Watts Bar Nuclear Power Plant Strong-Motion Records of the 12 December 2018 M 4.4 Decatur, Tennessee, Earthquake

2020 ◽  
Vol 91 (3) ◽  
pp. 1579-1592 ◽  
Author(s):  
Vladimir Graizer ◽  
Dogan Seber ◽  
Scott Stovall
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Ground Motion ◽  
Nuclear Power ◽  
Prediction Models ◽  
Ground Motions ◽  
Strong Motion ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Digital Recordings

Abstract The moment magnitude M 4.4 on 12 December 2018 Decatur, Tennessee, earthquake occurred in the eastern Tennessee seismic zone. Although the causative fault is not known, the earthquake had a predominantly strike-slip mechanism with an estimated hypocentral depth of about 8 km. It was felt over a distance of 500 km stretching from Southern Kentucky to Georgia. Strong shaking, capable of causing slight damage, was reported near the epicenter. The Watts Bar nuclear power plant (NPP) is only 4.9 km from the epicenter of the earthquake and experienced only slight shaking. The earthquake was recorded by the plant’s seismic strong-motion instrumentation installed at four different locations. Near-real-time calculations by the plant operators indicated that the operating basis earthquake (OBE) ground motion was not exceeded during the earthquake. We obtained and processed the recorded motions to calculate corrected accelerations, velocities, and displacements. In addition, we computed the Fourier and 5% damped response spectra to compare them with the plant’s OBE. Comparisons of the ground-motion prediction models with the digital recordings at the plant site indicated that recorded ground motions were significantly below the predicted results calculated using the ground-motion prediction models approved for regulatory use. Availability of high-quality, digital recordings in this case helped make a quick decision about the ground motions not exceeding the OBE and hence prevented unnecessary shutdown of the NPP. Availability of earthquake recordings from the four locations in the NPP also presented an opportunity to analyze the linear response of plant structures.

Ground-motion model for subduction earthquakes in northern South America

2021 ◽  
pp. 875529302110275
Author(s):  
Carlos A Arteta ◽  
Cesar A Pajaro ◽  
Vicente Mercado ◽  
Julián Montejo ◽  
Mónica Arcila ◽  
...  
Keyword(s):  
South America ◽  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Motion Prediction ◽  
Depth Range ◽  
Ground Motion Prediction ◽  
Natural Period ◽  
Nazca Plate ◽  
Northern South America

Subduction ground motions in northern South America are about a factor of 2 smaller than the ground motions for similar events in other regions. Nevertheless, historical and recent large-interface and intermediate-depth slab earthquakes of moment magnitudes Mw = 7.8 (Ecuador, 2016) and 7.2 (Colombia, 2012) evidenced the vast potential damage that vulnerable populations close to earthquake epicenters could experience. This article proposes a new empirical ground-motion prediction model for subduction events in northern South America, a regionalization of the global AG2020 ground-motion prediction equations. An updated ground-motion database curated by the Colombian Geological Survey is employed. It comprises recordings from earthquakes associated with the subduction of the Nazca plate gathered by the National Strong Motion Network in Colombia and by the Institute of Geophysics at Escuela Politécnica Nacional in Ecuador. The regional terms of our model are estimated with 539 records from 60 subduction events in Colombia and Ecuador with epicenters in the range of −0.6° to 7.6°N and 75.5° to 79.6°W, with Mw≥4.5, hypocentral depth range of 4 ≤  Zhypo ≤ 210 km, for distances up to 350 km. The model includes forearc and backarc terms to account for larger attenuation at backarc sites for slab events and site categorization based on natural period. The proposed model corrects the median AG2020 global model to better account for the larger attenuation of local ground motions and includes a partially non-ergodic variance model.

Turkey-Adjusted NGA-W1 Horizontal Ground Motion Prediction Models

2016 ◽  
Vol 32 (1) ◽  
pp. 75-100 ◽  
Author(s):  
Zeynep Gülerce ◽  
Bahadır Kargoığlu ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Prediction Models ◽  
Ground Motions ◽  
Site Amplification ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Data Set ◽  
Horizontal Ground Motion ◽  
Strong Ground

The objective of this paper is to evaluate the differences between the Next Generation Attenuation: West-1 (NGA-W1) ground motion prediction models (GMPEs) and the Turkish strong ground motion data set and to modify the required pieces of the NGA-W1 models for applicability in Turkey. A comparison data set is compiled by including strong motions from earthquakes that occurred in Turkey and earthquake metadata of ground motions consistent with the NGA-W1 database. Random-effects regression is employed and plots of the residuals are used to evaluate the differences in magnitude, distance, and site amplification scaling. Incompatibilities between the NGA-W1 GMPEs and Turkish data set in small-to-moderate magnitude, large distance, and site effects scaling are encountered. The NGA-W1 GMPEs are modified for the misfit between the actual ground motions and the model predictions using adjustments functions. Turkey-adjusted NGA-W1 models are compatible with the regional strong ground motion characteristics and preserve the well-constrained features of the global models.

scholarly journals Empirical Spectral Amplification Function for a Reference Site Near Keddara Dam in Algeria using Strong Motion Data.

2021 ◽  
Author(s):  
Faouzi Gherboudj ◽  
Toufiq Ouzandja ◽  
Rabah Bensalem
Keyword(s):  
Ground Motion ◽  
Reference Site ◽  
Ground Motions ◽  
Free Field ◽  
Strong Motion ◽  
Ambient Vibration ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Strong Motion Data ◽  
Motion Data

Abstract This paper deals with empirical spectral amplification function for a reference site (STK) near Keddara dam in Algeria using local strong ground motion of earthquakes of magnitudes Mw 4.0-6.8. Amplification function is obtained as the 5% damped mean spectral ratio of surface observed and the rock predicted ground motions and it is compared to the ambient vibration HVSR which shows a good agreement in terms of fundamental frequency and curve tendency. In addition, recorded ground motions are compared to surface predicted motion with modified GMPE, the site term of the local ground motion prediction equation is adjusted based on the obtained amplification function of the free field STK site. Examples of the M 6.8, M5.4 and M4.7 earthquakes show clearly the advantage of using the adjusted Ground Motion Prediction Equations (GMPE) for predicting surface ground motion. Site effect characterization and the adjusted GMPE presented in this study provide the basis elements toward partially non ergodic site specific-Probabilistic seismic hazard assessment (PSHA) application based on local strong motion data in Algeria.

scholarly journals Ground motions in urban Los Angeles from the 2019 Ridgecrest earthquake sequence

2021 ◽  
pp. 875529302110039
Author(s):  
Filippos Filippitzis ◽  
Monica D Kohler ◽  
Thomas H Heaton ◽  
Robert W Graves ◽  
Robert W Clayton ◽  
...  
Keyword(s):  
Los Angeles ◽  
Ground Motion ◽  
Ground Motions ◽  
Earthquake Sequence ◽  
Motion Prediction ◽  
Ground Motion Prediction Equations ◽  
Prediction Equations ◽  
Ground Motion Prediction ◽  
Velocity Models ◽  
Spectral Accelerations

We study ground-motion response in urban Los Angeles during the two largest events (M7.1 and M6.4) of the 2019 Ridgecrest earthquake sequence using recordings from multiple regional seismic networks as well as a subset of 350 stations from the much denser Community Seismic Network. In the first part of our study, we examine the observed response spectral (pseudo) accelerations for a selection of periods of engineering significance (1, 3, 6, and 8 s). Significant ground-motion amplification is present and reproducible between the two events. For the longer periods, coherent spectral acceleration patterns are visible throughout the Los Angeles Basin, while for the shorter periods, the motions are less spatially coherent. However, coherence is still observable at smaller length scales due to the high spatial density of the measurements. Examining possible correlations of the computed response spectral accelerations with basement depth and Vs30, we find the correlations to be stronger for the longer periods. In the second part of the study, we test the performance of two state-of-the-art methods for estimating ground motions for the largest event of the Ridgecrest earthquake sequence, namely three-dimensional (3D) finite-difference simulations and ground motion prediction equations. For the simulations, we are interested in the performance of the two Southern California Earthquake Center 3D community velocity models (CVM-S and CVM-H). For the ground motion prediction equations, we consider four of the 2014 Next Generation Attenuation-West2 Project equations. For some cases, the methods match the observations reasonably well; however, neither approach is able to reproduce the specific locations of the maximum response spectral accelerations or match the details of the observed amplification patterns.

Directivity in NGA Earthquake Ground Motions: Analysis Using Isochrone Theory

2008 ◽  
Vol 24 (1) ◽  
pp. 279-298 ◽  
Author(s):  
Paul Spudich ◽  
Brian S. J. Chiou
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Strike Slip ◽  
Motion Prediction ◽  
Spectral Acceleration ◽  
Correction Factors ◽  
Ground Motion Prediction ◽  
Earthquake Ground Motions

We present correction factors that may be applied to the ground motion prediction relations of Abrahamson and Silva, Boore and Atkinson, Campbell and Bozorgnia, and Chiou and Youngs (all in this volume) to model the azimuthally varying distribution of the GMRotI50 component of ground motion (commonly called “directivity”) around earthquakes. Our correction factors may be used for planar or nonplanar faults having any dip or slip rake (faulting mechanism). Our correction factors predict directivity-induced variations of spectral acceleration that are roughly half of the strike-slip variations predicted by Somerville et. al. (1997), and use of our factors reduces record-to-record sigma by about 2–20% at 5 sec or greater period.

Research on Earthquake Acceleration Alarm of Nuclear Power Plant

2021 ◽  
Author(s):  
Li Liang ◽  
Pan Rong ◽  
Ren Guopeng ◽  
Zhu Xiuyun
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
False Alarm ◽  
Ground Motion ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Time History ◽  
Seismic Acceleration ◽  
Trigger Signal

Abstract Almost all nuclear power plants in the world are equipped with seismic instrument system, especially the third generation nuclear power plants in China. When the ground motion measured by four time history accelerometers of containment foundation exceeds the preset threshold, the automatic shutdown trigger signal will be generated. However, from the seismic acceleration characteristics, isolated and prominent single high frequency will be generated the acceleration peak, which has no decisive effect on the seismic response, may cause false alarm, which has a certain impact on the smooth operation of nuclear power plant. According to the principle of three elements of ground motion, this paper puts forward a method that first selects the filtering frequency band which accords with the structural characteristics of nuclear power plants, then synthesizes the three axial acceleration time history, and finally selects the appropriate acceleration peak value for threshold alarm. The results show that the seismic acceleration results obtained by this method can well represent the actual magnitude of acceleration, and can solve the problem of false alarm due to the randomness of single seismic wave, and can be used for automatic reactor shutdown trigger signal of seismic acceleration.

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