bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disaggregation of seismic hazard
Authors: Bazzurro Paolo , Allin Cornell C. 
Published: August 2021

AbstractProbabilistic seismic hazard analysis (PSHA) integrates over all potential earthquake occurrences and ground motions to estimate the mean frequency of exceedance of any given spectral acceleration at the site. For improved communication and insights, it is becoming common practice to display the relative contributions to that hazard from the range of values of magnitude, M, distance, R, and epsilon, ɛ, the number of standard deviations from the median ground motion as predicted by an attenuation equation.The proposed disaggregation procedures, while conceptually similar, differ in several important points that are often not reported by the researchers and not appreciated by the users. We discuss here such issues, for example, definition of the probability distribution to be disaggregated, different disaggregation techniques, disaggregation of R versus ln R, and the effects of different binning strategies on the results. Misconception of these details may lead to unintended interpretations of the relative contributions to hazard.Finally, we propose to improve the disaggregation process by displaying hazard contributions in terms of not R, but latitude, longitude, as well as M and ɛ. This permits a display directly on a typical map of the faults of the surrounding area and hence enables one to identify hazard-dominating scenario events and to associate them with one or more specific faults, rather than a given distance. This information makes it possible to account for other seismic source characteristics, such as rupture mechanism and near-source effects, during selection of scenario-based ground-motion time histories for structural analysis.
Inferred seismic fault associated with the 1998 M = 6.2 Zhangbei-Shanyi earthquake, Hebei Province, China
Authors: Lin Aiming , Zhao Guochun , Zhao Guozhe , Xu Xiwei 
Published: August 2021

Abstract
The shallow, Ms = 6.2, 1998 Zhangbei-Shanyi earthquake that affected the northwest region of Beijing, China, occurred at the intersection of two active fault zones, located on the north and east edges of the Ordos tableland. A detailed map of the intensity distribution of damaged building shows that the most damaged area was centered 8 to 10 km away from the epicenter, including an ellipsoidal region with a strike of NNE, where more than 70 to 90% of buildings were destroyed. Many chimneys and gate pillars were broken and fell toward the SSE-SSW direction in the western side of the most damaged area and to the NNE-NNW direction in the eastern side. Aftershocks were also concentrated in the most damaged area. It is inferred that the boundary of the downfallen direction change is the surface trace of the seismic fault. Based on the seismic data, the distribution of damaged buildings, and the downfallen directions of 70 chimneys and gate pillars, it is identified that the seismic fault is a thrust fault striking NNE and dipping 40° to 50° northwest with a large right-lateral displacement component.
A mutually consistent seismic-hazard source model for southern California
Authors: Field Edward H. , Jackson David D. , Dolan James F. 
Published: August 2021

AbstractA previous attempt to integrate geological, geodetic, and observed seismicity data into a probabilistic-hazard source model predicted a rate of magnitude 6 to 7 earthquakes significantly greater than that observed historically. One explanation was that the discrepancy, or apparent earthquake deficit, is an artifact of the upper magnitude limit built into the model. This was controversial, however, because removing the discrepancy required earthquakes larger than are seen in the geological record and larger than implied from empirical relationships between fault dimension and magnitude. Although several articles have addressed this issue, an alternative, integrated source model without an apparent deficit has not yet appeared. We present a simple geologically based approach for constructing such a model that agrees well with the historical record and does not invoke any unsubstantiated phenomena. The following factors are found to be influential: the b-value and minimum magnitude applied to Gutenberg-Richter seismicity; the percentage of moment released in characteristic earthquakes; a round-off error in the moment-magnitude definition; bias due to historical catalog incompleteness; careful adherence to the conservation of seismic moment rate; uncertainty in magnitude estimates obtained from empirical regressions; allowing multi-segment ruptures (cascades); and the time dependence of recurrence rates. The previous apparent deficit is shown to have resulted from a combination of these factors. None alone caused the problem nor solves it. The model presented here is relatively robust with respect to these factors.
Discrimination information in phase amplitude thresholds with application to western China regional data
Authors: Anderson Dale N. , Taylor Steven R. , Anderson Kevin K. 
Published: August 2021

AbstractThis article develops a regional seismic discrimination method using information inherent in phase amplitudes that are unmeasurable due to small signal amplitudes and high noise levels. The method, quadratic negative evidence discrimination (QNED), is an enhancement to the teleseismic techniques proposed by Elvers (1974) and is extended to regional discrimination. The method presented in this article is developed for a single seismic station and makes use of the empirical evidence in the regional Pg versus Lg discriminant (see Pomeroy et al., 1983). We develop the equations necessary to compute the station-specific, missed-explosion, and false-alarm error rates. These error rates depend on the required minimum signal-to-noise ratio (S/N) and can be adjusted, within limits, to desired levels. We also show that these equations are an accurate assessment of the errors in seismic discrimination. We propose that many of the current approaches to assessing seismic discrimination errors are often overly optimistic. For some applications, this disparity can be significant. For an application to Western China regional data [Pg versus Lg (1.5 to 3 Hz)], a widely used estimate of the missed-explosion error rate is 20%, leading to the perception that explosions can be identified with an accuracy rate of 80%. A proper accounting of the missed-explosion error rate, using QNED, shows that explosions can be identified with accuracy rate of only 73%.
Characterization of fractures in shallow granite from the modeling of the anisotropy and attenuation of seismic waves
Authors: Kelner Sylvie , Bouchon Michel , Coutant Olivier 
Published: August 2021

AbstractWe try to characterize the fracturing of the anisotropic shallow granite (&lt;250 m) present at Garner Valley, southern California. The shear-wave splitting observed on a downhole seismic array installed there (Archuleta et al., 1992) is modeled by performing numerical simulations of propagation of P and SV waves in 2D fractured media. The calculations are performed using a boundary integral equation method, which takes into account multiple scattering and full crack diffraction. The value of the time delay measured at Garner Valley between the fast S wave and the slow S wave is well reproduced for different models of fractured media. In order to differentiate between these models, we also measure and calculate the attenuation of the transmitted S waves. From the comparison between the observations and the numerical simulations, we conclude and infer the following: (1) The presence of fractures in granite explains the seismic anisotropy and attenuation observed at Garner Valley. (2) The cracks and fractures are nearly vertical and are oriented in a north-south direction. (3) There is no characteristic crack length, but rather, the crack length distribution seems to be fractal. (4) The density of fractures present in the shallow granite at Garner Valley is about 10−4 representing the total volume of the fractures over the total volume of the fractured zone.
A Monte Carlo approach to seismic hazard analysis
Authors: Ebel John E. , Kafka Alan L. 
Published: August 2021

AbstractWe have developed a Monte Carlo methodology for the estimation of seismic hazard at a site or across an area. This method uses a multitudinous resampling of an earthquake catalog, perhaps supplemented by parametric models, to construct synthetic earthquake catalogs and then to find earthquake ground motions from which the hazard values are found. Large earthquakes extrapolated from a Gutenberg-Richter recurrence relation and characteristic earthquakes can be included in the analysis. For the ground motion attenuation with distance, the method can use either a set of observed ground motion observations from which estimates are randomly selected, a table of ground motion values as a function of epicentral distance and magnitude, or a parametric ground motion attenuation relation. The method has been tested for sites in New England using an earthquake catalog for the northeastern United States and southeastern Canada, and it yields reasonable ground motions at standard seismic hazard values. This is true both when published ground motion attenuation relations and when a dataset of observed peak acceleration observations are used to compute the ground motion attenuation with distance. The hazard values depend to some extent on the duration of the synthetic catalog and the specific ground motion attenuation used, and the uncertainty in the ground motions increases with decreasing hazard probability. The program gives peak accelerations that are comparable to those of the 1996 U.S. national seismic hazard maps. The method can be adapted to compute seismic hazard for cases where there are temporal or spatial variations in earthquake occurrence rates or source parameters.
Attenuation and excitation of three-component ground motion in southern California
Authors: Raoof M. , Herrmann R. B. , Malagnini L. 
Published: August 2021

AbstractGround motion attenuation with distance and the variation of excitation with magnitude are parameterized using three-component, 0.25 to 5.0-Hz earthquake ground motions recorded in the distance range of 15-500 km for southern California to define a consistent model that describes both peak ground motion and Fourier spectra observations. The data set consists of 820 three-component TERRAscope recordings from 140 earthquakes, recorded at 17 stations, with moment magnitudes between 3.1 and 6.7. Regression analysis uses a simple model to relate the logarithm of measured ground motion to excitation, site, and propagation effects. The peak motions are Fourier velocity spectra and peak velocities in selected narrow bandpass-filtered frequency ranges. Regression results for Fourier amplitude spectra and peak velocities are used to define a piecewise continuous geometrical spreading function, frequency dependent Q(f), and a distance dependent duration that can be used with random vibration theory (RVT) or stochastic simulations to predict other characteristics of the ground motion.The duration results indicate that both the variation of the duration data with distance and its scattering decrease with increasing frequency. The ratio of horizontal to vertical component site terms is about √2 for all frequencies. However, this ratio is near unity for rock sites and is larger for soil sites.Simple modeling indicates that the Fourier velocity spectra are best fit by bilinear geometrical spreading of r−1 for r &lt; 40 km and r−1/2 for r &gt; 40 km. The frequency-dependent quality factor is Q(f) = 180f0.45 for each of the three components and also for the combined three-component data sets. The T5%-75% duration window provides good agreement between observed and RVT predicted peak values.
Seismic analysis of the 7 January 1998 Chemical plant explosion at Kean Canyon, Nevada
Authors: Ichinose Gene A. , Smith Kenneth D. , Anderson John G. 
Published: August 2021

AbstractAn accident at the Sierra Chemical Company Kean Canyon plant, 16 km east of Reno, Nevada, resulted in two explosions 3.52 sec apart that devastated the facility. An investigation into a possible cause for the accident required the determination of the chronological order of the explosions. We resolved the high-precision relative locations and chronology of the explosions using a cross-correlation method applied to both seismic and air waves. The difference in relative arrival times of air waves between the explosions indicated that the first explosion occurred at the northern site. We then determined two station centroid separations between explosions, which average about 73 m with uncertainties ranging from ± 17 to 41 m depending on the alignment of station pairs. We estimated a centroid separation of 80 m using P waves with a larger uncertainty of ± 340 m. We performed a grid search for an optimal separation and the azimuth by combining air-wave arrivals from three station pairs. The best solution for the relative location of the second explosion is 73.2 m S35°E from the first explosion. This estimate is well within the uncertainties of the survey by the U.S. Chemical Safety and Hazard Investigation Board (CSB). The CSB reported a separation of approximately 76.2 m S33°E. The spectral amplitudes of P waves are 3 to 4 times higher for the second explosion relative to the first explosion, but the air waves have similar spectral amplitudes. We suggest that this difference is due to the partitioning of energy between the ground and air caused by downward directivity at the southern explosion, and upward directivity at the northern explosion. This is consistent with the absence of a crater for the first explosion and a 1.8-m-deep crater for the second explosion.
Source parameter determination of local earthquakes in Korea using moment tensor inversion of single station data
Authors: Kim So Gu , Kraeva Nadeja 
Published: August 2021

AbstractThe purpose of this investigation is to determine source parameters such as focal mechanism, seismic moment, moment magnitude, and source depth from recent small earthquakes in the Korcan Peninsula using broadband records of three-component single station. It is very important and worthwhile to use a three-component single station in Korea because for most Korean earthquakes it is not possible to read enough first motions of P-wave arrivals because of the poor coverage of the seismic network and the small size (ML 5.0 or less) of the events. Furthermore the recent installation of the very broadband seismic stations in Korea and use of a 3D tomography technique can enhance moment tensor inversion to determine the source parameters of small earthquakes (ML 5.0 or less) that occur at near-regional distances (Δ ≤ 500 km).The focal solution for the Youngwol earthquake of 13 December 1996 is found to be a right-lateral strike slip event with a NE strike, and the Kyongju earthquake of 25 June 1997 is found to be an oblique reverse fault with a slight component of left-lateral slip in the SE direction.
Worldwide doublets of large shallow earthquakes
Authors: Kagan Y. Y. , Jackson D. D. 
Published: August 2021

AbstractWe investigated all the pairs of Mw ≥ 7.5 shallow earthquakes in the Harvard catalog that occurred at a centroid distance of less than 100 km. We showed that most of these pairs have similar focal mechanisms. Because these earthquakes generally should have focal regions in excess of 100 km diameter, their rupture zones apparently intersect. For all these pairs, the time interval is significantly less than the time span needed for plate motion to accumulate the strain released by the first event. These observations conflict strongly with quasi-periodic recurrence models on which the seismic gap hypothesis is based. Power-law recurrence fits these earthquake observations much better.
An improvement on the estimation of pseudoresponse spectral velocity using RVT method
Authors: Liu L. , Pezeshk S. 
Published: August 2021

AbstractThe basic assumption in the prediction of peak ground acceleration (PGA), peak ground velocity (PGV), and pseudoresponse spectral values by the random vibration theory (RVT) method is that the ground motion process is a bandlimited Gaussian random process (BGRP). However, for the estimation of pseudoresponse spectral values, the process is the output of a single-degree-of-freedom (SDOF) system subjected to the input of a BGRP. The output process is a narrow-band random process because a SDOF system acts as a narrow-bandpass filter. The property of a narrow-band process is significantly different from that of a bandlimited process. There is an obvious difference in the estimations of the pseudoresponse spectral values based on bandlimited or narrow-band process, especially in the lower frequency part. In this study, we propose an empirical method to improve the estimation of the pseudoresponse spectral values by the RVT based on the consideration of properties of a narrow-band Gaussian stationary process. Comparisons of our results with those of previous research studies and the time domain simulation (TDS) shows that our empirical approach improves the estimation of pseudoresponse spectral values in the long period range.
Focal mechanism determination and identification of the fault plane of earthquakes using only one or two near-source seismic recordings
Authors: Delouis Bertrand , Legrand Denis 
Published: August 2021

AbstractA waveform inversion scheme was developed in order to explore the resolving power of one or two seismic recordings at short epicentral distance for the determination of focal mechanisms and the identification of the fault plane of earthquakes. Two key features are used to constrain the fault parameters with a reduced number of stations: (1) a simple finite-dimension source model and (2) the modeling of the complete displacement field, including the near-field waves. The identification of the fault plane should be possible, even with a single station, as soon as the seismograms produced by the two nodal planes of a same focal mechanism are significantly different, which is the general case when waveforms are controlled by source finiteness. Seven parameters, including the strike, dip, rake, and dislocation, are explored with a grid search, and the minima of the misfit error between the observed and calculated seismograms are mapped. With such an approach, it is possible to conclude about the uniqueness or nonuniqueness of the solutions. The method is tested with three earthquakes of moderate to large size for which the fault plane is well established and for which strong-motion records are available at maximum distances of a few tens of kilometers. Test events are the 1994 Northridge (Mw = 6.7, California), the 1996 Copala (Mw = 7.3, Mexico), and the 1996 Pinotepa Nacional (Mw = 5.4, Mexico) earthquakes. In the case of inversions with two stations, we find a unique solution, or a group of similar solutions, with a good estimation of the focal mechanism and the proper selection of the fault plane. Our results also show that in some cases a single station may be enough to recover the fault parameters. The inversion scheme presented here may be systematically applied to future earthquakes, especially to those recorded by few stations. It should be particularly useful in the case of blind faults for which the fault plane may not be identified with the help of other data.
The Evaluation of Dual-Task Activities and Balance in Older adults During the COVID-19 Pandemic: A Pilot Study
Authors: SERTEL Meral , ABİT KOCAMAN Ayşe , AYDOĞAN ARSLAN Saniye , UĞURLU Kübra 
Published: August 2021

AIM: The aim of this study is to evaluate the dual-task activities and balance of older adults during the COVID-19 pandemic.
MATERIAL AND METHOD: This study was conducted between August 2020 and November 2020 and included older adults who lived in a house environment in Ankara, met the study criteria, volunteered to participate in the study, and were aged between 65-80 years. The sociodemographic information of the older adults was recorded. The balance and dual-task performances of the individuals were assessed by the Tinetti Balance and Gait Test, Timed Up and Go Test (TUG), and Dual-Task Questionnaire (DTQ), and their cognitive states were evaluated by the Mini-Mental State Test. The individuals were requested to perform the tests by transferring an object from one hand to the other as an additional motor task and by counting two by two as an additional cognitive task.
RESULTS: The mean age of the individuals was 70.35±5.44 years. According to Spearman’s correlation analysis, a moderate-level correlation was identified between the DTQ and the Tinetti Balance and Mobility Scale and its subgroups, and a low-level correlation was observed between the DTQ and TUGMotor (p˂0.005). No correlation was detected between the DTQ and TUGCognitive. In terms of sex, TUGCognitive was found to be longer in male individuals.
CONCLUSION: It has been demonstrated that there is a correlation between the DTQ and balance and functional states.
LEADERSHIP POTENTIAL OF CIVIL SERVANTS IN THE VOCATIONAL TRAINING PROCESS
Authors: Vorobieva Evgeniya , Lohosh Khrystyna 
Published: August 2021

The features of development of leader qualities of future civil servants are reflected and those, who is in government service in the process of professional preparation at higher school and by in-plant training. Also in the article certainly, that the input of the renewed maintenance and forms of professional preparation of future civil servants in HEIs and input of training forms in the process of in-plant training assists to development of their leader potential, actualized interest in practical activity in government service that assists further activity in a permanent capture by knowledge and use of them in practice in administrative activity of government service.
The article contains authorial interpretation of directions of development of leader potential of civil servants as within the framework of the special programs of preparation so in the process of professional preparation in HEIs.