Download or read book Characterizing the Shear Wave Velocity Profile at the Seismic Network Stations in Israel written by Yuval Peleg and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "... In this study, we develop an indispensable database of Vs profiles in the location of 32 network stations in Israel, using the ReMi (Refraction Microtremor) method (Louie, 2001). ... " -- from the abstract.

Download or read book Shear Wave Velocity Measurements for Subsurface Characterization written by Angela Lydia Lodge and published by . This book was released on 1994 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Shear Velocity Structure in NE China and Characterization of Infrasound Wave Propagation in the 1 210 Kilometer Range written by and published by . This book was released on 2008 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We continued the operation of the Southern Methodist University-Institute of Geophysics, China Earthquake Administration (SMU-IGPCEA) broadband seismic network through May 2008 using Program for the Array Seismic Studies of the Continental Lithosphere (PASSCAL) instrumentation. The operating network included three stations northwest of Beijing and 10 stations in Xiuyan. Lisoning Province, NE China. At the end of May, the PASSCAL instrumentation was returned to the U.S. During the 5.5-year operation, we collected approximately 600 Gb of miniSEED data. Most of the data have been archived at the Incorporated Research Institutes for Seismology (IRIS) data center. This high-quality dataset has already provided us the opportunity to study the detailed velocity structure beneath the Huailai Basin and Haicheng in NE China using both teleseismic and regional signals. We are expanding our joint inversion of teleseismic receiver functions and surface wave phase velocities for crustal shear velocity structure from the Huailai Basin to the Huabei area using data from SMU-IGPCEA broadband seismic network with additional data provided by 48 broadband seismic stations in this region.

Download or read book Development of Shear Wave Velocity Profiles in the Deep Sediments of the Mississippi Embayment Using Surface Wave and Spectral Ratio Methods written by Jonathan Pqul Bailey and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The deep soils of the Mississippi Embayment in the central United States will have a significant influence on earthquake ground motions generated by the New Madrid Seismic Zone. The seismic properties of these soils, which extend to depths of over 1000 meters in some areas, are poorly characterized at depths below 60 to 100 meters. This study presents shear wave velocity (Vs) profiles determined from Spectral-Analysis-of-Surface-Waves (SASW) measurements performed at eleven sites in Arkansas, Tennessee, and Missouri. These measurements were performed using the low-frequency field vibrator developed as part of the NSF Network for Earthquake Engineering Simulation (NEES) program. Shear wave velocity profiles were developed to depths of approximately 220 meters at eleven sites located throughout the Mississippi Embayment. In addition to the SASW measurements, ambient noise measurements of horizontal and vertical ground motions were performed to estimate the average Vs over the full profile depth using the H/V spectral ratio method. The Vs profiles derived from the SASW measurements compared well with Vs reference profiles that have been developed for the Mississippi Embayment and used in recent site response studies of the region. The observed variability of the profiles was found to be in general agreement with past assumptions used for the deep soil and correlated with changes in soil lithology. Relationships between the soil formations and Vs were consistent with past studies and provided information to greater depths. Lastly the H/V spectral ratio measurements were successfully applied at each of the eleven sites, but appeared to overestimate the average Vs.

Download or read book Seismic Applications to Reservoir Characterization and Shear wave Velocity Determination written by Siamak Hassanzadeh and published by . This book was released on 1988 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reducing Uncertainties in the Velocities Determined by Inversion of Phase Velocity Dispersion Curves Using Synthetic Seismograms written by Seyed Mehrdad Hosseini and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Characterizing the near-surface shear-wave velocity structure using Rayleigh-wave phase velocity dispersion curves is widespread in the context of reservoir characterization, exploration seismology, earthquake engineering, and geotechnical engineering. This surface seismic approach provides a feasible and low-cost alternative to the borehole measurements. Phase velocity dispersion curves from Rayleigh surface waves are inverted to yield the vertical shear-wave velocity profile. A significant problem with the surface wave inversion is its intrinsic non-uniqueness, and although this problem is widely recognized, there have not been systematic efforts to develop approaches to reduce the pervasive uncertainty that affects the velocity profiles determined by the inversion. Non-uniqueness cannot be easily studied in a nonlinear inverse problem such as Rayleigh-wave inversion and the only way to understand its nature is by numerical investigation which can get computationally expensive and inevitably time consuming. Regarding the variety of the parameters affecting the surface wave inversion and possible non-uniqueness induced by them, a technique should be established which is not controlled by the non-uniqueness that is already affecting the surface wave inversion. An efficient and repeatable technique is proposed and tested to overcome the non-uniqueness problem; multiple inverted shear-wave velocity profiles are used in a wavenumber integration technique to generate synthetic time series resembling the geophone recordings. The similarity between synthetic and observed time series is used as an additional tool along with the similarity between the theoretical and experimental dispersion curves. The proposed method is proven to be effective through synthetic and real world examples. In these examples, the nature of the non-uniqueness is discussed and its existence is shown. Using the proposed technique, inverted velocity profiles are estimated and effectiveness of this technique is evaluated; in the synthetic example, final inverted velocity profile is compared with the initial target velocity model, and in the real world example, final inverted shear-wave velocity profile is compared with the velocity model from independent measurements in a nearby borehole. Real world example shows that it is possible to overcome the non-uniqueness and distinguish the representative velocity profile for the site that also matches well with the borehole measurements.

Download or read book Discrimination of Seismic Sources Using Israel Seismic Network written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We addressed the problem of automated event discrimination in both the local and teleseismic ranges using the Israel Seismic Network, as an example of a dense regional seismic network. A new high resolution technique was developed, based on multistation representation of the seismic signal: spectral semblance, measuring coherency of spectral shapes, and velogram, characterizing kinematic features. Semblance and energy spectral ratio statistics, applied to a wide variety of local and teleseismic events, showed, for specific spectral bands, almost total separation of explosions and earthquakes. Efficient automated classifiers based on combinations of different physical features of the events have been designed. The discrimination results for the teleseismic data were compared for the ISN and NORESS, showing almost equivalent performance. Noise recordings and teleseismic signals were used to evaluate the ISN detectability by array technique, including adaptive beamforming, optimal detectors, maximum likelihood estimators and phase correlation analysis, applied to the ISN subnetworks with promising results. Experimental relationships between charge weight and magnitude for local single quarry shots and underwater Dead Sea explosions with outstanding high coupling were developed, providing a basis for the execution of effective calibration explosions currently lacking in the region.

Download or read book Shear Wave Velocity Measurement Guidelines for Canadian Seismic Site Characterization in Soil and Rock written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2012/13, Natural Resources Canada released a multi-volume series of Canadian geohazard-related guidelines for geoprofessionals. One of these volumes addresses technical and non-technical topics specific to the measurement of shear wave velocities (Vs) for the assignment of seismic site categories, compliant with the 2010 National Building Code of Canada (NBCC). The volume covers the theory and limitations of 13 current and emerging Vs measurement techniques, and includes key references, current states of engineering practice, data collection procedures and processing techniques, and recommended reporting requirements for each method. Guidance is also provided on complimentary geophysical techniques for subsurface site reconnaissance. We anticipate that these Guidelines will be widely used by geophysicists, geotechnical engineers, municipal building code departments, and others who are involved in seismic site classification following the 2010 NBCC.

Download or read book Seismological Research Letters written by and published by . This book was released on 2006 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variation of Shear Wave Velocity with SPT N Values in the City of Sharjah written by Niamatullah Haji Bismillah and published by . This book was released on 2014 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Modern building codes require the evaluation of a shear wave velocity profile of the foundation soils for a dynamic analysis of structures and sites to occur. Wave velocities are typically evaluated by conducting laboratory and field tests. Due to the rapid pace of development in the UAE,consultants often rely on shear wave velocity (VS) obtained from correlations of shear wave velocity (VS) with N values from Standard Penetration Tests (SPT). Significant variations in previous studies that predict wave velocities justifythis new study in order to develop correlations specific to the region and applicable to areas of similar geology. These variations can be attributed to factors such as biases in conducting field tests and shortcomings in seismic techniques. This study presents the correlations developed between wave velocity and N values for the city of Sharjah by performing seismic tests in various locations. The velocity profiles are evaluated by using vertical geophones that are traditionally used, as well as, horizontal geophones to evaluate their ability in calculating similar profiles. The analysis of surface waves for velocity evaluation is preferred due to its ability in delineating hidden layers of weaker velocities and for the better characterization of shallow depths from the generation of higher frequency phases. The benefits of using a seismic technique based on surface waves are presented and the results of the regression of VS-N pairs are compared with the findings of previous studies discussed here. The effect of using horizontal and vertical geophones on the results is evaluated in order to validate the theoretical basis of particle motion during the propagation of surface waves. The results indicate many previous models underestimate the wave velocity as function of N valuesas compared to the proposed model, especially at N values larger than 15. Most recent studies, however, tend to agree with the prediction model of this study;only one model significantly overestimates the shear wave velocity. The velocity profiles computed from horizontal and vertical geophones agree, indicating that the theoretical basis of elliptical particle motion with both horizontal and vertical components in the propagation of surface waves is valid. "--Abstract.

Download or read book Vertical Shear wave Velocity Profiles Generated from Spectral Analysis of Surface Waves written by Dr. Neil Anderson and published by . This book was released on 2003 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface wave (Rayleigh wave) seismic data were acquired at six separate bridge sites in southeast Missouri. Each acquired surface wave data set was processed [spectral analysis of surface waves (SASW)] and transformed into a site-specific vertical shear-wave velocity profile (SASW shear-wave velocity profile). The SASW shear-wave velocity profiles generated for each bridge site were compared to other geotechnical data including seismic cone penetrometer shear-wave velocity profiles, cross-borehole shear-wave velocity profiles, and borehole lithology logs. The geotechnical data presented herein indicate the SASW shear-wave velocity profiles correlate well with subsurface lithology logs and available cross-borehole shear-wave velocity control. More specifically, clays, silts and sands exhibit relatively characteristic SASW shear-wave velocities, which increase incrementally with increasing depth of burial. The authors believe these correlations demonstrate that SASW shear-wave velocities are reliable.

Download or read book A Shear Wave Velocity Profile of the Mojave Block from Teleseismic P waveforms written by Philip Arthur Wilhelm and published by . This book was released on 1985 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of Laboratory and Field Techniques to Measure Shear Wave Parameters Frequency Effects written by Hassan Ali and published by . This book was released on 2015 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, significance of correctly evaluating the dynamic properties of soil has been widely recognized by the research community. Among various parameters, shear wave velocity and damping ratio has been recognized as the key parameter for the soils subjected to dynamic loading. The shear wave velocity is used in the geotechnical assessments for site characterization, ground response analysis, and liquefaction potential. The dynamic properties of the soils can be attained in the lab or in-situ. The dynamic soil properties are dependent on different state parameters, such as, void ratio, confining stress, water content, strain levels, and drainage conditions. Apart from the influence of the above parameters, the dynamic soil parameters are also affected by the frequency and the amplitude of the dynamic load applied to the soil. The in-situ tests compliments the laboratory testing in the evaluation of the dynamic soil parameters. Although, correlations can be used to estimate the in-situ parameters but a direct measurement is necessary. To develop a greater confidence of the results of the in-situ tests, it is helpful to compare the field results to conventional laboratory tests. In the RC testing, the effect of base stiffness has a significant effect on shear modulus and damping values. In literature, only two studies have shown the effect of base fixidity. In this thesis, the issue is addressed by testing sand and clay sample on traditional bench and isolation table. In addition to base fixidity, coupling between the specimen and base platen is also very critical. Radial blades in top and bottom platen are introduced along with porous stone fixed underneath the blades. Aluminum probes are recommended for the calibration of the RC device, however, the effect on shear modulus and damping as function of shear strain is not well studied. Therefore, the stiff probe is tested from low to large strains and effect on damping ratio is studied. Finally, a new BE method is proposed to understand the estimation of shear wave velocity at higher frequencies. Due to the large variation in the interpretation of the BE tests results, there is no standard method for the estimation of the shear wave velocity. In this thesis, a new calibration procedure using state of the art laser vibrometer is used to understand the bending behavior of benders in air and in tip to tip configuration. Shear wave velocity comparison between RC and BE tests is done in usual practice, however, the frequency effects from these two tests are not well stated. In this study, the frequency effects are studied and a new methodology, modified frequency domain method, is introduced and tested on dry specimen. The results of the BE tests match well with the RC test values. MASW is a practiced field test to evaluate the shear wave velocity profile for geomaterials, however, the effect of frequency in the case of an anomaly has not been well understood. Therefore, this study uses numerical simulations and a lab scale model to study these effects. In addition, the effect of actual accelerometers on the measurements is studied for the first time using a high frequency laser vibrometer. The frequency effects in field theory of the MASW and SCPT is also studied to address the actual limitations in the analysis of SCPT data without the consideration of frequency effects. Based on the objective, this research focuses on: (1) the study of the laboratory resonant column and bender element tests, (2) numerical simulations and laboratory surface waves testing, and (3) field testing using surface waves and seismic cone penetration method for the estimation of shear wave parameters with emphasis on the frequency effects. An important aspect of the laboratory testing is the calibration of the equipment. Standard procedures are available for the calibration of the resonant column (RC) device, however, the same is not true for the bender element (BE). In this study, the bender elements are calibrated using three different configurations, tip-to-tip, aluminum rods, and using state-of-art laser vibrometer. The State of art laser vibrometer is used to characterize the bending behavior of the bender elements showing the resonance frequency of 12 kHz and damping of 2 % when vibrating in air. The top and bottom platen of RC device were modified to allow better coupling between the specimen and benders. Radial blades were introduced to account for coupling of stiff clay specimens. Four different soils (sand, stiff clay, mine paste, and leda clay) were tested in this study. The results of the tests, from the RC and the BE tests, were analyzed in the time and the frequency domains. Comparison of the results show, a maximum of 45 $\%$ difference in the velocity obtained from the RC and BE tests. Leda clay tests were done on the modified base platens and the difference in the Vs between the RC and BE is 6% compared to the stiff clay specimen where the difference is 28% To study the difference in the Vs values between the RC and BE, a new modified frequency domain method for BE testing is presented. The method was applied to the sand specimen. The sample is excited with a frequency sweep ranging from 0 to 52 kHz and change in unwrapped phase, between the input excitation and output response, is evaluated outside the range of resonant peaks of the specimen. The Vs values from the two tests match well for the frequency range between 29 and 23 kHz, with overall less than 10 % error for the range of confinement range studied in this thesis. Numerical simulations on homogeneous and non-homogeneous medium showed the change in the phase velocity of the Rayleigh waves (R-waves) due to the presence of a void. To introduce non-homogeneity, voids of various size and depth were used. Nine numerical models were analyzed, change in the phase velocity as a function of frequency was observed. A new methodology was introduced in which the receivers were divided into three sections, before, on-top, and after the void. Results from the dispersion curves show that the change in the phase velocity (function of frequency) is between 3% to 50% for different void width and depth. Multichannel analysis of surface waves (MASW) test method was used as the geophysical testing method. The laboratory tests were conducted using three different configurations on sandbox. Two tests involved use of accelerometers as receivers, however, the input source was different. While the third test consisted of using state of art laser vibrometer as receiver. Using the laser vibrometer, 96 surface responses were recorded compared to 12 using accelerometers. The results from the laboratory MASW test showed the frequency effect on the measurements due to the source used in this method. Coupling of the geophone/transducer in surface wave testing is an important issue. Results from the lab test using laser vibrometer showed that the mass loading effect of accelerometer affects the frequency content of the signal. The field MASW and the SCPT tests were done at the University of Waterloo Columbia Lake Test Site (UW-CLTS). The comparison of shear wave velocity from the field MASW and the SCPT shows the average shear wave velocity profile from the two tests, however, importance in not paid to the frequency of the input signal and main frequency difference between the MASW and SCPT tests. In this study, the frequency spectrum from the MASW and the SCPT tests data were analyzed to understand the change in the shear wave velocity at different depths. From the analysis, the percentage change in shear wave velocity between MASW line 1 and SCPT 1 and 2 is more than 90 % for depths between 0 and 2 m, while it reduces to 10 % for depths between 7 and 13 m.

Download or read book Characterization of Shallow Shear Wave Velocity Structures in Southwestern Utah written by Simin Huang and published by . This book was released on 2011 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detection Location and Discrimination of Seismic Events by the Seismic Network of Israel written by A. Shapira and published by . This book was released on 1995 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Israeli Seismic Network (ISN) consists of 36 short period stations distributed throughout the country. In addition, a Broad Band station is operating at the geophysical observatory near Bar Giyyora, Israel (BGIO) and a small aperture seismic array is under construction in the central Negev desert. The ISN is a regional network which aims to monitor the seismicity in the area bounded by latitudes 27. ON - 36.0N and longitudes 32.0E - 38. OE. It is tuned to detect all seismic events of magnitudes ML>2.0 occurring in Israel. Triggered events are routinely analyzed, yielding a seismological bulletin which provides the seismic event source parameters and classifies the events as earthquakes, explosions, possible explosions and distant events. The detection capabilities of the ISN within Israel is proven to be ML>2.0. In many locations around the country, the threshold magnitude is as low as 0.5. Comparisons of the detection performance of the ISN with those of other international organizations has shown the superiority of the ISN in monitoring the eastern Mediterranean and Middle East regions. Less than 10% of the events detected by the ISN are local and regional earthquakes. Most of the detected events are quarry blasts in Israel, Lebanon and Jordan and detonations associated with infrastructure developments. Sonic wave detectors are used to identify quarry blasts. In parallel, ground truth information is used do develop analytical procedures for discrimination. Presently, the azimuth-invariant, low-frequency spectral modulation method is used to identify the quarry blasts and underwater explosions (UWE) caused by ripple firing and bubbling effects, respectively.

Download or read book Upper Mantle Shear Wave Velocity Structure of the East Anatolian Caucasus Region written by Gleb Anatolyevich Skobeltsyn and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the present dissertation, I describe two studies of the regional upper mantle shear wave velocity structure. In order to derive the absolute velocity structure of the upper mantle, I have applied surface wave tomography to model Rayleigh wave phase velocities as a function of period. Then I inverted the Rayleigh phase velocities to obtain shear wave velocities as a function of depth. The resulted high-resolution 3-D shear wave velocity model of the regional upper mantle is characterized by a better depth resolution than any preexisting tomographic models. I also conducted a shear wave splitting analysis using traditional methods and developed a two-layer grid search algorithm in order to infer the upper mantle anisotropic structure. The results of the shear wave splitting analysis for the stations located in Azerbaijan are the first in the region. My 3-D velocity model shows the depth extent of the asthenospheric layer beneath the Turkish and Iranian Plateaus, which does not exceed 200 km and therefore rejects any suggestions of the existence of deep mantle plums in the area. The deep high velocity bodies beneath the Black Sea and northern Iranian Plateau are identified as the remnant slabs of the northern and southern brbranchesf the Neo-Tethys lithosphere. The widespread volcanism and the uplift within the plateau were the result of a gradual steepening of the subducting slab of the southern branch of Neo-Tethys. The shear wave splitting analysis shows evidence of the two-layer anisotropic structure beneath the eastern Caucasus region. The results presented in the dissertation are crucial for the regional seismic hazard analysis.

Download or read book Publications of the Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1997 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: