appears to be sharply defined at a depth that is constant to within a few kilometers. The boundary at 420 km is not so well defined by reflections of P′P′, but reflects well longer-period PP waves, arriving at wider angles of incidence. This boundary appears to be at least as pronounced, but not so sharp as that near 650 km. The deep structure beneath Antarctica presents no obvious difference from that beneath other continental areas.
Deformation of a multilayered half-space by stress dislocations and concentrated forces
Authors: Singh Sarva Jit 
Published: September 2021

abstract
The problem of the static and dynamic response of a nonhomogeneous, isotropic, elastic half-space to stress dislocations and concentrated forces is discussed. Integral expressions for the displacements are obtained in the case of a two-layered half-space. Results of Singh (1970) are used to study the static deformation of a multilayered half-space caused by a point source placed at an arbitrary depth below the free surface. The source is represented as a discontinuity in the z-dependent coefficients of the displacement and stress integrands at the source level.
A note on the effect of simple topography on seismicSHwaves
Authors: Boore David M. 
Published: September 2021

AbstractFinite difference calculations for SH-motion, as well as field observations, show that topography can have significant effects on seismic waves when the incident wavelengths are comparable to the size of the topographic features and the topographic slopes are relatively steep. These effects are frequency-dependent and can range from amplification to deamplification at a given site. For the models considered in this paper, amplifications of 75 per cent as compared to motions produced in regions of no topography were found. A qualitative discussion of the strong-motion accelerogram recorded at Pacoima Dam from the San Fernando earthquake of February 9, 1971, suggests that the recorded accelerations could, at any period, be expected to differ by 25 to 50 per cent from those that would have been recorded if no topographic features were present. The complex terrain precludes a prediction of the actual magnitude or sign of the difference. The present results are probably most significant from the viewpoint of engineering seismology, for the conditions required for a significant topographic effect are most likely to occur in the period range of engineering interest.
Disturbances in semi-infinite heterogeneous media generated by torsional sources. I
Authors: Sidhu R. S. 
Published: September 2021

abstract
This paper studies the generation of axially symmetric transient SH waves in semi-infinite heterogeneous media in which μ and ρ vary with depth. The sources generating these waves are taken in the form of time-dependent torsional-body forces of finite dimensions. The solution is obtained using Hankel and Laplace transforms and Green's function. The disturbance from a buried point source of impulsive type is discussed in two cases, (a) μ = μo(1 + ɛz)2, ρ = ρo (1 + ɛz)2, (b) μ = μoe2az, ρ = ρoe2az. It is shown that, in contrast to the results for a homogeneous medium, in case (i), the wave reflected by the free surface generates secondary disturbances which trail behind the wave front and die out as t increases; the incident wave in this medium generates no such disturbance. In case (ii), however, both the incident as well as the reflected waves generate secondary disturbances.
Formal solution for the disturbance in a heterogeneous layer of finite depth with stress-free boundaries is discussed in Appendix II.
The use of body-wave spectra in the determination of seismic-source parameters
Authors: Hanks Thomas C. , Wyss Max 
Published: September 2021

abstractTeleseismic determinations of body-wave (P, S) spectra, interpreted in terms of the Brune (1970) seismic-source model, are used to estimate the parameters seismic moment (Mto) and source dimension (r) for three large, shallow, strike-slip earthquakes occurring on nearly vertical fault planes and for which the same parameters can be determined from field (F) data. These earthquakes are (1) the Borrego Mountain, California, earthquake (April 9, 1968) for which [Mo(P) = 10, Mo(S) = 6.6, and Mo(F) = 3.6] × 1025 dyne-cm and [r(p) = 14, r(S) = 23, and L/2(F) = 17] km; (2) the Mudurnu Valley, Turkey, earthquake (July 22, 1967) for which [-Mo(P) = 9.1, Mo(S) = 8.5, and Mo(F) = 7.4] × 1026 dyne-cm, and [r(P) = 39, r(S) = 48, and L/2(F) = 40] km; and (3) the Dasht-e-Bayāz, Iran, earthquake (August 31, 1968) for which [Mo(P) = 4.8, Mo(S) = 8.6, and Mo(F) = 18] × 1026 dyne-cm, and [r(P) = S1, r(S) = 48, and L/2(F) = 40] km. The Brune (1970) model is well-calibrated with respect to the determination of these parameters for the earthquakes considered. A minimum estimate for the radiated energy can be expressed in terms of Mo and r; this estimate is low by a factor of 10 with respect to the estimate obtained from energy-magnitude relations for these three earthquakes. The stress drops of these events are of the order of 10 bars.
Aftershock sequence and focal parameters of the February 28, 1969 earthquake of the Azores-Gibraltar fracture zone
Authors: López Arroyo A. , Udías A. 
Published: September 2021

Abstract
The earthquake of February 28, 1969, which occurred about 500 km west of the Strait of Gibraltar, was felt over the entire Iberian Peninsula, in a wide region of Morocco, and south to the Canary Islands. It had a long sequence of aftershocks continuing for at least 10 months, but, nevertheless, most of the energy seems to have been liberated in the main shock of which the mb was 7.4.
The source mechanism solution indicates a fault plane striking N 67°W and dipping 68°SW, with motion principally of the strike-slip type. There also is some overthrusting. The horizontal extent of faulting is of the order of 90 km.
Application of prediction analysis to hypocenter determination using a local array
Authors: Peters David C. , Crosson Robert S. 
Published: September 2021

Abstract
Prediction analysis provides an efficient means of estimating errors in local earthquake hypocenter determinations using a dense array of seismometers. The standard errors of the hypocentral coordinates and the origin time due to random errors in the data and model parameters may be calculated rigorously for a least-squares hypocenter inversion procedure using arbitrary earth models. Contour maps of the estimated standard errors in the hypocenter parameters are plotted for two array configurations and for several earth models and event depths. These maps are useful in predicting the relative accuracy and difficulty of hypocenter location as a function of position in the array, and in selecting events with small relative error to be used in velocity-structure refinement in the vicinity of the array. In particular, the method may be used to provide a means of optimizing array geometry to provide maximum hypocenter control in specific target regions. Tests were made using hypothetical data with prescribed error distributions showing good agreement with the error analysis.
Quantitative seismicity maps of India
Authors: Kaila K. L. , Gaur V. K. , Narain Hari 
Published: September 2021

AbstractUsing the Kaila and Narain (1971) method, three quantitative seismicity maps have been prepared for the Indian subcontinent which are compared with regional tectonics. These are the A-value map, the b-value map and the return-period map for earthquakes with magnitude 6 and above where A and b are the constants in the cumulative regression curve represented by log N = A - bM. The A-value seismicity map shows that India can be divided into two broad seismic zones, the northern seismically highly active zone and the southern moderately active zone. In the northern active zone, a number of seismic highs have been delineated such as the Pamir high, the northwest-southeast trending Srinagar-Almora high, the Shillong massif high, the Arakan Yoma high and the West Pakistan highs. These seismic highs are consistent with the Himalayan tectonic trends. Contrary to this, two seismic highs fall in the Tibet plateau region which align transversely to the main Himalayan trend. In the southern moderately active zone, two seismic highs are clearly discernible, the east and the west coast high, the latter being seismically more active than the former. The least active zone encompasses the Vindhyan syncline and the areas of Delhi and Aravalli folding. Between this zone and the east coast high lies another moderately active zone which encloses the Godavari graben, western part of the Mahanadi graben and the Chattisgarh depression. The b-value seismicity map also demarcates the same active zones as are brought out on the A-value map. The return-period map of India for earthquakes with magnitude 6 and above shows a minimum return period of 100 years in the Pamirs, about 130 years in the various seismic highs in the northern active zone, 180 years on the west coast high, 200 years on the east coast high and about 230 years in the least active Vindhyan-Aravalli zone and the Hyderabad-Kurnool area. These quantitative seismicity maps are also compared with the seismic zoning map of Indian Standards Institution and seismicity maps of India prepared by other workers.
Elastic velocity anisotropy in the presence of an anisotropic initial stress
Authors: Dahlen F. A. 
Published: September 2021

Abstract
The effect of a homogeneous anisotropic initial stress on the propagation of infinitesimal amplitude elastic body waves in a perfectly elastic, homogeneous medium is investigated. If the medium is inherently isotropic in the reference configuration and if the magnitude τ0 of the deviatoric part of the initial static stress is small compared to the rigidity μ of the medium, then the apparent body-wave velocities of P waves are unaffected by the initial stress to first order in τ0/μ. The apparent body-wave velocities of S waves are rendered anisotropic to first order, and this effect is described explicitly. It is concluded that the direct effect of an anisotropic initial stress cannot contribute appreciably to the observed velocity anisotropy of horizontally propagating P waves in the oceanic upper mantle. Those observations require an inherent elastic anisotropy of the oceanic uppermantle material.
An earth-flattening transformation for waves from a point source
Authors: Hill David P. 
Published: September 2021

Abstract
An earth-flattening transformation is developed for wave-propagation problems that can be formulated in terms of uncoupled scalar Helmholtz equations. Through the transformation, wave problems in isotropic, spherically symmetric media with a specified radial heterogeneity can be expressed in terms of a flat geometry with a suitably vertical heterogeneity. The transformation is exact for homogeneous (no source) problems and is useful for normal mode studies. When a point source of waves is present, the earth-flattening transformation together with the Watson transform converts the reflected wave field from a sum over discrete, spherical eigenfunctions to an integral over continuous wave numbers in a flat geometry. The far-field form of this integral shares many properties with the Weyl integral and is useful for body-wave studies in a spherical earth.
Dilatancy, pore fluids, and premonitory variations of ts/tp travel times
Authors: Nur Amos 
Published: September 2021

Abstract
Nerseov et al. (1969) found that the travel-time ratio of shear and compressional waves, ξ = ts/tp varies prior to the occurrence of earthquakes in the Garm region, USSR. Laboratory results indicate that the decrease of ξ can result from dilatancy of rocks around the focal zone. The subsequent increase of ξ, which terminates with an earthquake, can be caused by the flow of ground water into the dilated zone. The increasing pore pressure weakens the rock and leads to the observed failure.
Estimated earthquake probabilities in the north circum-Pacific area
Authors: Shakal A. F. , Willis D. E. 
Published: September 2021

abstractGumbel's extreme value theory is applied to the estimation of probabilities of occurrence and return periods for large earthquakes in the north circum-Pacific area, using earthquake data from 1930 through 1971. The probability model of Epstein and Lomnitz is discussed with reference to Gumbel's extreme value theory. Estimated probabilities and expected extremes within individual tectonic blocks are calculated and compared. The area of the Aleutian Arc between 155°W and 167°W is found to have about an 80 per cent probability of an Ms ≧ 8 earthquake by 1980.
Stick-slip propagation velocity and seismic source mechanism
Authors: Wu Francis T. , Thomson K. C. , Kuenzler H. 
Published: September 2021

abstractEarthquakes, at least the shallow ones, take place along pre-existing fault planes. The controlling factor is, therefore, friction, and the fault growth process resembles that of stick-slip propagation. We have simulated this process in a two-dimensional model. It is found that propagation velocity can range from sub-shear to 1.1 Vs (the latter is not a limiting value).
Determination of the seismograph phase response from the amplitude response
Authors: Bolduc P. M. , Ellis R. M. , Russell R. D. 
Published: September 2021

abstract
Determination of the phase response of a minimum-phase seismic system directly from the amplitude response by the Hilbert transform is investigated. The error by this technique is found to be less than 2° with the major source of inaccuracy being the uncertainties in the amplitude data. This technique is useful for rapid determination of the phase response if the amplitude response is known.
Seismicity and tectonics of western Venezuela
Authors: Dewey James W. 
Published: September 2021

abstract
New seismicity data on western Venezuela and northeastern Colombia are presented. Teleseismically recorded earthquakes from 1930 through 1970 have been relocated by Joint Hypocenter Determination (JHD) or with source-station adjustments calculated by JHD. Additionally, 540 days of recording have been obtained with local seismographs installed near the Boconó Fault.
The most intense shallow activity occurred north and south of the Tachira Depression along the eastern flank of the Cordillera Oriental of Colombia. The Boconó Fault Zone is seismically active; small shallow shocks were recorded in it by the local stations. Shallow earthquakes also occur in the Cordillera de Mérida away from the Boconó Fault.
The new hypocenters for the intermediate-depth Bucaramanga earthquakes define a smaller source volume than defined by previously computed hypocenters. A previously inferred southward-dipping seismic zone near Bucaramanga is probably spurious, a consequence of correlation between errors in latitude and errors in depth. If one assumes that these intermediate-depth earthquakes lie on a single lithospheric slab, that slab strikes approximately north and dips to the east.
The distribution of hypocenters and focal mechanisms support the platetectonic hypothesis that the present tectonics of northwestern Venezuela are a result of eastward motion of the Caribbean plate with respect to the South American plate. The principal interface between these two plates may have changed within the last 5 m.y. from a zone of underthrusting west of the Sierra de Perija to the predominantly right-lateral Boconó Fault Zone.
Ambient earth motion in the period range from 0.1 to 2560 sec
Authors: Fix James E. 
Published: September 2021

abstract
Amplitude spectral density of the ambient earth motion in the vertical and horizontal directions at a quiet site are given in graphical and tabular form over the five decades of period from 0.1 to 2560 sec. Comparison of these spectra in the period range between 0.1 and 3 sec with the Brune and Oliver (1959) minimum curve and in the period range between 10 and 100 sec with spectra from the mines at Las Cruces, New Mexico, and Ogdensburg, New Jersey, indicate that in these period ranges the spectra are representative of the quietest seismograph stations presently known. These spectra can serve as a guide for seismologists and other scientists interested in the quiescent vibrations of the ground.
Potential Utilization Analysis of River Waste in Jakarta, Indonesia
Authors: Safira Rahajeng Hasna , Sari Mega Mutiara , Notodarmojo Suprihanto , Inoue Takanobu , Harryes Regil Kentaurus 
Published: September 2021

There are still many people in Jakarta who throw their garbage into the river, resulting Jakarta city never being absent from the problems of river water pollution and flooding. Pesanggrahan River and Grogol River are some of the big river surrounded by high popullation area. All waste originating from the Pesanggrahan River and the Grogol River is dumped into the Bantar Gebang Landfill. This study aimed to reduce waste entering landfills are by making use of waste that still has economic value.The method used in decision making from various alternatives of the river waste utilization are utility theory and compromise programming. It takes planning to find out the composition and generation of solid waste from those rivers and to determine the potential use of river waste and the action to minimize and handle the river waste. Utilization of river waste that can be applied based on the composition of most waste is open windrow composting and plastic shredding. It is important to concern about river waste since Indonesia has various polluted river, especially by solid waste. By implementing a good river waste utilization, the waste that enters the landfill will be reduced and in line with reduced pollution to the aquatic environment.
Keywords: Solid waste; Water; Generation; Composition; Utilization

Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember
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Flash Flood Susceptibility Mapping at Andungbiru Watershed, East Java Using AHP-Information Weighted Method
Authors: Handini Devi Ratna , Hidayah Entin , Halik Gusfan 
Published: September 2021

Flash floods are among the most frequent natural disasters caused by heavy rain associated with a severe thunderstorm, which leads to social and economic losses in infrastructure and agriculture. Therefore, this research aims to map flash flood potential susceptibility (FFPS) in the Pekalen watershed, using Geographic Information System (GIS) technology and statistical analysis to reduce the risk of flooding. The opinion and experience of an expert on the weight assessment method were carried out using the Analytical Hierarchy Process (AHP). Furthermore, the probability statistical methods and GIS were used in flash flood areas in the Pekalen watershed in Andungbiru, Probolinggo village. This study was carried out using geomorphological factors, namely elevation, slope, stream power index, and topographic wetness index, with a resolution of 30 m. Thematic map scale of the land use, river density, distance to the river, rainfall, and geology is in the ratio of is in a ratio of 1:25.000. Imagery processing was carried out using Landsat 8 30 m x 30 m resolution imagery, such as the Normalized Difference Vegetation Index. The result showed that the model map of FFPS obtained low 8%, low 23%, moderate 27%, moderate to high 26%, high 13%, and very high 2% index values. The next stage of modeling analysis led to validation using statistic receiver operating Characteristic Curve (ROC) of area Under Curve (AUC) with a value of 90.15. In conclusion, the factors that significantly trigger flash floods are distance to the river, land use, and slope.

Keywords: AHP-weighted; information content; FFSP; GIS; Geomorphology
Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember

This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License