The was an earthquake of magnitude 6.4 which struck primarily the

Hokuriku region The was located in the northwestern part of Honshu, the main island of Japan. It lay along the Sea of Japan within the Chūbu region, which it is currently a part of. It is almost equivalent to Koshi Province and Hokurikudō area in pre-mod ...

in Japan on 18 June 2019 at 22:22 JST (13:22 UTC). The epicenter was close to the city of

Tsuruoka is a city in Yamagata Prefecture, Japan. , the city had an estimated population of 125,389 in 49,024 households, and a population density of 95.74 persons per km². The total area of the city is . Tsuruoka is the biggest city in Tōhoku region ...

, Yamagata. A

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

warning was also issued.

Geology

The northwestern side of

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island ...

lies on the southeastern margin of the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...

, an area of

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafi ...

created by

back-arc spreading A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of ...

from the

late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/ Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stag ...

to middle Miocene. The

extensional tectonics Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend ...

associated with the spreading formed a series of N-S trending

extensional fault An extensional fault is a fault caused by stretching of the Earth's crust. Stretching reduces the thickness and horizontally extends portions of the crust and/or lithosphere. In most cases such a fault is also a normal fault, but may create a s ...

s and associated

basins Basin may refer to: Geography and geology * Depression (geology) ** Back-arc basin, a submarine feature associated with island arcs and subduction zones ** Debris basin, designed to prevent damage from debris flow ** Drainage basin (hydrology), ...

. The crust in this area is subjected to east–west compression associated with the

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

between the

Amur Plate The Amurian Plate (or Amur Plate; also occasionally referred to as the China Plate, not to be confused with the South China Subplate) is a minor tectonic plate in the northern and eastern hemispheres. It covers Manchuria, the Korean Peninsula ...

and the

Okhotsk Plate The Okhotsk Plate is a minor tectonic plate covering the Kamchatka Peninsula, Magadan Oblast, and Sakhalin Island of Russia; Hokkaido, Kantō and Tōhoku regions of Japan; the Sea of Okhotsk, as well as the disputed Kuril Islands. It was form ...

. As a result of this strain, the north–south trending extensional faults are reactivated in a reverse sense. The

1964 Niigata earthquake Events January * January 1 – The Federation of Rhodesia and Nyasaland is dissolved. * January 5 - In the first meeting between leaders of the Roman Catholic and Orthodox churches since the fifteenth century, Pope Paul VI and Patriarc ...

, the

1983 Sea of Japan earthquake The year 1983 saw both the official beginning of the Internet and the first mobile cellular telephone call. Events January * January 1 – The migration of the ARPANET to TCP/IP is officially completed (this is considered to be the beginning ...

, 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

Twenty-six people were reported to be injured, mostly by fallen debris.

Transportation

Sections of the

Nihonkai-Tōhoku Expressway The is a national expressway in Japan. It is owned and operated by East Nippon Expressway Company. Naming The course of the expressway takes it alongside the coastline of the Sea of Japan (Nihonkai) in the Tōhoku region of Japan. The Niho ...

and

Yamagata Expressway The is a national expressway in the Tōhoku region of Japan. It is owned and operated by East Nippon Expressway Company. Naming The expressway is officially referred to as the Tōhoku Ōdan Expressway Sakata Route. From Tsuruoka Junction to S ...

were closed by the

East Nippon Expressway Company The , abbreviated as , is one of the main operators of expressways and toll roads in Japan. It is headquartered in Kasumigaseki, Chiyoda, Tokyo. The company was established on October 1, 2005 as a result of the privatization of Japan Highway P ...

. National Route 345 was blocked by fallen debris in Murakami.

Utilities

Tohoku Electric Power is an electric utility, servicing 7.6 million individual and corporate customers in six prefectures in Tōhoku region plus Niigata Prefecture. It provides electricity at 100 V, 50 Hz, though some area use 60 Hz. Tohoku Electric Power ...

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. As a safety precaution, gas services were interrupted in Niigata Prefecture.

Seismic intensity

This chart describes the maximum perceived shaking using the

Japan Meteorological Agency seismic intensity scale The Japan Meteorological Agency (JMA) Seismic Intensity Scale (known in Japan as the Shindo seismic scale) is a seismic intensity scale used in Japan to categorize the intensity of local ground shaking caused by earthquakes. The JMA intensi ...

, or ''Shindo scale'', for the earthquake throughout the impacted area.

References

Explanatory notes Citations

External links

* {{authority control 2019 earthquakes History of Niigata Prefecture History of Yamagata Prefecture June 2019 events in Japan Earthquakes of the Reiwa period 2019 disasters in Japan