bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic Noise Recorded by Telecommunication Fiber Optics Reveals the Impact of COVID-19 Measures on Human Activity
Authors: Shen Junzhu , Zhu Tieyuan 
Published: June 2021

Abstract
Quantifying the response of human activity to different COVID-19 measures may serve as a potential way to evaluate the effectiveness of the measures and optimize them. Recent studies reported that seismic noise reduction caused by limited human activity due to the COVID-19 lockdown had been observed with seismometers. However, it is difficult for the current seismic infrastructure in urban cities to characterize spatiotemporal seismic noise during the post-COVID-19 lockdown, because of their sparse distribution. Here, we show key connections between progressive COVID-19 measures and spatiotemporal seismic noise changes recorded by a distributed acoustic sensing (DAS) array deployed in State College, Pennsylvania. We first show a spatiotemporal seismic noise reduction (up to 90%) corresponding to reduced human activity in different city blocks during the stay-at-home period. We also show partial noise recovery corresponding to increased road traffic and industrial machinery in phase yellow and phase green of the lockdown. Nonrecovery seismic noise in the 0.01–10 Hz band suggests the low level of pedestrian movement during phase yellow and phase green. According to a linear correlation between Google mobility change and seismic noise change, we emphasize that DAS recordings using city-wide fiber optics could provide a way for quantifying the impact of COVID-19 measures on human activity in different blocks.
Finite difference analysis of Rayleigh wave scattering at a trench
Authors: Fuyuki Masahiko , Matsumoto Yoshiro 
Published: June 2021

abstractA finite difference scheme with the improved treatment of boundary conditions at corners and with the introduction of the absorbing boundary conditions at computational edges is applied to the analysis of Rayleigh wave scattering at a trench ditched on the surface of an elastic half-space. Complex transmission and reflection coefficients are calculated from the surface waveforms at a given moment and are compared with the experimental and theoretical predictions. In order to investigate the effect of converted waves, the complex transmission coefficient along a step is calculated from the time series waveforms at observation points with a fixed incident angle to the free surface.
The wave front in a homogeneous anisotropic medium
Authors: Yedlin M. J. 
Published: June 2021

abstractA simple geometric construction is derived for the shape of the wave front in a homogeneous anisotropic medium. It is shown to be equivalent to the intuitive method of constructing a wave front using Huygen's principle.Although this construction has been referred to and tersely described in the literature (Musgrave, 1970; Kraut, 1963; Duff, 1960), it is instructive to demonstrate its relationship to the common notion of the wave front obtained via consideration of the group velocity. The wave front is shown to be the polar reciprocal of the slowness surface (the dispersion relation at constant frequency). An appreciation of the pole-polar correspondence between the two surfaces allows quick inference of some of the important features of the wave front in a homogeneous anisotropic medium.
Location of earthquake swarm events near Palmdale, California, using a linear gradient velocity model
Authors: Drowley Dayna Salter , McNally Karen C. 
Published: June 2021

abstractA series of small earthquakes (0.5 ≦ ML ≦ 3.0) along a 60-km segment of the San Andreas Fault in the vicinity of Palmdale, California, has been recorded since 1976 by an array operated by the California Institute of Technology. The events were analyzed in two steps. First, travel-time data from four regionally well-recorded events (ML = 2.2, 2.8, 3.0, 2.8) were inverted using a nonlinear least-squares algorithm to obtain a local velocity model consisting of an upper crustal layer with linearly increasing velocity in dipping contact with a constant velocity half-space. Hypocenters of over 150 events were relocated using this velocity model. Most of the events are clustered between the mapped traces of the San Andreas and Punchbowl faults; however, there has been a migration of activity along the San Andreas Fault. Activity which began in a 5-km cluster has expanded during a 2-yr period to fill a 60-km segment of the fault.
Tasmanian seismicity—natural and reservoir-induced
Authors: Shirley J. E. 
Published: June 2021

abstractThe Tasmania University Seismic Net currently operates eight stations in Tasmania. Telemetered data are recorded at the University in Hobart on chart and on magnetic tape. The net is capable of detecting events with M &gt; 0.8, and the epicenters of these events can be reliably determined over an area of 40,000 km2 or approximately 60 per cent of the island. There are at present approximately 100 events located per year of which 80 per cent can be assigned magnitudes. Approximately 20 per cent of these events have M ≧ 2.0 with 5 per cent M ≧ 3.0.Much of the seismic activity can be correlated with major geological features. There is a direct correlation between the increased seismicity in the Gordon River Power Development storage area and the water load of this 13.5 × 109 tonne water storage.
Short-term tilt anomalies preceding local earthquakes near San Jose, California
Authors: Mortensen C. E. , Iwatsubo E. Y. 
Published: June 2021

abstractA tilt anomaly preceded a pair of earthquakes (ML = 4.2, origin time 0014 UTC, and ML = 3.9, origin time 0018 UTC, both on 29 August 1978) on the Calaveras Fault near San Jose, California. These earthquakes occurred at hypocentral depths of 8.5 and 9.0 km, respectively, and were located 6.7 and 5.2 km northwest of the Mt. Hamilton tiltmeter site. The anomaly is similar in shape and time scale to signals observed on other tiltmeters at the times of recorded surface creep events. The anomaly began approximately 40 hr before the earthquake pair and consisted of gradual down-to-the-east tilting followed by rapid tilting down-to-the-north-northeast at a rate of 12 μrad/hr. This was followed by 1 hr of rapid down-to-the-east tilting amounting to 1.5 μrad. The maximum peak tilt of 10.6 μrad down-to-the-northeast was followed by gradual decelerating tilting down-to-the-southwest constituting partial recovery. An anomaly of nearly identical form, but smaller in amplitude and duration, preceded an ML = 2.2 aftershock on 5 September 1978. Other nearby earthquakes as large as ML = 4.7 have occurred without accompanying creep-like signals. A similar, but a much smaller (0.74 μrad) creep-event-like signal preceded an ML = 3.5 earthquake with epicenter 3 km east of the Black Mountain tiltmeter site. In general, however, short-term tilt anomalies such as these are not observed to precede local earthquakes within the central California tiltmeter network. The tilt signal preceding the 29 August earthquake pair may be interpreted in terms of a model of a propagating creep event, at depth, associated with seismic failure at a “stuck” patch on the fault. However, the data are not adequate to constrain the model sufficiently to constitute a test of the hypothesis.
Earthquake source mechanism determination by use of body-wave amplitudes—An application to Swedish earthquakes
Authors: Slunga Ragnar 
Published: June 2021

abstractA method for earthquake source studies based on a combined use of polarity and amplitude observations is proposed. It makes use of the impulses of the observed body waves to avoid the introduction of additional source parameters besides the orientation angles and seismic moments.A statistical model is proposed and the method is applied to five small earthquakes in Sweden recorded by 3 to 5 stations in the distance range of 20 to 100 km. The seismic moments of these earthquakes are in the range of 0.6 to 10 × 1011 N-m (1 N-m = 107 dyne-cm).The resulting mechanisms are statistically significant and well defined in spite of the fact that for four of the earthquakes, only two or less polarities are used. Furthermore, the solutions are close to the mechanism of the major (Mo = 3.5 × 1015 N-m) earthquake in the Gulf of Finland 1976. They all indicate horizontal principal compressive stresses in the sector E-W to SSE-NNW.The successful use of amplitude observations presented in this paper shows that source mechanism inversion can be made based on recordings at only a very few close stations.
Transmitting boundaries: A closed-form comparison
Authors: Kausel Eduardo , Tassoulas John L. 
Published: June 2021

abstractSeveral transmitting boundaries which have been proposed for the numerical analysis of problems of wave propagation in continua of infinite extent are reviewed. They are grouped into three broad classes: (1) elementary boundaries (Dirichlet or Neumann boundary conditions); (2) highly absorbing local boundaries; and (3) consistent transmitting boundaries. A closed-form comparison for the problem of time-harmonic antiplane line load on a stratum shows that elementary boundaries produce strong reflections, local boundaries have good absorption characteristics, and consistent transmitting boundaries are perfect absorbers.
A constraint on the earth's lateral heterogeneity from the scattering of spheroidal modeQ−1 measurements
Authors: Sleep Norman H. , Geller Robert J. , Stein Seth 
Published: June 2021

abstractWe conduct a probabilistic analysis of the scattering of normal mode Q−1 measurements caused by the multiplet splitting from the earth's lateral heterogeneity. We apply our probabilistic results to a data set of unstacked Q−1 measurements for fundamental spheroidal modes from 0S13 through 0S28. Multiplet broadening of only 14 × 10−4 of the central frequency is sufficient to account for the scatter of the observed data. The observed scatter of Q−1 data is caused by a combination of three effects: lateral heterogeneity of density and velocities, actual lateral heterogeneity of Q−1 in the earth, and measurement error. The last two effects can only reduce the amount of lateral heterogeneity of density and velocities which is required to produce the observed scatter. Thus, by attributing the entire multiplet broadening to lateral heterogeneity of elastic properties, we can obtain an upper bound on its effect. It seems reasonable to assume that the maximum fraction of lateral heterogeneity in the mantle at the depths sampled by these modes (roughly from the surface to 1000 km deep) is on the same order (14 × 10−4) as the maximum multiplet broadening found by our analysis.
Spatial variation of crustal seismic velocities in southern California
Authors: Ergas Raymond A. , Jackson David D. 
Published: June 2021

abstractArrival-time data for local earthquakes were used to study lateral velocity variations and error statistics for southern California. Crustal P velocities averaged over the major geomorphic provinces vary by only a few per cent. Regions of relatively high velocity include the Peninsular ranges, the Imperial valley, the Pomona basin, and the Colorado desert. The Santa Monica, southern Sierra, San Bernardino, and San Jacinto mountains are relatively slow, as is the offshore area. Near-surface station delays, which are unknown to within several tenths of a second, are a major source of uncertainty in the regional velocities.Arrival-time errors include two types: (1) small errors caused by imperfect timing and unmodeled velocity variations; and (2) larger errors apparently caused by improper identification of arrivals and by blunders. We found no reliable way to identify the latter errors unless they result in large arrival-time residuals. For a strongly edited catalog, the variance of arrival-time residuals appears to increase linearly with epicentral distance, as predicted for wave propagation in a randomly heterogeneous medium. The variance of residuals is strongly station dependent. Residuals are nearly Gaussian within the 70 per cent confidence interval, but not outside this interval. The 95 per cent confidence limit occurs at about three standard deviations.
Multi-mode analysis of Rayleigh-type Lg. Part 2. Application to southern California and the northwestern Sierra Nevada
Authors: Cara Michel , Minster J. Bernard , Le Bras Ronan 
Published: June 2021

abstract
The UC diagram technique described in the companion paper (Part 1), is applied to nine sets of Lg phases recorded through the CEDAR system in southern California, and two sets of Lg phases recorded along the northwestern margin of the Sierra Nevada. A clear image of the signal is obtained in time-frequency-wavenumber space, and we discuss in particular observations at 2.5-sec period, for events 200 to 300 km outside the profiles. From the gross features of UC diagrams we conclude that a representation of Lg as a single coherent multi-mode wave train is oversimplified in the case of southern California but is more appropriate for the Sierra block. In southern California, peaks observed at group velocities smaller than 3.2 km/sec are not predicted by realistic crustal models of the area, and are probably due to lateral heterogeneities effects such as mode conversion and multipathing. On the other hand, for group velocities between 3.2 and 3.6 km/sec, peaks observed in either area can generally be interpreted in terms of overtones excited at the source and propagating through spatially averaged structures, although care must be taken to monitor the stability of the algorithm on actual short-period records.
Magnitude calibration of the Central Minnesota Seismic Array
Authors: Greenhalgh S. A. , Mosher C. C. , Mooney H. M. 
Published: June 2021

abstractMagnitude calibration for the Central Minnesota Seismic Array presents special problems because the infrequuent local and near-regional earthquake are usually too small to be recorded at teleseismic distances. Two procedures have been applied. The first uses teleseisms recorded by the array for which independent magnitudes are available. The second uses large near-regional mine blasts to determine the attenuation rate for short-period P waves in the upper crust, together with Evernden's (1970) magnitude-charge size relationship.The teleseismic correlations establish that the individual stations of the array yield consistent magnitudes, that the P wave amplitudes behave predictably with respect to epicentral distance and azimuth, but that a magnitude-dependent bias must be removed.Measured ground amplitudes for mine blasts are found to be proportional to total charge size to the power 1.0. Using this value, we find amplitude attenuation proportional to D−B for distance D in kilometers, with best fit given by B = 2.57 for P waves. The final local magnitude scale for D up to 250 km takes the formm b = 2.57 log ⁡ D + log ⁡ A − 3.97.
The times of origin and depths of focus of intermediate and deep focus earthquakes: Model calculations
Authors: Hales A. L. , Muirhead K. J. , Maki-Lopez L. 
Published: June 2021

abstractTwo methods for determining the time of origin, depth of focus, and the average velocities from the focus to the surface are described. The first stage in the first method is to determine the time of origin using a modification of the Wadati method. As was pointed out in 1973 by Kisslinger and Engdahl, the relation between (ts − tp and tp is nonlinear and it is necessary to allow for this nonlinearity by including a term in tp2 in the analysis. Thereafter the depth of focus and the average velocity can be found by a modification of the procedure used to determine the depth to a reflector in seismic reflection prospecting. It is necessary to allow for the sphericity of the Earth in this analysis.In the second method, the depth of focus is determined first by analyzing (ts − tp)2 as a function of x2, x being the epicentral distance. The average velocity of separation of S and P waves is also determined at this stage. Thereafter the time of origin and the average P and S velocities are determined. The results of the analysis of the calculated travel times for three models show that systematic errors in the depth of focus using these procedures are less than 2 km over the depth range of 60 to 640 km.Preliminary results of the analysis of a limited set of Japanese earthquakes by these methods give estimates of depth smaller than those given by ISC for depths less than 300 km. For deeper earthquakes, these methods give foci deeper than the ISC, but in these cases the observations close to the epicenter are inadequate for reliable analysis.
Microseismicity in the mid-St. Lawrence Valley Charlevoix zone, Québec
Authors: Anglin F. , Buchbinder G. 
Published: June 2021

abstract
Previous seismicity studies of the Charlevoix zone of the mid-St. Lawrence Valley have defined the extent of the active zone. Continued monitoring of this zone has yielded more hypocenters that, together with the previous data, give a more detailed picture of the hypocentral distribution of the microactivity. A more definite correlation can now be made with the known structure in this region and the faults of the St. Lawrence VAlley in general.
The cumulative data permit a definition of lateral boundaries of the seismic activity, range of focal depths, and anomalous nonseismic zones. It is also possible to make a correlation with the normal faults that were probably associated with the paleorifting of the St. Lawrence Valley but are now under compression. In this seismically active region, part of these preexisting partially sealed faults were most likely weakened again at the time of formation of the Charlevoix impact structure.
Comparison of theS/Nratios of low-frequency hydrophones and geophones as a function of ocean depth
Authors: Brocher Thomas M. , Iwatake Brian T. , Gettrust Joseph F. , Sutton George H. , Frazer L. Neil 
Published: June 2021

abstractThe pressures and particle velocities of sediment-borne signals were recorded over a 9-day period by an array of telemetered ocean-bottom seismometers positioned on the continental margin off Nova Scotia. The telemetered ocean-bottom seismometer packages, which appear to have been very well coupled to the sediments, contained three orthogonal geophones and a hydrophone. The bandwidth of all sensors was 1 to 30 Hz. Analysis of the refraction data shows that the vertical geophones have the best S/N ratio for the sediment-borne signals at all recording depths (67, 140, and 1301 m) and nearly all ranges. The S/N ratio increases with increasing sensor depth for equivalent weather conditions. Stoneley and Love waves detected on the Scotian shelf (67-m depth) are efficient modes for the propagation of noise.
Ecotourism in Indonesia: Local Community Involvement and The Affecting Factors
Authors: Kia Zakia 
Published: June 2021

Travel and tourism have become a fast-growing industry and a major source of income for many developing countries (Wood, 2002), including Indonesia. Approximately 35% of major nature tourism product portfolio is ecotourism (Kementerian Pariwisata dan Ekonomi Kreatif, 2019). Ecotourism development is based on the awareness of understanding in every environment condition which oriented in conservation and concern of the local culture as well as local civilization. Hence, the existence of community interaction is a guarantee to the sustainability of ecotourism development (Damanik, 2013; Wood, 2002). Many benefits offered by the concept of ecotourism, does not keep this concept away from several critics, related to the low of local community involvement in ecotourism management. This study aims to analyze the local community involvement as well as the affecting factors in managing the ecotourism in Indonesia by systematically reviewing 29 articles published in Sinta Ristekdikti’s accredited journals with the qualifications of Sinta 1 and Sinta 2. The discussion about local community involvement will be reviewed from the ecotourism planning level, participation in ecotourism development implementation and participation in its use (Lukman, 2017). Meanwhile, the affecting factors will be analyzed from the operational, structural and cultural perspective. The results show that the involvement of local communities in ecotourism management in Indonesia is still limited to the level of utilization. From the operational perspective, limits to local community involvement are come from limited information availability about ecotourism to local communities, centralized tourism management and the lack of coordination among stakeholders. Limited number of trained human resources, legal system that does not support the participatory practices, the uncooperative attitude of professionals and the dominance of local elite are still become the limitations to local community involvement from a structural perspective. Meanwhile, cultural barriers include apathy and a low level of public awareness of the potential benefit of ecotourism in their area. We can conclude that the empowerment efforts to local community in ecotourism destinations must be further improved. Educating the local community to understand their rights, informing them about the ecotourism management in their area would be the right first step to execute, because due to the lack of knowledge and information they have, frequently triggers disturbances from the local community which actually will thwart the ecotourism purposes.
A study to establish the prevalence of urinary tract infection in preterm labour
Authors: Kruthipati Rashmi , Chethan Radhika , Shiva Anitha Gabbalkaje , Suresh Sukanya , Krishnappa Tejeswini Kolige 
Published: June 2021

Background: Urinary tract infection (UTI) is one of the many etiological factors of preterm labour. Preterm labour is the onset of labour after 28 weeks and before 37 weeks of gestation. Preterm labour is a significant cause for perinatal morbidity and mortality. Hence early diagnosis and management of etiological factors is necessary. The most common bacterial infection encountered during pregnancy is UTIs. Early detection and management of UTIs may effectively prevent complications of preterm labour including preterm birth. Aims and objectives of the study was to estimate the prevalence of UTIs in preterm labour.Methods: cross sectional study with a total of 250 patients carried out in the department of obstetrics and gynaecology, Vanivilas hospital, BMCRI for a period of 6 moths-Aug 2019-Feb 2020. Patients in preterm labour i.e., cervical dilatation ≥1 cm, cervical effacement ≥80% with true labour pains were included in the study after taken informed consent form the patient. Detailed clinical history including age of patient, level of education, duration of antenatal care, parity, and obstetrical history was taken. Gestational age was calculated by LMP or early ultrasound. General examination, systemic examination and obstetric examination was done. Routine investigations were done along with clean catch midstream urine sample in a sterile container. Two samples were collected: 1st sample for microscopic examination, 2nd sample for culture and sensitivity.Conclusions: Untreated UTI can be associated with obstetric complications. The most common bacterial infection during pregnancy is UTIs. All women should be screened for UTI at the first antenatal visit. Once diagnosed it should be promptly treated with suitable antibiotic which is sensitive yet safest.