A5055181640- Seismic Waves and Analysis
- Seismology and Earthquake Studies
- earthquake and tectonic studies
- Seismic Performance and Analysis
- Seismic Imaging and Inversion Techniques
- Structural Health Monitoring Techniques
- Advanced Fiber Optic Sensors
- Ultrasonics and Acoustic Wave Propagation
- Geotechnical Engineering and Underground Structures
- Elasticity and Material Modeling
- Earthquake Detection and Analysis
- Landslides and related hazards
- High-pressure geophysics and materials
- Vibration and Dynamic Analysis
- Rheology and Fluid Dynamics Studies
- Masonry and Concrete Structural Analysis
- Geophysics and Sensor Technology
- Elasticity and Wave Propagation
- Geological Modeling and Analysis
- Geotechnical Engineering and Soil Mechanics
- Geophysics and Gravity Measurements
- Geotechnical and Geomechanical Engineering
- Numerical methods in engineering
- Structural Response to Dynamic Loads
- Infrastructure Resilience and Vulnerability Analysis
United States Geological Survey
2005-2024
Pacific Island Ecosystems Research Center
2021
United States Department of the Interior
1987-2012
Menlo School
1994-1995
Stanford University
1992
University of California, Santa Cruz
1992
Kyoto University
1992
Primary Source
1987
abstract Measurements of ground motion generated by nuclear explosions in Nevada were made for 37 locations near San Francisco Bay, California. The results compared with the 1906 earthquake intensities and strong-motion recordings March 22, 1957. show marked amplitude variations which are related consistently to geologic setting recording site. For sites underlain a layer younger bay mud or artificial fill, maximum horizontal velocities generally increased thickness as much ten times greater...
Recent borehole-geotechnical data and strong-motion measurements constitute a new empirical basis to account for local geological conditions in earthquake-resistant design site-dependent, building-code provisions. They provide unambiguous definitions of site classes rigorous estimates site-dependent amplification factors terms mean shear-wave velocity. A simple four-step methodology estimating response spectra is specified herein. Alternative techniques commentary are presented each step...
Recent code provisions for buildings and other structures (1994 1997 NEHRP Provisions, UBC) have adopted new site amplification factors a procedure classification. Two amplitude-dependent are specified: F short periods v longer periods. Previous codes included only long period factor S did not provide factor. The classification system is based on definitions of five classes in terms representative average shear wave velocity to depth 30 m (V¯ s ). This definition permits sites be classified...
abstract Measurements of ground motion generated by nuclear explosions in Nevada have been completed for 99 locations the San Francisco Bay region, California. The recordings show marked amplitude variations frequency band 0.25 to 3.0 Hz that are consistently related local geological conditions recording site. average spectral amplifications observed vertical and horizontal motions are, respectively: (1, 1) granite, (1.5, 1.6) Franciscan Formation, (3.0, 2.7) Santa Clara (3.3, 4.4) alluvium,...
Abstract Strong ground motions recorded at 34 sites in the San Francisco Bay region from Loma Prieta earthquake show marked variations characteristics dependent on crustal structure and local geological conditions. Peak horizontal acceleration velocity inferred for underlain by “rock” generally occur transverse component of motion. They are consistently greater with lower attenuation rates than corresponding mean value predicted empirical curves based previous strong-motion data. Theoretical...
abstract The general theory of viscoelasticity, which accounts for elastic as well anelastic linear behavior materials, predicts that two types S waves propagate in earth materials. particle motion an inhomogeneous plane wave type I is elliptical the defined by directions propagation and attenuation, while II perpendicular to this plane. S-wave incident upon a boundary attenuation generates only same type. General characteristics type-II reflected refracted at boundaries are: these whenever...
The mathematical framework for describing plane waves in elastic and linear anelastic media is presented. Theoretical results suggest that the nature of materials distinctly different from materials. In only type inhomogeneous wave (P or S) can propagate one which planes constant phase are perpendicular to amplitude. However, this cannot propagate. For an P S particle motion elliptical, velocity less than a corresponding homogeneous wave, maximum attenuation greater direction energy flow not...
ABSTRACT Seismic tomography is the most abundant source of information about internal structure Earth at scales ranging from a few meters to thousands kilometers. It constrains properties active volcanoes, earthquake fault zones, deep reservoirs and storage sites, glaciers ice sheets, or entire globe. contributes outstanding societal problems related natural hazards, resource exploration, underground storage, many more. The recent advances in seismic are being translated nondestructive...
The reflection and refraction of general (homogeneous or inhomogeneous) plane P type-I S(SV) body waves incident on boundaries are considered for linear viscoelastic solids. Reflection—refraction laws, physical characteristics the waves, nature critical angles examined in detail at welded a free surface. General visco-elasticity with no low-loss approximations predicts that contrasts intrinsic absorption give rise to inhomogeneous reflected refracted elliptical particle motions, velocities...
The Mw 6.0 Parkfield earthquake struck central California at 17:15:14 UTC on 28 September 2004. epicenter was located 11 km southeast of the rural town Parkfield, adjacent to Gold Hill and San Andreas Fault (Figure 1). Integrated Seismic Network (CISN) reported that hypocenter 35.819°N, 120.364°W a depth 8.8 km. From distribution aftershocks from models seismograms, strain changes, geodetic displacements earthquake, it appears rupture propagated northwest along its beneath Middle Mountain....
Microprocessor technology has permitted the development of a General Earthquake-Observation System (GEOS) useful for most seismic applications. Central-processing-unit control via robust software system functions that are isolated on hardware modules permits field adaptability to wide variety active and passive experiments straightforward modification incorporation improvements in technology. Various laboratory tests numerous deployments set systems have confirmed design goals, including:...
Abstract A comparative ground response study at sites in the Los Angeles region is based on extensive strong-motion data set recorded 1971 San Fernando earthquake and 159 three-component recordings of distant nuclear tests Nevada. Amplitude spectral ratios computed for test over those frequency bands which there an adequate signal-to-noise ratio provide statistically stable estimates local related to type geologic conditions. Comparison from with that 28 same show corresponding amplitude are...
Near-field observations of high-precision borehole strain and pore pres- sure, show no indication coherent accelerating or pressure during the weeks to seconds before 28 September 2004 M 6.0 Parkfield earthquake. Minor changes in rate did occur at a few sites last 24 hr earth- quake but these are neither significant nor have form expected for slip coalescence initiating fault failure. Seconds event, is stable 10 � 11 level. Final prerupture nucleation hypocentral region constrained moment...
The analyses presented in the preceding six papers show that geologic setting of San Francisco Bay region has a dominant influence on potential earthquake hazards. strong correlation between conditions and amount damage 1906 emphasizes importance this demonstrates need for seismic zonation. Seismic zonation can provide logical basis preparation special-purpose land-use maps that, with appropriate public policy, would be significant step toward reducing currently expected catastrophic effects...
The analytic solution for a Rayleigh-type surface wave on linear viscoelastic half-space is obtained. general predicts several properties of the distinct from those predicted by elasticity. velocity, absorption coefficient, and displacement field are described theoretically.
Site-response coefficients, F a and v , used in U.S. building code provisions are based on empirical data for motions up to 0.1 g. For larger they theoretical laboratory results. The Northridge earthquake of 17 January 1994 provided significant new set 0.5 These together with recent site characterizations shear-wave velocity measurements provide estimates the coefficients at base accelerations g Site Classes C D. as well their decrease increasing acceleration level consistent 95 percent...
Incorrect versions of Figures 5 and 6 containing normalization errors were accidentally published by Borcherdt (2002). They should be replaced with the figures shown here. The text tabulated regression values in (2002) …
Abstract The physical characteristics for general plane-wave radiation fields in an arbitrary linear viscoelastic solid are derived. Expressions the of inhomogeneous wave fields, derived terms those homogeneous utilized to specify and a set reference curves P S solids as function inhomogeneity intrinsic material absorption. expressions show that increase causes velocity decrease, fractional-energy loss (Q−1) increase, deviation maximum energy flow with respect phase propagation elliptical...
A general computer code, developed to calculate anelastic reflection‐refraction coefficients, energy flow, and the physical characteristics for P , S ‐I, ‐II waves, quantitatively describes wave fields in media that do not exist elastic media. Consideration of incident on boundaries between shows scattered experience reductions phase speeds, increases maximum attenuation Q −1 directions flow distinct from propagation. Each these changes are shown vary with angle incidence. Finite relaxation...
Direct evidence of site distortion P - and S -wave microearthquake source spectra at Oroville, California, is presented. The data were gathered by placing vertical three-component seismometers 90 m intervals in a 500 borehole through the Cleveland Hill normal fault, on which 1975, ML = 5.7 Oroville earthquake took place. High-pressure, hydraulic locking mechanisms used to firmly lock seismometer packages against wall. Digital, event-triggering GEOS recorders receive data. Some 30 seismic...
The analytic solution for a Rayleigh-type surface wave on linear viscoelastic half-space is obtained. general predicts several properties of the distinct from those predicted by elasticity. velocity, absorption coefficient, and displacement field are described theoretically.