5:15 PM - 6:30 PM
[SSS26-P02] Detecting reflected waves in the triggered seismicity area of Yonezawa, Yamagata-Aizu, Fukushima
Keywords:reflected wave, crustal fluid, triggered seismicity
Events that have occurred by January, 2015 with M larger than 2 (about 2500 events) were investigated. Wave records were downloaded from the Hi-net Home Page of NIED. Up to now, horizontal components of N.ATKH, the station closest to the active region (epicentral distance range of 3~15km), and N.YNZH, the second closest station (8~25km) were checked as follows. Records contaminated by another event were removed. S wave arrivals were picked. Considering the epicentral distribution, eight profiles were set. The records of events with epicentral distance within 0.5km from a profile were displayed along the profile. S wave arrivals between traces were aligned, and a band-pass filter and AGC were applied. Record sections were made for the same component of each station.
Later phases were detected between 1.5~8s after an S wave arrival at both stations. If we assume they were from horizontal reflectors, most of reflectors were situated at 10-20km in depth. The later phases could be traced over 1~2km along a profile. It seems that the phase may be traced for a longer distance, if the method to display a profile is improved. We are going to improve the profile, and determine the position of reflector (or scatterer).