Determination of dip direction for the 2007 Chuetsu-oki earthquake from relocation of aftershocks using arrival times determined by cross-correlation

Abstract

Waveform correlations were used to redetermine P arrival times at 31 stations for a selected set of 321 after-shocks of the 2007 Chuetsu-oki earthquake. These data were used with several different relocation techniques, 1-D velocity structure, 3-D velocity structure using SIMULPS12, 1-D velocity structure using hypoDD, and 3-D velocity structure using tomoDD. The results from all of these methods show a consistent southeast dipping trend for the entire aftershock sequence. The same pattern is also seen for the time period before the largest aftershock. These results indicate that the mainshock fault dips to the southeast. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.