How Well We Are Predicting High-Frequency Response Spectra for the CEUS?
Description:
Analysis of the NGA-East database developed in 2014 shows clear deficiency in high frequency recordings in the CEUS with less than 40 records with Mw>5.0 at distances R<100 km. In the meantime, nuclear industry is using Westinghouse AP1000 Hard Rock High Frequency (HRHF) response spectrum (developed before 2009) for nuclear power plants design and license applications. Horizontal HRHF peaks at 30 Hz while vertical one at ~45 Hz. The HRHF spectrum was developed based on a limited amount of data before NGA-East was made available. This raises the question: Is HRHF needs to be updated in light of new data?
Ground Motion Models (GMMs) G-16 and G-16v2 (Graizer, 2016 and 2017) were developed using the NGA-East database. It was recently validated against strong motion recordings from the 2016 Oklahoma Cushing MW 5.0 and Pawnee MW 5.8 earthquakes. In the constantly updated Center for Engineering Strong Motion Data (CESMD) database we found only two earthquakes in the CEUS with MW≥5.0 well recorded in the vicinities of the epicenters by modern digital accelerographs with a relatively high sampling rate of 200 samples/sec. Cushing event has 6 recordings at epicentral distances of 1.6 to 84 km and Pawnee has 19 recordings at 42.8 to 163 km. It was shown that both G-16 and G-16v2 models perform well compared to high quality recorded strong motion data. The G-16v2 model has overall lower residuals especially at high (10-100 Hz) and low (0.1-1.0 Hz) frequency ranges.
G-16 and G-16v2 models were used to calculate CEUS spectral shapes for earthquakes with 5≤MW≤8 and distances 1-400 km for soil (Vs=300 m/s), B-C boundary (Vs=760 m/s) and rock (Vs=2800 m/s) profiles. We concluded that HRHF spectral shape is shifted too much toward high frequencies, most importantly not enveloping average hard rock spectrum around 7-20 Hz. We recommend reassessing the HRHF based on the currently available information. We also recommend recording all earthquake strong motion data in the CEUS with a sampling rate not less than 200 samples/sec to allow constraining high frequency spectral models.
Session: High-frequency Ground Motion Measurements, Assessments and Predictions [Poster]
Type: Poster
Date: 4/18/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Vladimir Graizer
Student Presenter: No
Invited Presentation:
Authors
Vladimir Graizer Presenting Author Corresponding Author vladimir.graizer@nrc.gov Nuclear Regulatory Commission |
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How Well We Are Predicting High-Frequency Response Spectra for the CEUS?
Category
High-frequency Ground Motion Measurements, Assessments and Predictions