The was one of the most destructive seismic events in Japanese history. The 8.5 magnitude earthquake occurred at 19:32 (local time) on June 15, 1896, approximately off the coast of

Iwate Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture at , with a population of 1,210,534 (as of October 1, 2020). Iwate Prefecture borders Aomori Prefecture to the north, Akita Prefectu ...

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 s ...

. It resulted in two

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 ...

waves which destroyed about 9,000 homes and caused at least 22,000 deaths. The waves reached a then-record height of ; this would remain the highest on record until waves from the

2011 Tōhoku earthquake Eleven or 11 may refer to: *11 (number), the natural number following 10 and preceding 12 * one of the years 11 BC, AD 11, 1911, 2011, or any year ending in 11 Literature * ''Eleven'' (novel), a 2006 novel by British author David Llewellyn *''E ...

exceeded that height by more than . From the tsunami records the estimated tsunami's magnitude is (M_t = 8.2), much greater than expected for the seismic magnitude estimated from the observed seismic intensity (=7.2). This earthquake is now regarded as being part of a distinct class of seismic events, the tsunami earthquake.

Geology

The epicenter lies just to the west of the

Japan Trench The Japan Trench is an oceanic trench part of the Pacific Ring of Fire off northeast Japan. It extends from the Kuril Islands to the northern end of the Izu Islands, and is at its deepest. It links the Kuril–Kamchatka Trench to the north and ...

, the surface expression of the west-dipping

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...

zone. The trench forms part of 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 p ...

between the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

and

Eurasian 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 archipela ...

plates.

Magnitude

The unusual disparity between the magnitude of the earthquake and the subsequent tsunami may be due to a combination of factors: # the tsunami was caused by a slope failure triggered by the earthquake # the rupture velocity was unusually low Scientists believe the effect of subducted sediment beneath the

accretionary wedge 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 ...

was responsible for a slow rupture velocity. The effects of a 20° dipping fault along the top of the subducting plate was found to match both the observed seismic response and tsunami, but required a displacement of 10.4 m. The displacement was reduced to a more reasonable value after the extra uplift caused by the deformation of sediments in the wedge and a shallower fault dip of 10° was considered. This revised fault model gave a magnitude of =8.0–8.1. A figure much closer to the estimated actual tsunami magnitude. A magnitude of 8.5 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pa ...

has also been estimated for this event.

Tsunami

On the evening of June 15, 1896, communities along the

Sanriku coast The is a coastal region on the Pacific Ocean, extending from southern Aomori Prefecture, through Iwate Prefecture and northern Miyagi Prefecture in northeastern Honshū, which is Japan's main island. The name comes from the historical region of ...

in northern Japan were celebrating a

Shinto Shinto () is a religion from Japan. Classified as an East Asian religion by scholars of religion, its practitioners often regard it as Japan's indigenous religion and as a nature religion. Scholars sometimes call its practitioners ''Shint ...

holiday and the return of soldiers from the

First Sino-Japanese War The First Sino-Japanese War (25 July 1894 – 17 April 1895) was a conflict between China and Japan primarily over influence in Korea. After more than six months of unbroken successes by Japanese land and naval forces and the loss of the p ...

. After a small earthquake, there was little concern because it was so weak and many small tremors had also been felt in the previous few months. However, 35 minutes later the first tsunami wave struck the coast, followed by a second a few minutes later.Corkill, Edan,
Heights of survival
, ''

Japan Times ''The Japan Times'' is Japan's largest and oldest English-language daily newspaper. It is published by , a subsidiary of News2u Holdings, Inc.. It is headquartered in the in Kioicho, Chiyoda, Tokyo. History ''The Japan Times'' was launched by ...

'', 12 June 2011, pp. 9–10. The damage was particularly severe because the tsunamis coincided with high tides. Most deaths occurred in Iwate and Miyagi although casualties were also recorded from

Aomori is the capital city of Aomori Prefecture, in the Tōhoku region of Japan. , the city had an estimated population of 278,964 in 136,457 households, and a population density of 340 people per square kilometer spread over the city's total are ...

and

Hokkaido is Japan, Japan's Japanese archipelago, second largest island and comprises the largest and northernmost Prefectures of Japan, prefecture, making up its own List of regions of Japan, region. The Tsugaru Strait separates Hokkaidō from Honshu; th ...

. The power of the tsunami was great: large numbers of victims were found with broken bodies or missing limbs. As was their normal practise each evening, the local fishing fleets were all at sea when the tsunamis struck. In the deepwater, the wave went unnoticed. Only when they returned the next morning did they discover the debris and bodies. Wave heights of up to were also measured in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

. They destroyed wharves and swept several houses away.

Legacy

Preventive coastal measures were not implemented until after another tsunami struck in 1933. Due to higher levels of tsunami awareness, fewer casualties were recorded following the Sanriku earthquake. Nevertheless, the earthquake of 11 March 2011 caused a huge tsunami that resulted in thousands of deaths across the same region and the nuclear disaster at Fukushima.

References

{{Earthquakes in the 1890s (decade) Megathrust earthquakes in Japan Tsunamis in Japan Meiji-Sanriku earthquake Meiji-Sanriku earthquake Meiji-Sanriku earthquake Earthquakes in the Empire of Japan June 1896 events Tsunami earthquakes Earthquakes of the Meiji period 1896 disasters in Japan

Geology

Magnitude

Tsunami

Legacy

See also

References