An earthquake with JMA magnitude of 6.7 occurred off Yamagata Prefecture at 22:22 on June 18, 2019. In addition to recording seismic intensity 6 upper in Murakami City, Niigata Prefecture, and seismic intensity 6 lower in Tsuruoka City, Yamagata Prefecture, strong shaking occurred from Hokkaido to central Japan. The Earthquake Hazards Division performed a field survey in the damaged area, including visual inspection of the building damage, microtremor observations, and photographing of roof damage by a drone.
Building damage was particularly severe in the coastal region near the border between Yamagata and Niigata Prefectures. In Koiwagata, Tsuruoka City, Yamagata Prefecture, tilt of storehouse, fallen roof tiles, fallen tombstones, and fallen mortar walls were observed.
Based on the drone aerial photos, the percentage of houses with damaged roof tiles is about 30%. In the Fuya, Murakami City, Niigata Prefecture, where JMA seismic intensity 6 upper was recorded, we observed only a few percent of buildings with damaged of roof tiles, a collapse of a retaining wall embankment, and fallen ceiling panels in a gym.
Although strong shaking with seismic intensity 6 upper was recorded, we did not observe any collapsed buildings. The improvement of seismic performance of buildings and the relatively short-period ground motion are likely reasons why there were no casualties for this earthquake.
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