Looking for Kappa in the U.S. and the U.K. Using Noise Modeling
Description:
In this contribution we combine our experiences from two PSHA studies (using SSHAC protocol) performed for nuclear facilities: Idaho National Laboratory project in the US and Bradwell B project in the UK. We share and discuss the challenge of estimating high-frequency site attenuation, namely the spectral decay parameter kappa. The data quality assessment stage was crucial in identifying the usable data and their usable frequency band, especially at high frequencies. Several issues made the work particularly challenging in both cases, necessitating careful consideration of uncertainties: 1. All recordings came from distances larger than 100 km, significantly increasing epistemic uncertainties stemming from regional (path) attenuation and variability in crustal properties. 2. Most of the recordings were of small magnitude, so that the stress drop (corner frequency) uncertainty became a definitive factor in selecting the usable bandwidth and hence the appropriate estimation methods for kappa. 3. The uncertainties from the trade-off between site attenuation and site amplification were often considerable. 4. The datasets were small and of poor quality, with low signal strength, and many of the recordings were unusable according to typical signal-to-noise criteria. Such limitations were addressed by a signal-enhancing technique based on stochastic noise modeling. This models the noise that contaminates the earthquake signal and corrects the spectrum for it, rather than avoid it. Thus, the recorded data were rendered usable at much higher frequencies than traditionally possible, and in some cases heretofore unusable recordings were added, enhancing the datasets in quality and quantity.
Session: Assessing Seismic Hazard for Critical Facilities and Infrastructure – Insights and Challenges - II
Type: Oral
Date: 5/3/2024
Presentation Time: 05:30 PM (local time)
Presenting Author: Olga-Joan
Student Presenter: No
Invited Presentation:
Authors
Olga-Joan Ktenidou Presenting Author Corresponding Author olga.ktenidou@noa.gr National Observatory of Athens |
Erion-Vasilis Pikoulis pikoulis@ceid.upatras.gr University of Patras |
Robert Darragh bbalindavis@gmail.com Pacific Engineering and Analysis |
Walter Silva pacificengineering@juno.com Pacific Engineering and Analysis |
Guillermo Aldama-Bustos Guillermo.Aldama-Bustos@jacobs.com Jacobs |
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Looking for Kappa in the U.S. and the U.K. Using Noise Modeling
Category
Assessing Seismic Hazard for Critical Facilities and Infrastructure – Insights and Challenges