2019 Yamagata earthquake
An earthquake measuring 6.4 struck primarily the Hokuriku region centered on Tsuruoka, Yamagata in Japan, on 18 June 2019 at 10:22 p.m. JST. A tsunami warning was also issued. The event has been officially called the.
Geology
The northwestern side of Honshu lies on the southeastern margin of the Sea of Japan, an area of oceanic crust created by back-arc spreading from the late Oligocene to middle Miocene. The extensional tectonics associated with the spreading formed a series of N-S trending extensional faults and associated basins. The crust in this area is subjected to east-west compression associated with the convergent boundary between the Amur Plate and the Okhotsk Plate. As a result of this strain, the north-south trending extensional faults are reactivated in a reverse sense. The 1964 Niigata earthquake, the 1983 Sea of Japan earthquake, and the 1993 Hokkaidō earthquake were all a result of similar processes.Damage and effects
The magnitude 6.4 earthquake triggered a tsunami advisory for three prefectures in Japan. A tsunami with a height of 10 cm was reported in Niigata. The earthquake damaged a total of 149 homes in Akita, Niigata, and Yamagata prefectures.Casualties
26 people were reported to be injured, mostly by fallen debris.Transportation
Sections of the Nihonkai-Tōhoku Expressway and Yamagata Expressway were closed by the East Nippon Expressway Company. National Route 345 was blocked by fallen debris in Murakami.Utilities
announced that a blackout occurred in parts of Yamagata and Niigata prefectures because of the earthquake, with 1000 customers impacted in Tsuruoka and 200 customers impacted in Sakata. Gas services were interrupted in Niigata Prefecture as a safety measure.Seismic intensity
This chart describes the maximum perceived shaking using the Japan Meteorological Agency seismic intensity scale, or Shindo scale, for the earthquake throughout the impacted area.| JMA seismic level | Prefecture | City or municipality name |
| 6 upper | Niigata | Murakami |
| 6 lower | Yamagata | Atsumigawa, Tsuruoka |
| 5 upper | Yamagata | Atsumi, Tsuruoka, Michidamachi, Tsuruoka |
| 5 lower | Niigata | Nagaoka, Kashiwazaki, Aga |
| 5 lower | Yamagata | Other areas in Tsuruoka, Sakata, Ōkura, Mikawa |
| 5 lower | Akita | Yurihonjō |