June 15, 1896 Tsunami: Sanriku, Japan

Ref #414:

1896, June 15, 19:33 (local time). A strong earthquake in Sanriku, Honshu Island, was felt over an enormous area and generated a catastrophic tsunami. According to official accounts, 10,617 buildings were washed away, 27,122 people died, and 9,247 people were injured... The tsunami was observed at least from the south of Hokkaido Island to the Bonin Islands, and also on the Hawaiian Islands and in North America. The Sanriku coast on a stretch of more than 400 km from Kinkazan Island in the south to Cape Shiriya in the north, suffered most of all.

At most places on the Sanriku coast, the tsunami began with a noticeable ebb tide. The exact time of the beginning of the ebb tide in the pleistoseismic area is unknown. According to the data of the hydrometeorological station at Miyako and the accounts of some eyewitnesses, the ebb tide began at nightfall, 15-30 minutes after the earthquake. The first tidal wave arrived immediately after 20:00. Consequently, the time difference between the beginning of the ebb tide and the arrival of the tidal wave was 30 minutes. The magnitude of the ebb tide naturally depended on the depth of the sea: in shallows, the water retreated a great distance, while at deep places, it retreated a small distance. Thus the water retreated 350 m at Horiuchi, 350-550 m at Ryoisi and Ooya, 500 m at Minatohama and 35 m at Tadaide.

Before the flood tide, a loud rumble like thunder or the noise of a squall could be heard from far at sea. The wave appeared simultaneously with the rumble on the coast of Kesen district, Iwate Prefecture, while it appeared soon after the rumble at other places. It is said that it was even heard in the prefectures of Akita and Yamagata.

It is also very difficult to establish the time of arrival of the tidal wave. The time, estimated by the hydrometeorological station at Miyako, 20:07 can be considered the most precise. According to the report of this station, the tsunami began 18 minutes after the first underground shock. A flood tide began at about 20:00, and a wave of great height, accompanied by a loud rumble, arrived at 20:07. Then the flood tides recurred six times: at 20:15, 20:32, 20:48, 20:59, 21:16 and 21:50. The second, the largest wave, washed away many people and carried homes out to sea.

The average period of oscillations on the Sanriku coast after the arrival of the tsunami was about 15 minutes. The intensity of the waves began to gradually abate after 22:00, but small oscillations in sea level were still being observed at noon of the following day. The greatest height of rise of water was registered at Yoshihama and Ryori. The second, greatest wave was 24 m high at Yoshihama and the water rose 30 m at Ryori.

On June 15, the residents of the prefectures on the Sanriku coast were celebrating a national holiday in the streets; there was no work that day. After the ebb tide, with which the tsunami began, some hurried away from the water, but the majority continued the festivities. Practically the entire population of the flooded zone, except for a few individuals miraculously spared, perished in the roller which fell on the Sanriku coast. In addition, the fishermen who had gone out to sea were saved;

Ref #150:

1896, June 15, (19:33 local time). 39.5 N, 144 E, magnitude 7.6, Sanriku. 26,360 deaths (22,000 deaths by Yamashita), more than 11,000 homes wrecked and washed away. Maximum tsunami height 38.2 m at Shirahama.

Ref #1006:

1896, June 15. 27,122 deaths and 106,170 homes destroyed by the earthquake and tsunami.

Ref #11107:

The tsunami heights from the 1896 Sanriku tsunami were measured 37 years after the event, based on eyewitness accounts. The often quoted maximum height of 38 m at Ryori– Shirahama (I133) from the 1896 Sanriku tsunami was based on this report […] the 2011 and 1896 tsunami heights ranged from 5 to 40 m