bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of Q in eastern Canada using coda waves
Authors: Woodgold Catherine R. D. 
Published: September 2021

Abstract
The determination of Q0 and η (where Q = Q0fη) from seismic coda over the United States by Singh and Herrmann (1983) has been extended to cover a large area of southeastern Canada (south of 50°N, east of 80°W). The model used assumes, like that of Singh and Herrmann (1983), that the coda is generated by isotropic single scattering of surface waves, but also takes into account nonzero source-receiver distances. An average value of 0.43 is found for η for the whole region. Assuming this value of η, and using data in the 1 to 10 Hz range, Q0 has been estimated independently in nine different subregions, so that the variation of Q0 within the area of study can be seen. Q0 varies from 480 in New Brunswick to 770 near Ottawa. Q0 is also high (760) in the Adirondack Mountains and near Val-d'Or, Quebec (730), but lower along the St. Lawrence River (620). The results agree well with those of other studies in which Q for the same geographical regions is determined by other methods.
Above 10 Hz and below 1 Hz, Q is more strongly dependent on frequency than in the 1 to 10 Hz range. The same result has been obtained by Shin and Herrmann (1987) by a different method.
Source characteristics of earthquakes along the southern San Jacinto and Imperial fault zones (1937 to 1954)
Authors: Doser Diane I. 
Published: September 2021

Abstract
Body waveform inversion techniques are used to study the source parameters of four earthquakes occurring between 1937 and 1954 along the southern San Jacinto and Imperial faults (1937 Buck Ridge, 1940 Imperial Valley, 1942 Borrego Mountain, and 1954 Salada Wash events). All earthquakes had simple rupture histories with the exception of the 1940 Imperial Valley main shock, which consisted of at least four subevents whose relative locations indicate unilateral rupture toward the southeast. Earthquakes in regions of high heat flow (&gt;80 mW/m2) had focal depths near the base of the seismogenic zone (8 to 10 km). The 1937 Buck Ridge earthquake, located in a region of lower heat flow, however, appears to have occurred at a shallow (3 ± 2 km) depth. The location, mechanism, and aftershock distribution for the 1942 Borrego Mountain earthquake suggest it could have occurred along the Split Mountain fault, a recently identified northeast-trending cross fault located between the Elsinore and Coyote Creek faults or along an unnamed fault that parallels the trend of the Coyote Creek fault. Moment and rupture length estimates obtained from this study agree well with estimates obtained in previous studies that used different data sets.
Effects of centroid location on determination of earthquake mechanisms using long-period surface waves
Authors: Zhang Jiajun , Lay Thorne 
Published: September 2021

AbstractDetermination of shallow earthquake source mechanisms by inversion of long-period (150 to 300 sec) Rayleigh waves requires epicentral locations with greater accuracy than that provided by routine source locations of the National Earthquake Information Center (NEIC) and International Seismological Centre (ISC). The effects of epicentral mislocation on such inversions are examined using synthetic calculations as well as actual data for three large Mexican earthquakes. For Rayleigh waves of 150-sec period, an epicentral mislocation of 30 km introduces observed source spectra phase errors of 0.6 radian for stations at opposing azimuths along the source mislocation vector. This is larger than the 0.5-radian azimuthal variation of the phase spectra at the same period for a thrust fault with 15° dip and 24-km depth. The typical landward mislocation of routinely determined epicenters of shallow subduction zone earthquakes causes source moment tensor inversions of long-period Rayleigh waves to predict larger fault dip than indicated by teleseismic P-wave first-motion data. For dip-slip earthquakes, inversions of long-period Rayleigh waves that use an erroneous source location in the down-dip or along-strike directions of a nodal plane, overestimate the strike, dip, and slip of that nodal plane. Inversions of strike-slip earthquakes that utilize an erroneous location along the strike of a nodal plane overestimate the slip of that nodal plane, causing the second nodal plane to dip incorrectly in the direction opposite to the mislocation vector. The effects of epicentral mislocation for earthquakes with 45° dip-slip fault mechanisms are more severe than for events with other fault mechanisms. Existing earth model propagation corrections do not appear to be sufficiently accurate to routinely determine the optimal surface-wave source location without constraints from body-wave information, unless extensive direct path (R1) data are available or empirical path calibrations are performed. However, independent surface-wave and body-wave solutions can be remarkably consistent when the effects of epicentral mislocation are accounted for. This will allow simultaneous unconstrained body-wave and surface-wave inversions to be performed despite the well known difficulties of extracting the complete moment tensor of shallow sources from fundamental modes.
Fast and accurate dynamic raytracing in heterogeneous media
Authors: Lafond Claude F. , Levander Alan R. 
Published: September 2021

Abstract
We have developed a fast and accurate dynamic raytracing method for 2.5-D heterogeneous media based on the kinematic algorithm proposed by Langan et al. (1985). This algorithm divides the model into cells of constant slowness gradient, and the positions, directions, and travel times of the rays are expressed as polynomials of the travel path length, accurate to the second other in the gradient. This method is efficient because of the use of simple polynomials at each raytracing step.
We derived similar polynomial expressions for the dynamic raytracing quantities by integrating the raytracing system and expanding the solutions to the second order in the gradient. This new algorithm efficiently computes the geometrical spreading, amplitude, and wavefront curvature on individual rays. The two-point raytracing problem is solved by the shooting method using the geometrical spreading. Paraxial corrections based on the wavefront curvature improve the accuracy of the travel time and amplitude at a given receiver.
The computational results for two simple velocity models are compared with those obtained with the SEIS83 seismic modeling package (Cerveny and Psencik, 1984); this new method is accurate for both travel times and amplitudes while being significantly faster. We present a complex velocity model that shows that the algorithm allows for realistic models and easily computes rays in structures that pose difficulties for conventional methods. The method can be extended to raytracing in 3-D heterogeneous media and can be used as a support for a Gaussian beam algorithm. It is also suitable for computing the Green's function and imaging condition needed for prestack depth migration.
A statistical model for ground motion produced by earthquakes at local and regional distances
Authors: Ou Gwo-Bin , Herrmann Robert B. 
Published: September 2021

AbstractTo adapt random process theory techniques for statistical estimation of peak ground motion to more realistic earth models, we constrain the parameters of duration, geometrical spreading, and spectral shape by modeling the main ground motion as being the result of major contributions by the direct S wave and supercritically reflected S waves. The results of our modeling are constrained to be consistent with values from full-wave synthetics for the test models. The combination of estimation theory and theoretical amplitude spectrum of the main ground motion within the ergodic window successfully predicts the mean peak vertical ground displacements, velocities, and accelerations of the 1982 Miramichi earthquakes in New Brunswick, Canada. In addition, upon considering the effects of source depth and crustal structure for the November 25, 1988, Saguenay earthquake (M = 5.8) in Québec, Canada, the predicted mean peak horizontal ground accelerations match the observed data very well. The effects of source depth and crustal structure on the peak ground motion are complicated for different source sizes and at different epicentral distance ranges.
Array analysis of seismic scattering
Authors: Dainty Anton M. , Nafi Toksöz M. 
Published: September 2021

Abstract
The use of high frequency arrays permits investigation of the spatial as well as the temporal character of the seismic wavefield in the frequency band 1-10 Hz. The authors have carried out investigations into seismic scattering at NORESS, FINESA, and ARCESS. Two principal methods have been used, frequency-wavenumber analysis of coda and coherency analysis of seismic phases. For regional seismograms, frequency-wavenumber analysis of Lg coda shows that Lg-to-Lg scattering dominates and that scattering is initially concentrated in the forward direction, changing to isotropic backscatter later in the coda. The P coda is more complex, although all cases studied show that energy is concentrated in the on-azimuth direction. However, different phase velocities are found for the three different cases studied, indicating that P coda is made up of several different contributions whose balance varies in different situations. In previous work, we have found that the decay of coherency with spatial separation scales as the wavelength for the Lg phase of regional events in the frequency band 1-10 Hz, declining to about 0.5 within one wavelength. Analysis of synthetic seismograms for realistic models of the area suggests that this loss of coherency is not due to dispersion, reaffirming a scattering interpretation. However, the decline in coherency is isotropic, seemingly contradicting the finding of forward scattering found in the frequency-wavenumber analysis. This may reflect a sensitivity of the coherency analysis to scattering within or very close to the array, while the frequency-wavenumber analysis favors scatterers at greater distance.
Discriminating quarry blasts from earthquakes using coda waves
Authors: Su F. , Aki K. , Biswas N. N. 
Published: September 2021

AbstractA new quarry blast-earthquake discrimination method is presented based on the analysis of seismic coda waves. Quarry blasts and local earthquakes in the area encompassing the south-central Mojave Desert and Eastern Transverse Ranges were used to test this method. We found that the coda decay rate Qc−1 is significantly higher for quarry blasts than earthquakes for lower frequencies (1.5 and 3 Hz) for lapse time up to about 30 sec. This result is attributed to the greater contribution of surface waves to quarry blasts due to the shallowness of their source depth. The difference in Qc−1, however, disappears for lapse time greater than 30 sec for the same frequency range as well as for higher frequencies (6 and 12 Hz) for lapse time greater than 20 sec. This suggests that the coda waves, at the lapse time greater than these critical values, are dominated by the same type of body waves, probably S waves, for both quarry blasts and earthquakes. The power spectrum P0(ω) obtained after the correction for attenuation was compared between earthquakes and quarry blasts at the same stations, and a significant difference was found in the spectral shape between these two data sets. The curves of power spectrum P0(ω) versus frequency for quarry blasts decrease more sharply than for earthquakes at high frequencies, indicating a lack of energy in high frequencies for quarry blasts as compared to earthquakes. The different frequency dependence of power spectrum P0(ω) between quarry blasts and earthquakes is attributed to their different source properties and can be used for seismic discrimination of quarry blasts from earthquakes.
PANDA: A simple, portable seismic array for local- to regional-scale seismic experiments
Authors: Chiu J. M. , Steiner G. , Smalley R. , Johnston A. C. 
Published: September 2021

Abstract
A portable array for numerical data acquisition (PANDA) was designed and built in-house at the Center for Earthquake Research and Information (CERI), Memphis State University. The design goal was a transportable set of instruments that could record high-quality seismic data. By making modifications to traditional seismic network technology and using a super-microcomputer workstation for digital data acquisition, this array provides a set of reliable and cost-effective instruments for the collection and analysis of high-resolution seismic data. The field equipment and central recording system are designed to overcome several major limitations in existing seismic network technologies, such as low dynamic range, single-component recording, lack of a common time base between stations, topographic constraints in radio telemetry, and lack of field processing capabilities. PANDA overcomes these limitations. To increase the dynamic range and record full three-component data, each PANDA station has six channels divided into two three-component sets. One set is operated at high gain and the other at low gain, giving a minimum of 90 dB dynamic range. Modular design of the PANDA station electronics facilitates field maintenance and also permits the stations to be run in several additional modes (e.g., with both sets of three channels operating at high gain) or with different sensors on each set. Each telemetry link to the central recording site carries data from two stations (12 channels) by repeating data from an “outer” seismic station through an “inner” seismic station and repeater combination. In addition, several repeat-only stations were built. This ability to repeat signals increases the aperture of PANDA to more than 150 km and overcomes topographic limitations on station locations. Other design features include low power consumption, solar power operation, and transmission of daily calibration and diagnostic signals. These features enable the stations to operate unattended for long periods and provide verification of station performance from the central recording site. The central recording system is based on a high-performance super-micro-computer workstation with a 256 channel A/D front end, which allows both real time digital recording with a common time base and immediate processing of the data. A 40-station network with 6 channels per station uses 240 channels, leaving 16 channels for auxiliary inputs such as time codes and spares. PANDA was field tested in the Arkansas earthquake swarm region from October 1986 to April 1987. It was then deployed in San Juan, Argentina, from August 1987 to May 1988, and in Jujuy, Argentina, from September 1988 to May 1989. A total of more than 20,000 earthquakes were recorded during the two Argentina experiments.
Loma Prieta aftershock relocation withS-Ptravel times: Effects of 3-D structure and true error estimates
Authors: Schwartz Susan Y. , Nelson Glenn D. 
Published: September 2021

AbstractAftershocks of the 18 October 1989 Loma Prieta, California, earthquake are located using S-P arrival-time measurements from stations of the PASSCAL aftershock deployment. We demonstrate the effectiveness of using S-P arrival-time data in locating earthquakes recorded by a sparse three-component network. Events are located using the program QUAKE3D (Nelson and Vidale, 1990) with both 2-D and 3-D velocity models that have been developed independently for this region. The dense coverage of the area around the Loma Prieta rupture zone by instruments of the California Network (CALNET) has allowed the U.S. Geological Survey (USGS) to find P-wave earthquake locations for both velocity models, which we compare with our solutions. We also perform synthetic calculations to estimate realistic location errors resulting from uncertainties in both the 3-D velocity structure and the timing of arrivals. These calculations provide a comparison of location accuracies obtained using S-P arrival times, S and P arrival times, and P times alone. We estimate average absolute errors in epicentral location and in depth for the Loma Prieta aftershocks to be just under 2 km and 1 km, respectively, using S-P phase data and the sparse PASSCAL instrument coverage. The synthetic tests show that these errors are much smaller than those predicted using P-wave data alone and are nearly the same as those predicted using S- and P-phase data separately. This suggests that future aftershock recording deployments with sparse networks of three-component data can retrieve accurate event locations even if absolute timing is problematic.We find moderate differences between our locations and those determined by the USGS from a larger network of stations; however, common characteristics in both seismicity patterns are apparent. Neither set of locations yields earthquake patterns that can be easily interpreted in terms of simple faulting geometries. The absence of a simple pattern in both sets of earthquake locations indicates that this complexity is not the result of earthquake mislocation but is a genuine feature of the seismicity. A deep southwesterly dipping plane and a near-vertical fault extending from the surface to at least 7-km depth beneath the surface trace of the San Andreas Fault are imaged by both sets of earthquake locations. Although earthquake locations indicate the existence of many more fault segments, the complexity of this region requires that a definitive picture of the faulting geometry will have to await improvement in our knowledge of the P- and S-wave velocity structures.
The site response of two rock and soil station pairs to strong and weak ground motion
Authors: Darragh Robert B. , Shakal Anthony F. 
Published: September 2021

Abstract
The site response to strong and weak ground motion depends largely on the subsurface conditions at the soil site for the two rock-soil station pairs studied. The first station pair consists of a soft-soil site (Treasure Island) and a sandstone and shale site (Yerba Buena Island). These stations recorded strong ground shaking from the Loma Prieta mainshock and weak ground motion from four aftershocks. The range of peak ground acceleration is from approximately 0.00006 to 0.07 g at the rock site. Compared to the rock site, the strong ground motion at the soft-soil site is amplified by a factor of about 3 over a frequency range from 0.5 to 2.0 Hz. The amplification is much higher for weak motion and suggests a dependence on signal amplitude. For example, near 1 Hz, the site response shows an increasing amplification as magnitude (and the peak velocity at the rock site) decreases. For events of local magnitude 7.0, 4.3, 4.1, 3.5, and 3.3, the maximum soil-site amplifications are 4, 12, 17, 19, and 25, respectively.
A second station pair consisting of a stiff-soil site (Gilroy #2) and a sandstone site (Gilroy #1) was also studied with contrasting results. These two stations recorded strong ground shaking from the 1979 Coyote Lake, 1984 Morgan Hill, and 1989 Loma Prieta mainshocks. Weak ground motion was recorded at these stations after the Loma Prieta mainshock. The range of peak ground acceleration is from 0.006 to 0.43 g at the rock site. Unlike the results for the soft-soil study above, the estimated stiff-soil site responses are not significantly different for strong and weak motion from 0.5 to 2.0 Hz. Near 0.7 Hz, the stiff-soil site responses range from 2.5 to 4.5 for strong ground shaking from three mainshocks and from 1.5 to 4.0 for weak ground shaking from thirteen aftershocks.
State response to the Loma Prieta earthquake: Competing against time
Authors: Thiel Charles C. , Housner George W. , Tobin L. Thomas 
Published: September 2021

Abstract
A Board of Inquiry was appointed by the Governor of California to investigate the damage, particularly to bridges and freeway structures, caused by the 1989 Loma Prieta earthquake. The Governor wanted to know not only what happened, but how to prevent such destruction in the future. The Board identified three essential challenges that must be addressed by the citizens of California, if they expect a future adequately safe from earthquakes: (1) ensure that earthquake risks posed by new construction are acceptable; (2) identify and correct unacceptable seismic safety conditions in existing structures; and (3) develop and implement actions that foster the rapid, effective, and economic response to and recovery from damaging earthquakes. The Governor issued an Executive Order implementing the principal Board recommendations that all state-owned and -operated structures are to be seismically safe and that important structures are to maintain their function after earthquakes. The Seismic Safety Commission has evaluated the response of state agencies to the Order and found performance generally to be good, but variable. Inadequate funding is the most serious and the most difficult for the agencies to address internally, as are legislative capital budgeting processes that are cumbersome. Agencies were encouraged to identify single administrators responsible for seismic safety to assure management accountability, rather than the generally diffuse responsibility found in most agencies. The Board, Governor, and Commission all concluded that, while much progress has been made during the past two decades in reducing earthquake risks, much more awaits doing. More aggressive efforts to mitigate the consequences of future, certain earthquakes are needed if one of the most fundamental of responsibilities of government is to be fulfilled—to provide for the public safety.
Faculty in the Applied and Pure Sciences May Have Limited Experience with E-books
Authors: Kaari Jennifer 
Published: September 2021

A Review of:
Bierman, J., Ortega, L., & Rupp-Serrano, K. (2010). E-book usage in pure and applied sciences. Science & technology libraries, 29(1-2), 69-91. https://doi.org/10.1080/01942620903579393
Abstract
Objective – To determine the usage of and attitudes toward e-books among faculty in the applied and pure sciences.
Design – Online survey and in-person interviews.
Setting – A large public university in the United States.
Subjects – 11 faculty members.
Methods – Participants completed an 11-item survey covering demographic data and questions about electronic book experience and preferences. This was followed up by an in-person interview with the researchers. The interviews were structured into three sections: opening questions about e-book usage, an interactive demonstration and discussion of two preselected e-books, and final follow-up questions. Interviews followed a general script of prepared questions, but also encouraged open discussion and dialogue.
Main Results – Most participants in the study reported limited experience with e-books and only 3 of the 11 participants reported using library-purchased e-books in their research and instruction. Participants noted ease of access and searchability as key advantages of e-books. Concerns included the belief that reading and learning is more difficult on a desktop computer, as well as concerns about the stability and reliability of e-book access. Participants also felt negatively about the necessity to create a new login profile and password to access e-books. The study found no difference in the way faculty in pure and applied sciences approached e-books.
Conclusion – The authors determine that e-books will likely become more commonly used in academia. Users want e-books that are easy to use and customizable. In addition, the authors conclude that librarians need to understand their patrons’ needs as e-book users and proactively promote and market their e-book collections.