bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship of the kickapoo fault to the Johnson Valley and Homestead Valley faults, San Bernardino County, California
Authors: Sowers J. M. , Unruh J. R. , Lettis W. R. , Rubin T. D. 
Published: September 2021

AbstractThe 1992 Mw 7.3 Landers earthquake rupture propagated from the Johnson Valley fault to the Homestead Valley fault across Homestead Valley. Rupture was concentrated along the Kickapoo fault (a.k.a, Landers fault), a previously unrecognized north-south-striking, 5-km-long fault in Homestead Valley, and along small secondary fault traces east of the Kickapoo fault. To better understand the role of the Kickapoo fault in accommodating slip between the Johnson Valley fault and the Homestead Valley fault, we performed detailed aerial photograph interpretation and field mapping of alluvial deposits, geomorphology, and co-seismic surface rupture; evaluated existing water-well data; and conducted a gravity survey of the Homestead Valley area. These data show that the Kickapoo fault is a pre-1992 structure best interpreted as the northward continuation of the southern Johnson Valley fault. The Kickapoo fault merges northward with the northwest-striking Homestead Valley fault. Thus, we interpret that the Johnson Valley, Kickapoo, and Homestead Valley faults form an interlinked system. Large ruptures similar to the 1992 Landers rupture may have repeatedly propagated between the Johnson Valley and Homestead Valley faults along the Kickapoo fault. The Kickapoo-Johnson Valley fault intersection defines a 1-km-wide, left-restraining bend. Uplifted alluvial deposits and pressure ridges are common within the bend, indicating the bend is a long-lived contractional feature. Homestead Valley itself is underlain by relatively thin alluvial deposits over crystalline bedrock, showing that no significant subsidence has occurred during the late Quaternary. These observations are consistent with the accommodation of north-south right shear on the southern Johnson Valley and Kickapoo faults in Homestead Valley.
The co-seismic slip distribution of the Landers earthquake
Authors: Freymueller J. , King N. E. , Segall P. 
Published: September 2021

AbstractWe derived a model for the co-seismic slip distribution on the faults which ruptured during the Landers earthquake sequence of 28 June 1992. The model is based on the inversion of surface geodetic measurements, primarily vector displacements measured using the Global Positioning System (GPS). The inversion procedure assumes that the slip distribution is to some extent smooth and purely right-lateral strike slip. For a given fault geometry, a family of solutions of varying smoothness can be generated.We choose the optimal model from this family based on cross-validation, which measures the predictive power of the data, and the trade-off of misfit and roughness. Solutions which give roughly equal weight to misfit and smoothness are preferred and have certain features in common: (1) there are two main patches of slip, on the Johnson Valley fault, and on the Homestead Valley, Emerson, and Camp Rock faults; (2) virtually all slip is in the upper 10 to 12 km; and (3) the model reproduces the general features of the geologically measured surface displacements, without prior constraints on the surface slip. In all models, regardless of smoothing, very little slip is required on the fault that represents the Big Bear event, and the total moment of the Landers event is 9 · 1019 N-m. The nearly simultaneous rupture of multiple distinct faults suggests that much of the crust in this region must have been close to failure prior to the earthquake.
Postseismic deformation following the Landers earthquake, California, 28 June 1992
Authors: Shen Zheng-Kang , Jackson David D. , Feng Yanjie , Cline Michael , Kim Mercedes , Fang Peng , Bock Yehuda 
Published: September 2021

AbstractAccelerated strain followed the Landers and Big Bear earthquakes, returning to the normal rate only after a period of several months. We observed this strain throughout most of southern California using the Global Positioning System (GPS). Three GPS receivers operating continuously in fixed positions at Pinyon Flat, Jet Propulsion Laboratory (Pasadena), and Goldstone all recorded postseismic deformation in a relative sense. In addition, we established 16 sites where we deployed portable receivers occasionally over a period of about 6 months near the rupture zones of the earthquakes. Anomalous postseismic displacements ranged from 55 mm near the epicenter to a few millimeters far from the fault. We modeled the displacements, using dislocation theory, as due to variable slip on the faults that were displaced at the times of the earthquakes. The model suggests that the postseismic strain released the equivalent of about 15% of the seismic moment of the mainshock. While the strain released from the upper 10 km is about the same as what can be explained by direct effects of aftershocks, the major contribution of strain release comes from the lower layer, below 10-km depth. Significant afterslip or viscous relaxation must have occurred below 10-km depth to explain the observed deformation more than 100 km from the fault. One interpretation is that high stress on the margin of the co-seismic rupture zone drives the rupture to extend itself into urbroken rock below and along the initial rupture zone.
Dynamic growth of mixed-mode shear cracks
Authors: Andrews D. J. 
Published: September 2021

AbstractA pure mode II (in-plane) shear crack cannot propagate spontaneously at a speed between the Rayleigh and S-wave speeds, but a three-dimensional (3D) or two-dimensional (2D) mixed-mode shear crack can propagate in this range, being driven by the mode III (antiplane) component. Two different analytic solutions have been proposed for the mode II component in this case. The first is the solution valid for crack speed less than the Rayleigh speed. When applied above the Rayleigh speed, it predicts a negative stress intensity factor, which implies that energy is generated at the crack tip. Burridge proposed a second solution, which is continuous at the crack tip, but has a singularity in slip velocity at the Rayleigh wave. Spontaneous propagation of a mixed-mode rupture has been calculated with a slip-weakening friction law, in which the slip velocity vector is colinear with the total traction vector. Spontaneous trans-Rayleigh rupture speed has been found. The solution depends on the absolute stress level. The solution for the in-plane component appears to be a superposition of smeared-out versions of the two analytic solutions. The proportion of the first solution increases with increasing absolute stress. The amplitude of the negative in-plane traction pulse is less than the absolute final sliding traction, so that total in-plane traction does not reverse. The azimuth of the slip velocity vector varies rapidly between the onset of slip and the arrival of the Rayleigh wave. The variation is larger at smaller absolute stress.
Ground-motion amplitude across ridges
Authors: Pedersen H. , Le Brun B. , Hatzfeld D. , Campillo M. , Bard P.-Y. 
Published: September 2021

AbstractLocal amplification and wave diffraction on an elongated ridge near Sourpi in central Greece were studied by the analysis of seismic records of local and regional earthquakes. Data were obtained during field work especially designed for this purpose. These data were analyzed in the frequency and time domains. In the frequency domain, spectral ratios show amplifications of 1.5 to 3 at the ridge top relative to the base of the ridge. The horizontal components of motion are more amplified than the vertical component and the observed spectral ratios seem stable for different earthquake locations. Theoretical spectral ratios, calculated by the indirect boundary element method, are dependent on earthquake location but are in general agreement with the observed spectral ratios. Another dataset, from Mont St. Eynard in the French Alps, showed similar characteristics with spectral amplitudes on the top of the ridge up to four times those on the flank. These relative amplifications are within the range predicted by numerical simulations. The numerical simulations also show that the topographic effect involves the emission of diffracted waves propagating from the top toward the base of the ridge. The use of a seven-station array on the ridge at Sourpi made it possible to identify such waves. The analysis was performed with wave separation methods using singular value decomposition and spectral matrix filtering. Our results show agreement between experimental data and theoretical results supporting the use of numerical simulations for estimation of purely topography-induced amplification on ridge tops. Our results also show that such amplification is moderate for the ridges under study.
Bootstrapping shear-wave splitting errors
Authors: Sandvol Eric , Hearn Thomas 
Published: September 2021

Abstract
We have developed a bootstrap method to estimate errors associated with inverting SKS waveforms for shear-wave splitting parameters. Although presented for shear-wave splitting inversions, this method is suitable for any waveform inversion procedure. The bootstrap error estimation method consists of multiple inversions of simulated data that imitate the original data with differing noise sequences. The results of the bootstrap inversions are used to directly calculate variances and covariances for all model parameters. We employ a bootstrap error estimation technique to nonlinear inversion for shear-wave splitting parameters. Since seismic data have correlated errors, the bootstrap method was modified for stationary bandlimited time series. This modified bootstrap method was applied to shear-wave splitting measurements from over 60 pairs of horizontal seismograms. The method is stable under a large range of noise conditions. By using this bootstrap method, we can distinguish among data with no apparent splitting, data with splitting, and noisy data.
Strain accumulation in Owens Valley, California, 1974 to 1988
Authors: Savage J. C. , Lisowski M. 
Published: September 2021

Abstract
Strain accumulation observed over the 1974 to 1988 interval in a 25 by 100 km aperture trilateration network spanning Owens Valley is adequately described by a strain rate that is uniform in space and time. The tensor strain-rate components referred to a coordinate system with the 2 axis directed N18°W (parallel to the trend of the valley) and the 1 axis N72°E are ∈˙11′ = 0.042 ± 0.014 μstrain/yr, ∈˙12′ = -0.058 ± 0.007 μstrain/yr, and ∈˙22′ = 0.002 ± 0.014 μstrain/yr; quoted uncertainties are standard deviations and extension is reckoned positive. Across the 25-km breadth of the network, this amounts to 1.0 ± 0.3 mm/yr extension normal to the axis of the valley, 2.9 ± 0.4 mm/yr right-lateral shear across the axis, and no extension parallel to the axis. If the measured strain accumulation is attributed to slip on the deeper section of the Owens Valley fault with the uppermost 10 km of the fault locked, the observed right-lateral deformation would imply about 7 mm/yr right-lateral slip on the buried fault, much greater than the geologic estimate of 2 ± 0.5 mm/yr right-lateral secular slip (Beanland and Clark, 1994). Nor is the observed uplift profile across the valley consistent with continuing normal slip on just the deep segment of the Owens Valley fault; normal slip at depth on the Sierra frontal fault also seems to be required. The observed deformation across Owens Valley apparently implies processes more complicated than those represented by the conventional model of strain accumulation along a throughgoing fault.
Constraints on temporal variations in velocity near Anza, California, from analysis of similar event pairs
Authors: Haase Jennifer S. , Shearer Peter M. , Aster Rick C. 
Published: September 2021

AbstractSimilar earthquake pairs recorded by the Anza Seismic Network in southern California are used as repeatable sources to place an upper limit on temporal changes in seismic velocity which occurred in the vicinity of the Anza seismic gap in the last 9 yr. Relative arrival times for each pair of events are found using a cross-correlation method and relative locations are calculated to verify that the pairs have nearly identical hypocenters. The time separation between events in these pairs varies from less than a day to almost 7 yr. The long-term changes in seismic travel times, as measured from the pairs with the longest time separation, are not significantly greater than the noise level estimated from the short-time-separation event pairs. Almost all P-wave paths show less than 0.06% (0.007 sec) change in travel time and all S-wave paths have less than 0.03% (0.004 sec) change. Sensitivity tests place an upper bound on travel-time changes that could be compensated by hypocenter mislocation at 0.2%. There is no evidence that localized stress accumulation causes measurable changes in seismic velocity in the Anza region.
Comment on “microearthquake location: a nonlinear approach that makes use of a Simplex stepping procedure” by A. Prugger and D. Gendzwill
Authors: Ge M. 
Published: September 2021

Abstract
This work discusses the concept and mathematical procedure of error estimation for the Simplex source location method. The precise formulas for the calculation of station residuals are derived for the absolute value method (L1 norm) and the least-squares method (L2 norm). Two other related problems, origin time and ill-conditioned matrices, are also discussed.
Simulation of 3D elastic wave propagation in the Salt Lake Basin
Authors: Olsen Kim B. , Pechmann James C. , Schuster Gerard T. 
Published: September 2021

AbstractWe have used a 3D finite-difference method to model 0.2 to 1.2 Hz elastodynamic site amplification in the Salt Lake Valley, Utah. The valley is underlain by a sedimentary basin, which in our model has dimensions of 48 by 25 by 1.3 km. Simulations are carried out for a P wave propagating vertically from below and for P waves propagating horizontally to the north, south, east, and west in a two-layer model consisting of semi-consolidated sediments surrounded by bedrock.Results show that in general, sites with the largest particle velocities, cumulative kinetic energies, duration times of motion, and spectral magnitudes overlie the deepest parts of the basin. The maximum values of these parameters are generally found above steeply dipping parts of the basin walls. The largest vector particle velocities are associated with P or SV waves that come from within 10° of the source azimuth. Low-energy S and surface waves follow the strongest arrivals. The largest peak particle velocities, cumulative kinetic energies, signal durations, and spectral magnitudes in the simulations are, respectively, 2.9, 15.9, 40.0, and 3.5 times greater than the values at a rock site measured on the component parallel to the propagation direction of the incident P wave. Scattering and/or mode conversions at the basin boundaries contribute significantly to the signal duration times.As a check on the validity of our simulations, we compared our 3D synthetic seismograms for the vertically incident plane P wave to seismograms of nearly vertically incident teleseismic P waves recorded at an alluvium site in the valley and at a nearby rock site. The 3D synthetics for the alluvium site overestimate the relatively small amplification of the initial P wave and underestimate the large amplification of the coda. Using 2D simulations, we find that most of the discrepancies between the 3D synthetic and observed records can be explained by an apparently incorrect total sediment thickness, omission from the model of the near-surface low-velocity unconsolidated sediments and of attenuation, and the inexact modeling of the incidence angle of the teleseism. The records from a 2D simulation in which these deficiencies are remedied (with Q = 65), and which also includes topography and a near-surface velocity gradient in the bedrock, provide a better match to the teleseismic data than the records from the simple two-layer 3D simulation.Our results suggest that for steeply incident P waves, the impedance decrease and resonance effects associated with the deeper basin structure control the amplification of the initial P-wave arrival, whereas reverberations in the near-surface unconsolidated sediments generate the large-amplitude coda. These reverberations are caused mainly by P-to-S converted waves, and their strength is therefore highly sensitive to the incidence angle of the source.
Site-dependent attenuation relations of seismic motion parameters at depth using borehole data
Authors: Fukushima Yoshimitsu , Gariel Jean-Christophe , Tanaka Ryozo 
Published: September 2021

Abstract
Using more than 500 accelerometric records from three vertical arrays located in Japan, we performed a regression analysis in order to derive attenuation relationships at underground sites with depths ranging from 100 to 950 m. Analyses were conducted on both peak ground acceleration and pseudo-velocity response spectra. Because of a positive correlation between magnitude and distance, a two-step regression technique was employed. Results show that, compared with surface ground motion, peak accelerations at underground sites are lower by a factor ranging from 1.5 to 4 according to the depth. In the case of response spectra, differences between ground surface and underground spectra are dependent on geological conditions. For the three sites considered in the study, underground pseudo-velocity response spectra show amplitudes lower by a factor ranging from 1.5 to 10 according to the depth or the period considered.
Ratios between the receiver responses obtained at different depths provided average transfer functions. Those were compared with transfer functions calculated by averaging ratios of observed response spectra between different depths. A good agreement between the two techniques was found. Finally, theoretical transfer functions were estimated using both one-dimensional SH and complete wave modeling. It was shown that the characteristics of the incident wave field can play an important role in the estimation of theoretical transfer functions.
Histopathological evaluation of Endometrium hyperplasia and it’s correlation with the clinical parameters in a tertiary care hospital
Authors: Rai Tina , Uniya Upasana , Shrivastava Archana , Rai G.S 
Published: September 2021

: Abnormal uterine bleeding is a common clinical presentation in the perimenopausal age group its biopsy serves as an excellent clue to the underlying disease. The presentation may vary according to the type of endometrial hyperplasia and their correlation helps in the proper management of the patients complain.: To analyze the histopathological patterns of endometrial hyperplasia as well as to correlate endometrial hyperplasia with the clinical parameters.: It is a retrospective study and included one year data. A total of 125 cases that underwent hysterectomies or endometrial biopsies for abnormal uterine bleeding were recorded with their clinical history. For all cases the histopathology slides were re-evaluated and results were recorded. Epidemiological variables were analyzed by cross tabulation to assess their relationship. Out of 125 cases 53 cases had endometrial hyperplasia, 24 cases were having simple hyperplasia followed by 14 cases with simple hyperplasia without atypia, 9 cases with complex hyperplasia with atypia followed by 6 cases with complex hyperplasia without atypia. 30 to 50 years age group commonly had endometrial hyperplasia & menorrhagia was the common clinical complain in our patients.: In all the females coming to OPD with abnormal uterine bleeding clinical correlation should be properly made with biopsy report of the patient for the proper management of the condition, which avoids landing up of the patient into further complication.
Study of Spectrum of anemia in various age groups
Authors: Pandey Varsha 
Published: September 2021

: Anemia is major health problem world-wide especially in developing countries. Globally 1.62 billion persons are affected. It has grave consequences on human health. The present study evaluates the severity and morphology of anemia in various age groups in rural population. : 1): To study degree and severity of anemia in study population; 2): To study distribution of anemia in various age groups; 3): To study morphological spectrum of anemia in study population. s: The study includes 792 patients having low concentration of hemoglobin for their age & sex. The other hematological parameters and morphology were analyzed. : In our study, females constituted 72.6% (575/792) of study population and male constituted 27.4% (217/792) of population. Pediatric patients (up to 15 years of age) constituted 10% of study population. Out of 792 anemic patients, 439 (55.4%) were having moderate anemia, 228 (28.7%) were having mild anemia & 125 (15.78%) were having severe anemia. Out of 792 anemic patients, 384 (48.4%) were having microcytic hypochromic anemia, 296 (37.37%) were having normocytic normochromic anemia, 84 (10.6%) were having macrocytic anemia and 3.5% were having hemolytic anemia. Out of 792 anemic patients, 439 (55.4%) were having moderate anemia, 228 (28.7%) were having mild anemia & 125 (15.78%) were having severe anemia. In our study anemia was more common in females as compared to males constituting majority of study population which is in concordance with other studies also. Moderate anemia was more common in study population as well as in various sub-groups being in concordance with other studies too. Morphologically microcytic hypochromic anemia was the most common type of anemia especially in adult females. Pregnant females were found to have normocytic normochromic anemia predominantly. Most of the cases of hemolytic anemia was found in children &#60;15years. Similarly macrocytic anemia was found more commonly in adult males. Anemia is the most hematological abnormality found in daily practice, though found in all age groups but quite higher in females. The main objective for diagnosing anemia is to make clinician aware so that they can take measures to prevent and control anemia.
A descriptive study of Endometrial Biopsies in perimenopausal women having Abnormal uterine bleeding
Authors: I Sandhya , Prabhu P Manjushree , S Rao Purnima , Alwa Sameeksha 
Published: September 2021

Abnormal uterine bleeding (AUB) is one of the commonest symptom with which the perimenopausal female visits the gynaecologist accounting for over 70% of all gynecological consultations in that age group. The clinical presentation of AUB can range anywhere menorrhagia, polymenorrhea, polymenorrhagia, metrorrhagia, and menometrorrhagia. Though biopsy is the gold standard it is an invasive procedure and hence often an Ultrasound is used to evaluate the pathology of the endometrium routinely hence, we decided to study the accuracy between radiological ET thickened and its usefulness in detecting endometrial pathology. This study was carried out in the Department of Pathology at AJIMS, Mangalore for a period of 2 years. The sample included endometrial biopies and hysterectomy specimens of perimenopausal women for AUB. The ultrasonographic findings and Histopathological (HPE) reports were analysed. Among 101 cases for AUB, 67 cases were diagnosed as non secretory endometrium. Out of these 67 cases, 49 cases were associated with fibroids. Out of the rest of the AUB cases, 31 of them were diagnosed to have endometrial hyperplasia and 3 cases were diagnosed to have endometrial carcinoma. USG thickness of 17(54%) out of 31 endometrial hyperplasia cases were abnormal. Radiological and pathological evaluation were concordant with diagnosis of AUB associated with fibroids. However only 54% of the endometrial hyperplasia were found to have abnormal endometrial thickness. Radiological evaluation of endometrial thickness is not concordant in 46 % of the cases. This implies that histopathological examination is gold standard diagnostic tool for endometrial abnormalities in perimenopausal women.