2020 Volume 129 Issue 4 Pages Cover04_01-Cover04_02
Thousand seismometers had been deployed in the aftershock area of the 2000 Western Tottori earthquake (Mj 7.3) from March 2017 to April 2018. Map shows first P wave polarity distribution for an event that occurred on October 21, 2017 with a magnitude of 3.0. Yellow star shows epicenter. Blue and red dots, plotted at sensor sites, indicate polarity up and down, respectively. Small dots indicate stations with polarity unrecognized. Open star shows epicenter of the mainshock of the Mj 7.3 event. Open squares are locations of Hi-net stations. Polarity distribution is clearly divided into four quadrants, demonstrating that the event is of the strike-slip type.
We used topographic map by Geospatial Information Authority of Japan.