[SSS04-P06] Disaster mainly of stone torii by the Yamagata Offshore Earthquake in 2019
Keywords:Off-Yamagata earthquake in 2019, strong motion, stone toriis, earthquake disaster
A large earthquake 6.7 Mj(according to JMA), called the Yamagata-ken Oki jishin (Yamagata Offshore Earthquake), occurred on 18th June 2019 at 22:22 JST, offshore of Yamagata Prefecture, northwest Japan. There is few human damage luckily, but damage of less than 800 houses occurred near the epicenter around the border of Yamagata and Niigata Prefectures.
Maximum seismic intensity is 6 upper in northern margin of Murakami City, Niigata Prefecture and the second largest seismic intensity if 6 lower in southern margin of Tsuruoka City, Yamagata Prefecture. According to JMA Estimated seismic intensity map. Seismic intensity decreases as moving farther away from the epicenter.
The Author made a survey of damage of stone toriis by the earthquake distributed in Tsuruoka City and northern part of Murakami City. According to prior research of Kawabe (2007) which surveyed damage of 250 stone toriis in Noto Peninsula, direction of strong seismic movement can be provided from the positions of damage of the stone torii as shown in Fig. 1, and converted seismic intensity can be converted from total damage points of individual point of individual place shown as Table 1 and 2.
According to the result of the survey of 135 stone toriis shown in Fig.2, distribution of converted seismic intensity is resembles generally JMA estimated seismic intensity map. but values of converted seismic intensity of several points in Murakami City are larger than JMA estimated seismic intensity. This may be caused by the difference of the calculation method of two seismic intensity. That is, converted seismic intensity depends on pulsed strong motion and JMA estimated seismic intensity depends on the amplitude and fr3equency of seismic wave.
Calculated directions of strong motion of stone toriis in northern Tsuruoka City show the direction to the epicenter, though the directions of strong motion in most of surveyed area direct diagonally to the epicenter. This difference may be caused by the geology of the Neogine non-concrete sediments in northern Tsuruoka City and of rigid granitic rocks in other area.
References:
JMA (2019) Monthly report of earthquake and volcanoes in Japan, June 2019.
Katabe Takayuki (2007) Strong quake motion estimated from the damage of Toriis by the 2007 Noto Peninsula Earthquake in the northwest part of the Noto Peninshurla, Hokuriku distict, Japan -method of examination-. Earth Science, 61, 379-387.
Maximum seismic intensity is 6 upper in northern margin of Murakami City, Niigata Prefecture and the second largest seismic intensity if 6 lower in southern margin of Tsuruoka City, Yamagata Prefecture. According to JMA Estimated seismic intensity map. Seismic intensity decreases as moving farther away from the epicenter.
The Author made a survey of damage of stone toriis by the earthquake distributed in Tsuruoka City and northern part of Murakami City. According to prior research of Kawabe (2007) which surveyed damage of 250 stone toriis in Noto Peninsula, direction of strong seismic movement can be provided from the positions of damage of the stone torii as shown in Fig. 1, and converted seismic intensity can be converted from total damage points of individual point of individual place shown as Table 1 and 2.
According to the result of the survey of 135 stone toriis shown in Fig.2, distribution of converted seismic intensity is resembles generally JMA estimated seismic intensity map. but values of converted seismic intensity of several points in Murakami City are larger than JMA estimated seismic intensity. This may be caused by the difference of the calculation method of two seismic intensity. That is, converted seismic intensity depends on pulsed strong motion and JMA estimated seismic intensity depends on the amplitude and fr3equency of seismic wave.
Calculated directions of strong motion of stone toriis in northern Tsuruoka City show the direction to the epicenter, though the directions of strong motion in most of surveyed area direct diagonally to the epicenter. This difference may be caused by the geology of the Neogine non-concrete sediments in northern Tsuruoka City and of rigid granitic rocks in other area.
References:
JMA (2019) Monthly report of earthquake and volcanoes in Japan, June 2019.
Katabe Takayuki (2007) Strong quake motion estimated from the damage of Toriis by the 2007 Noto Peninsula Earthquake in the northwest part of the Noto Peninshurla, Hokuriku distict, Japan -method of examination-. Earth Science, 61, 379-387.