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|NKS Programme Area:||NKS-R|
|Research Area:||Risk analysis and probabilistic methods|
|Report Title:||Modelling as a tool to augment ground motion data in regions of diffuse seismicity - Progress 2015|
|Authors:||Ludovic Fülöp, Vilho Jussila, Björn Lund, Billy Fälth, Peter Voss, Jari Puttonen, Jouni Saari, Pekka Heikkinen, |
|Abstract:||De-aggregation of probabilistic hazard assessment (PSHA) results show that the dominating source of vibrations with engineering significance to NPP safety is from mid-magnitude earthquakes located at close distances to the plant. This region is called the “near-field” and is known for its particularities when compared to “far-field”. For example, significant duration of the ground motions is shorter, corresponding to S-wave and surface wave arrivals; there are distinctive high velocity peaks in the ground motions and vertical shaking components may exceed horizontal components. These particularities are known to have design consequences, but are often overlooked by engineering codes.
In Fennoscandia, near-field observations of larger magnitude (M>3) earthquakes are missing, and modelling is the only way to supplement the existing empirical data underpinning the attenuation equations in the PSHA studies.
In the ADdGROUND project, during the financial year 2015, we confirmed the near-source effect in small magnitude earthquake recordings in Finland and developed modeling skills and tools to generate synthetic near-field accelerograms starting from process of the fault rupture. We calibrated models with the very few existing near-field measurement cases of small earthquakes. In this report we also highlight some of the potential design consequences of near-source earthquakes to nuclear installations. The consensus seems to be that the destructive potential of these types of earthquakes is generally low. However, they can produce surprisingly larger acceleration values in the range of high frequencies, and can generate high strain rates in the loaded structures and components. In nuclear installations, with stiff components the effect of high frequency shaking should be carefully considered.
Within the ADdGROUND activity we organized two workshops, one on the 8th May 2015 in Espoo, and the second in Copenhagen (15th December 2015). The outcomes have been presented to the nuclear community in the Nordic countries in the NKS Seminar “Nordic perspectives of Fukushima: Where are we now and where do we go? Joint NKS-R and NKS-B Seminar” in Stockholm (12-13.01.2016).|
|Keywords:||nuclear power plant safety, earthquake, near-field effects, fault source modeling|
|Publication date:||03 May 2016|
|Number of downloads:||378|