[O-06] Poster presentations by senior high school students

[O06-P77] Tombstone Seismology -Tombstone toppling rate varies with geology

*Asami Yanagisawa¹, *Haruna Iimori¹, Ayano Tago¹, Atsuki Kobayashi¹, Hitomi Yoshida¹ (1. Nagano Prefectural Yashiro High School)

We are Yashiro High School Geoscience Research Group and study tombstone seismology. As a motive, we have been studying tombstone seismology at Yashiro High School since 2009. In the Hokkaido Iburi East Earthquake, the seismic intensity was calculated from the percentage of tombstones that collapsed at a certain point. We assumed that this was due to geological strata. In order to confirm this assumption, we examined the distribution of tombstone collapse rates and strata in the Kumamoto and Hyogo-ken Nanbu earthquakes, and sought the cause of the locations where tombstone collapse rates were low despite their proximity to the epicenter. In both earthquakes, we found that the tombstone collapse rates tended to be lower at sites where the strata were bedrock or reclaimed land. This was considered to be because the natural period of the tombstones did not coincide with the natural period of the stratum and did not resonate with it. We also found that even at sites far from the epicenter, if the strata are Alluvial or Pleistocene, the eigenperiods of the tombstones match and the collapse rate increases.