The islands of Japan are primarily the result of several large ocean movements occurring over hundreds of millions of years from the mid- Silurian to the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

, as a result of the subduction of the

Philippine Sea Plate The Philippine Sea Plate or the Philippine Plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part o ...

beneath the continental

Amurian 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

Okinawa Plate The Okinawa Plate, or Okinawa Platelet, is a minor continental tectonic plate in the northern and eastern hemispheres stretching from the northern end of Taiwan to the southern tip of the island of Kyūshū. The Okinawa Plate hosts typical eart ...

to the south, and subduction of the Pacific Plate under 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 ...

to the north. Japan was originally attached to the eastern coast of the

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

n continent. The subducting plates, being deeper than the Eurasian plate, pulled Japan eastward, opening 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, i ...

around 15 million years ago. The Strait of Tartary and the

Korea Strait The Korea Strait is a sea passage in East Asia between Korea and Japan, connecting the East China Sea, the Yellow Sea and the Sea of Japan in the northwest Pacific Ocean. The strait is split by the Tsushima Island into the Western Channel and ...

opened much later. Japan is situated in a

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

zone on the

Pacific Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring o ...

. Frequent low intensity earth tremors and occasional volcanic activity are felt throughout the islands. Destructive

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...

s, often resulting in

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 ...

s, occur several times per century. The most recent major quakes include the

2011 Tōhoku earthquake and tsunami The occurred at 14:46 JST (05:46 UTC) on 11 March. The magnitude 9.0–9.1 (M) undersea megathrust earthquake had an epicenter in the Pacific Ocean, east of the Oshika Peninsula of the Tōhoku region, and lasted approximately six mi ...

, the

2004 Chūetsu earthquake The occurred in Niigata Prefecture, Japan, at 17:56 local time (08:56 UTC) on Saturday, October 23, 2004. The Japan Meteorological Agency (JMA) named it the .

and the

Great Hanshin earthquake The , or Kobe earthquake, occurred on January 17, 1995, at 05:46:53 JST (January 16 at 20:46:53 UTC) in the southern part of Hyōgo Prefecture, Japan, including the region known as Hanshin. It measured 6.9 on the moment magnitude scale and ha ...

of 1995.

Geological history

Orogeny phase

The breakup of Rodinia about 750 million years ago formed the

Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During th ...

ocean, with rocks that eventually became Japan sitting on its eastern margin. In the Early Silurian (450 million years ago), the subduction of the oceanic plates started, and this process continues to the present day, forming a roughly 400 km wide orogeny at 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 ...

. Several (9 or 10) oceanic plates were completely subducted and their remains have formed paired metamorphic belts. The most recent complete subduction of a plate was that of the Izanagi Plate 95 million years ago. Currently the Philippine Sea Plate is subducting beneath the continental Amurian Plate and the Okinawa Plate to the south at a speed of 4 cm/year, forming the

Nankai Trough The is a submarine trough located south of the Nankaidō region of Japan's island of Honshu, extending approximately offshore. The underlying fault, the ''Nankai megathrust,'' is the source of the devastating Nankai megathrust earthquakes, w ...

and the

Ryukyu Trench The , also called Nansei-Shotō Trench, is a 1398 km (868 mi) long oceanic trench located along the southeastern edge of Japan's Ryukyu Islands in the Philippine Sea in the Pacific Ocean, between northeastern Taiwan and southern Japan. ...

. The Pacific Plate is subducting under the Okhotsk Plate to the north at a speed of 10 cm/year. The early stages of subduction-accretion have recycled the continental crust margin several times, leaving the majority of the modern

Japanese archipelago The Japanese archipelago (Japanese: 日本列島, ''Nihon rettō'') is a group of 6,852 islands that form the country of Japan, as well as the Russian island of Sakhalin. It extends over from the Sea of Okhotsk in the northeast to the East Chin ...

composed of rocks formed in the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

period or later.

Island arc phase

Around 23 million years ago, western Japan was a coastal region of the Eurasia continent. The subducting plates, being deeper than the Eurasian plate, pulled parts of Japan which become modern

Chūgoku region The , also known as the region, is the westernmost region of Honshū, the largest island of Japan. It consists of the prefectures of Hiroshima, Okayama, Shimane, Tottori, and Yamaguchi. In 2010, it had a population of 7,563,428. History ''C ...

and Kyushu eastward, opening the Sea of Japan (simultaneously with the Sea of Okhotsk) around 15-20 million years ago, with likely freshwater lake state before the sea has rushed in. Around 16 million years ago, in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

period, a peninsula attached to the eastern coast of the

n continent was well formed. About 11 million years before present, the parts of Japan which become modern Tōhoku and

Hokkaido is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The lar ...

were gradually uplifted from the seafloor, and terranes of Chūbu region were gradually accreted from the colliding island chains. The Strait of Tartary and the Korea Strait opened much later, about 2 million years ago. At the same time, a severe subduction of

Fossa Magna Fossa Magna is a great rift lowland in Japan. It is often confused with Itoigawa-Shizuoka Tectonic Line. However, Itoigawa-Shizuoka Tectonic Line is a line; Fossa Magna is an area. Fossa Magna is Latin for "great crevasse". This name was given by ...

graben have formed the

Kantō Plain The is the largest plain in Japan, and is located in the Kantō region of central Honshū. The total area of 17,000 km2 covers more than half of the region extending over Tokyo, Saitama Prefecture, Kanagawa Prefecture, Chiba Prefecture, ...

Current state

General information

Overall, the geological composition of Japan is poorly understood. The Japanese islands are formed of several geological units parallel to the subduction front. The parts of islands facing oceanic plates are typically younger and display a larger proportion of volcanic products, while the parts facing the Sea of Japan are mostly heavily faulted and folded sedimentary deposits. In north-west Japan, the thick quaternary deposits make determination of the geological history especially difficult.

Geological structure

The Japanese islands are divided into three major geological domains: * Northeastern Japan, north of (which had high volcanic activity 14-17 million years before present) ** Idosawa Fault ** Senya Fault ** Hidaka Mountains **

Kitakami Mountains is a mountain range in northeastern Honshu, in the Tōhoku region of northern Japan.Kitakami Moun ...

Ōu Mountains The are a mountain range in the Tōhoku region of Honshū, Japan. The range is the longest range in Japan and stretches south from the Natsudomari Peninsula of Aomori Prefecture to the Nasu volcanoes at the northern boundary of the Kantō ...

* Central Japan, between Tanakura fault and

Itoigawa-Shizuoka Tectonic Line , also Ito Shizu Sen (糸静線) is a major fault on Honshu island that runs from the city of Itoigawa, Niigata Prefecture, through Lake Suwa to the city of Shizuoka in Shizuoka Prefecture. It is often confused with the Fossa Magna (Great Fis ...

. **

graben ** Tanna Fault **

Bōsō Hill Range The is a mountain range on the Bōsō Peninsula of Chiba Prefecture, Japan. The highest point in the Bōsō Mountain Range is at Mount Atago, with an altitude of . The hill range runs from roughly in a line from Mobara or Ōamishirasato to Ki ...

* Southwestern Japan, south of

. The Southwestern Japan is further subdivided into several metamorphic belts stretched along

Japan Median Tectonic Line , also Median Tectonic Line (MTL), is Japan's longest fault system. The MTL begins near Ibaraki Prefecture, where it connects with the Itoigawa-Shizuoka Tectonic Line (ISTL) and the Fossa Magna. It runs parallel to Japan's volcanic arc, passing ...

. The parts of Japan north of

("Inner Zone") contains many

granitoid A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

fragments dating from Paleogene to

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

period intruding the older material, while south of the line ("Outer Zone") is mostly

accretionary complex An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the d ...

es of

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

period or younger. ** Urasoko fault **

Fukozu Fault is a fault in Aichi Prefecture of Japan, which was responsible for the 1945 Mikawa earthquake. It extends some 28 km (10 km under the sea) to Nishio is a city located in Aichi Prefecture, in the Chūbu region of Japan. , the city h ...

Neodani Fault is a left lateral slip fault in central Japan, Gifu Prefecture, which ruptured causing the 1891 Mino–Owari earthquake (otherwise known as the Nōbi earthquake) in 1891. It caused a 6m vertical offset and 8m left lateral offset, and ruptured ove ...

Nojima Fault is a fault that was responsible for the Great Hanshin earthquake of 1995 (Kobe Quake). It cuts across Awaji Island, Japan and it is a branch of the Japan Median Tectonic Line which runs the length of the southern half of Honshu island. The fa ...

**Hida orogenic belt ( Hida Mountains and

Ryōhaku Mountains The are a mountain range spanning Gifu, Toyama, Ishikawa, Fukui and Shiga prefectures in Japan. It is divided into the Kaetsu Mountains (加越山地 ''Kaetsu Sanchi''), whose major peak is Mount Haku, and the Etsumi Mountains (越美山地 ''Et ...

) **Sangun orogenic belt **Maizuru orogenic belt **Tanba-mino orogenic belt **Ryoke orogenic belt **Shimanto orogenic beltA. Taira, H. Okada, J. H. McD. Whitaker & A. J. Smith, The Shimanto Belt of Japan: Cretaceous-lower Miocene active-margin sedimentation
/ref> **Sambagawa orogenic belt **Chichibu orogenic belt **Sambosan orogenic belt ** Beppu–Shimabara graben

Research

The Geology of Japan is handled mostly by , with the following major periodicals: * - since 1893 * - since 1968 * - since 1998

Geological hazards

Japan is in a volcanic zone on the Pacific Ring of Fire. Frequent low intensity earth tremors and occasional volcanic activity are felt throughout the islands. Destructive earthquakes, often resulting in tsunamis, occur several times a century. The most recent major quakes include the 2011 Tōhoku earthquake and tsunami, the 2004 Chūetsu earthquake and the Great Hanshin earthquake of 1995.

References

External links

Geological Survey of Japan - English homepageGeological Journal of Japan - English homepage
*

National Archives of Japan The preserve Japanese government documents and historical records and make them available to the public. Although Japan's reverence for its unique history and art is well documented and illustrated by collections of art and documents, there is a ...

''Tatoroyama no ki,'' survey of limestone cave in Mount Tatoro in Kozuke Province, 1837 (''Tenpo 8'').
{{Asia topic, Geology of