Lunar seismic exploration.
Seismic experimentation methods to be performed on moon, giving P and S wave travel time curves for models of lunar interior
SEISMIC WAVE↗
SEARCH · Engineering Papers
Results for “SEISMICITY”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Short-period seismic energy radiation patterns from underground nuclear explosions and small- magnitude earthquakes.
Short period seismic radiation patterns from underground nuclear explosions and small magnitude earthquakes, noting propagation characteristics
SEISMIC ENERGY↗
Seismic and Atmospheric Insitu Science Mission
Mission concept for Venus seismicity, meteorology and morphology
Venus↗
Seismic Analysis Issues in Design Certification Applications for New Reactors
The licensing framework established by the U.S. Nuclear Regulatory Commission under Title 10 of the Code of Federal Regulations (10 CFR) Part 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants,” provides requirements for standard design certifications (DCs) and combined license (COL) applications. The intent of this process is the early reso- lution of safety issues at the DC application stage. Subsequent COL applications may incorporate a DC by reference. Thus, the COL review will not reconsider safety issues resolved during the DC process. However, a COL application that incorporates a DC by reference must demonstrate that relevant site-specific de- sign parameters are within the bounds postulated by the DC, and any departures from the DC need to be justified. This paper provides an overview of several seismic analysis issues encountered during a review of recent DC applications under the 10 CFR Part 52 process, in which the authors have participated as part of the safety review effort.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Mapping Diffuse Seismicity Using Empirical Matched Field Processing Techniques
The objective of this project is to detect and locate more microearthquakes using the empirical matched field processing (MFP) method than can be detected using only conventional earthquake detection techniques. We propose that empirical MFP can complement existing catalogs and techniques. We test our method on continuous seismic data collected at the Salton Sea Geothermal Field during November 2009 and January 2010. In the Southern California Earthquake Data Center (SCEDC) earthquake catalog, 619 events were identified in our study area during this time frame and our MFP technique identified 1094 events. Therefore, we believe that the empirical MFP method combined with conventional methods significantly improves the network detection ability in an efficient matter.
15 GEOTHERMAL ENERGY↗
Muons and seismic: a dynamic duo for the shallow subsurface?
Measurements of muon flux and direction at depth provides constraints on density distribution, both spatially and as a function of time. Combination of muon measurements and seismic data provide the potential for improved density estimation and the resolution of elastic parameters.
Inversion↗
Muons and seismic: a dynamic duo for the shallow subsurface?
This paper explores, at a preliminary level, the possibility of merging seismic data, both active and passive, with density constraints inferred from muon measurements. We focus on a theoretical analysis but note that muon experiments are ongoing to test model predictions with experimental data.
58 GEOSCIENCES↗
Geothermal Induced Seismicity National Environmental Policy Act Review
This presentation reviews four National Environmental Policy Act of 1969 (NEPA) documents to understand how Federal agencies, including the U.S. Bureau of Land Management and Department of Energy, review and analyze the potential impacts to the human environment when funding or approving permits for enhanced geothermal system with the potential for induced seismicity.
15 GEOTHERMAL ENERGY↗
FPR Facility Seismic Structural Scoping Study
This is is a seismic scoping study done for a previous project. NASA is gathering information for a trade study on a potential ground test site and would like to review the information in this document for that purpose. The document could also become a reference in the trade study.
33 ADVANCED PROPULSION SYSTEMS↗
A Comprehensive Analysis of Real-World Accelerometer Data Quality in a Global Smartphone-based Seismic Network
The proliferation of low-cost sensors in smartphones has facilitated numerous applications; however, large-scale deployments often encounter performance issues. Sensing heterogeneity, which refers to varying data quality due to factors such as device differences and user behaviors, presents a significant challenge. In this research, we perform an extensive analysis of 3-axis accelerometer data from the MyShake system, a global seismic network utilizing smartphones. We systematically evaluate the quality of approximately 22 million 3-axis acceleration waveforms from over 81 thousand smartphone devices worldwide, using metrics that represent sampling rate and noise level. We explore a broad range of factors influencing accelerometer data quality, including smartphone and accelerometer manufacturers, phone specifications (release year, RAM, battery), geolocation, and time. Our findings indicate that multiple factors affect data quality, with accelerometer model and smartphone specifications being the most critical. In addition, we examine the influence of data quality on earthquake parameter estimation and show that removing low-quality accelerometer data enhances the accuracy of earthquake magnitude estimation.
58 GEOSCIENCES↗
Seismic anisotropy of serpentinite from Val Malenco, Italy
Serpentinites, deformed in mantle subduction zones, are thought to contribute significantly to seismic anisotropy of the upper mantle and have therefore been of great interest with studies on deformation, preferred orientation, and elastic properties. Here we present a combined study of a classical sample from Val Malenco, Italy, investigating the microstructure and texture with state-of-the art synchrotron X-ray and neutron diffraction methods and measuring ultrasonic velocities both with a multi-anvil apparatus and a novel instrument to measure 3-D velocities on spheres. Both, results from diffraction methods and velocity measurements are compared, discussing advantages and disadvantages. From spherical velocities, elastic tensor properties can be derived by inversion. Also from quantitative texture measurements, elastic properties can be modeled by self-consistent averaging. We report good agreement between the velocity and microstructural models is observed.
58 GEOSCIENCES↗
Stress Models of the Annual Hydrospheric, Atmospheric, Thermal, and Tidal Loading Cycles on California Faults: Perturbation of Background Stress and Changes in Seismicity
Stresses in the lithosphere arise from multiple natural loading sources that include both surface and body forces. The largest surface loads include near-surface water storage, snow and ice, atmosphere pressure, ocean loading, and temperature changes. The solid Earth also deforms from celestial body interactions and variations in Earth's rotation. We model the seasonal stress changes in California from 2006 through 2014 for seven different loading sources with annual periods to produce an aggregate stressing history for faults in the study area. Our modeling shows that the annual water loading, atmosphere, temperature, and Earth pole tides are the largest loading sources and should each be evaluated to fully describe seasonal stress changes. In California we find that the hydrological loads are the largest source of seasonal stresses. We explore the seasonal stresses with respect to the background principal stress orientation constrained with regional focal mechanisms and analyze the modulation of seismicity. Our results do not suggest a resolvable seasonal variation for the ambient stress orientation in the shallow crust. When projecting the seasonal stresses into the background stress orientation we find that the timing of microseismicity modestly increases from an ~8 kPa seasonal mean-normal-stress perturbation. The results suggest that faults in California are optimally oriented with the background stress field and respond to subsurface pressure changes, possibly due to processes we have not considered in this study. At any time a population of faults are near failure as evident from earthquakes triggered by these slight seasonal stress perturbations.
58 GEOSCIENCES↗
Variability of near-fault seismic risk to reinforced concrete buildings based on high-resolution physics-based ground motion simulations
Broadband physics-based simulated earthquake ground motions are utilized to characterize the regional-scale seismic risk to modern reinforced concrete (RC) structures. A highly dense dataset of ground motions covering a 100-km urn:x-wiley:00988847:media:eqe3413:eqe3413-math-0001 40-km domain was generated using kinematic fault rupture models with varying rupture characteristics to represent shallow crustal earthquakes and resolved up to frequencies of 5 Hz. Over 40,000 nonlinear response history simulations of short- and mid-rise RC special moment frame buildings were conducted using simulation models that are capable of representing nonlinear behavior and component deterioration effects. The spatial variability of structural risk within a single earthquake scenario and between different rupture scenarios is examined, and the regions of strongest directivity effects and highest structural demands are identified. The structural demands may vary by factor of up to 8.0 at very short distances from the fault, and the large dispersion in the demands decreases significantly beyond a distance of 15 km. The interstory drift and member rotation demands are substantially impacted by important features of the geological structure and the characteristics of the rupture scenarios, particularly the presence of localized high-slip regions. The frequency characteristics of the structures are found to play an important role in determining the effects of near-fault ground motions on the structural response and expected damage. The results of this study suggest that the simulated ground motions, particularly those generated using the hybrid rupture approach, may offer reasonable structural risk estimates for low-frequency structures and conservative estimates for high-frequency structures.
58 GEOSCIENCES↗
Identification of Water-Saturated Zones in a Protective Hydraulic Earthen Structure by Synchronous Electromagnetic and Seismic Sounding
Results of field experiments in synchronized investigation of the protection embankment of the tailing pond of JSC Kovdor Mining and Processing Plant by means of different wave methods of electromagnetic and seismic sounding are presented. A comparative analysis of the data is carried out by means of which boundaries of zones of different degrees of water saturation of the embankment soils may be reliably established. The ranges of velocity of the electromagnetic wave and range of values of the ratio of the velocities of the longitudinal and transverse elastic wave in the transition from dry dense soil of the embankment to moistened soil right up through water-saturated soil are determined.
42 ENGINEERING↗
A Non-perturbative Approach to Computing Seismic Normal Modes in Rotating Planets
In this work, a continuous Galerkin method based approach is presented to compute the seismic normal modes of rotating planets. Special care is taken to separate out the essential spectrum in the presence of a fluid outer core using a polynomial filtering eigensolver. The relevant elastic-gravitational system of equations, including the Coriolis force, is subjected to a mixed finite-element method, while self-gravitation is accounted for with the fast multipole method. Our discretization utilizes fully unstructured tetrahedral meshes for both solid and fluid regions. The relevant eigenvalue problem is solved by a combination of several highly parallel and computationally efficient methods. We validate our three-dimensional results in the non-rotating case using analytical results for constant elastic balls, as well as numerical results for an isotropic Earth model from standard “radial” algorithms. We also validate the computations in the rotating case, but only in the slowly-rotating regime where perturbation theory applies, because no other independent algorithms are available in the general case. The algorithm and code are used to compute the point spectra of eigenfrequencies in several Earth and Mars models studying the effects of heterogeneity on a large range of scales.
58 GEOSCIENCES↗
Strengthening of Old Masonry Walls for out-of-Plane Seismic Loading with a CFRP Reinforced Render
This paper presents part of the results of an experimental campaign for the development of a strengthening technique, aimed at retrofitting old buildings by the application of exterior reinforcing render layers to their masonry walls. The experimental campaign comprised tests with out-of-plane loading on both strengthened and non-strengthened masonry walls. The strengthening layer material, hereby designated as CFRP (Carbon Fibre Reinforced Polymer) reinforcing render, is an innovative material for the seismic retrofitting of masonry walls. The reinforcing render material consists of a lime-based mortar reinforced with a carbon fibre mesh, applied on one or both facings of a masonry wall. This solution was developed to provide the masonry wall with improved mechanical properties, while respecting the main principles for a proper rehabilitation of old buildings.
42 ENGINEERING↗
Seismic monitoring of EGS fracture stimulations at Utah FORGE (Part 1): Time-lapse variations of b-values and Shear-wave Splitting Rates of induced microearthquakes
Characterizing geologic formations near geothermal wells is crucial for efficient extraction of subsurface geothermal energy resources. To monitor effective fracture stimulation of enhanced geothermal systems (EGS), we analyze a catalog of induced microearthquakes to characterize seismicity induced by Phase 2C fracture stimulations of the Utah FORGE project and derive the b-values for 424 induced microearthquakes in three stages of fracture stimulation. Here, we find the time-lapse variations of these b-values. We apply eigenvector rotation and waveform correlation to 3C geophone data to separate fast S 1 and slow S 2 waves, determine their directions, measure their lag time, and calculate the S-wave splitting rate (SSR) for six induced microearthquakes in Stage 1 and 21 in Stage 3. Both SSR values and b-values increase with time. The increase in these values may be related to heavily fractured zones created by fracture stimulations during Stage 2 injections. Large and highly variable SSR values in Stage 3 may reflect heterogeneities in the fracture zones. Time-lapse variations of SSR values and b-values may be one of the most useful approaches to monitoring and characterizing the effectiveness and efficiency of various types of fracture stimulations.
58 GEOSCIENCES↗
Modeling of induced seismicity and ground vibrations associated with geologic CO 2 storage, and assessing their effects on surface structures and human perception
In this paper, we present model simulations of ground motions caused by CO 2 -injection-induced fault reactivation and analyze the results in terms of the potential for damage to ground surface structures and nuisance to the local human population. It is an integrated analysis from cause to consequence, including the whole chain of processes starting from earthquake inception in the subsurface, wave propagation toward the ground surface, and assessment of the consequences of ground vibration. For a small magnitude (M w =3) event at a hypocenter depth of about 1000m, we first used the simulated ground-motion wave train in an inverse analysis to estimate source parameters (moment magnitude, rupture dimensions and stress drop), achieving good agreement and thereby verifying the modeling of the chain of processes from earthquake inception to ground vibration. We then analyzed the ground vibration results in terms of peak ground acceleration (PGA), peak ground velocity (PGV) and frequency content, with comparison to U.S. Geological Survey's instrumental intensity scales for earthquakes and the U.S. Bureau of Mines' vibration criteria for cosmetic damage to buildings, as well as human-perception vibration limits. Our results confirm the appropriateness of using PGV (rather than PGA) and frequency for the evaluation of potential ground-vibration effects on structures and humans from shallow injection-induced seismic events. For the considered synthetic M w =3 event, our analysis showed that the short duration, high frequency ground motion may not cause any significant damage to surface structures, but would certainly be felt by the local population.
54 ENVIRONMENTAL SCIENCES↗