Development of methods for evaluating active faults

The HERP report for long-term evaluation of active faults and the NSC safety review guide with regard to geology and ground of site were published on Nov. 2010 and on Dec. 2010, respectively. With respect to those reports, our investigation is as follows; (1) For assessment of seismic hazard, we estimated seismic sources around NPPs based on information of tectonic geomorphology, earthquake distribution and subsurface geology. (2) For evaluation on the activity of blind fault, we calculated the slip rate on the 2008 Iwate-Miyagi Nairiku Earthquake fault, using information on late Quaternary fluvial terraces. (3) To evaluate the magnitude of earthquakes whose sources are difficult to identify, we proposed a new method for calculation of the seismogenic layer thickness. (4) To clarify the activities of active faults without superstratum, we carried out the color analysis of fault gouge and divided the activities into thousand of years and tens of thousands. (5) For improving chronology of sediments, we detected new widespread cryptotephras using mineral chemistry and developed late Quaternary cryptotephrostratigraphy around NPPs. (author)