1611 Sanriku earthquake

Overview

At about 10:30 on December 2, 1611 (Keichō 16, 10th month, 28th day), there was a severe earthquake, and at about 14:00 (local time), this was followed by a devastating tsunami. According to old documents, the earth shook violently three times.

The estimated rupture area for the earthquake is similar to that calculated for the 1933 Sanriku earthquake.

The earthquake struck an area along the Pacific Ocean known as the Sanriku Coast, where the shaking intensity was 4–5 on the Shindo scale. The damage from the tsunami far exceeded that from the earthquake, so this is considered to be a tsunami earthquake. Consequently, the disaster caused by earthquake is also known as the "Keicho Sanriku tsunami earthquake". It would have been very similar to the 1605 Keichō Nankaidō earthquake, a tsunami earthquake in the Nankai Trough area.

Sources

The source of the earthquake was off the north coast of Sanriku. However, due to the time delay of nearly four hours before the tsunami arrived, there are questions about the exact location of the source.

Professor Kazuomi Hirakawa of Hokkaido University has found tsunami deposits on the southern part of Hokkaido and northern Sanriku from the early part of the 17th century. It is possible that the earthquake and tsunami in Sanriku was an enormous quake that resonated even in the area of the Kurile Trench off the eastern coast of Hokkaido.

Damage

The tsunami reached its maximum estimated height of about 20 m at Ōfunato, Iwate.

The tsunami struck on the east coast of Sanriku from Sendai bay in the south to southeastern Hokkaido in the north, a greater length of coastline than was affected by the 1896 tsunami. According to old documents, 1,783 people were killed in the Sendai Domain, and over 3000 horses and men in the Nanbu and Tsugaru domains. On the southern coast of Hokkaido, many Ainu were also drowned ("Hokkaido History"). Amongst the worst affected places was Ōtsuchi, with 800 deaths.

Notes

References

1. [[National Centers for Environmental Information]]. (1972). "Significant earthquake information".
2. Utsu, T.. (2004). "Catalog of Damaging Earthquakes in the World". IISEE.
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4. Atwater, B.F.. (2005). "Kuwagasaki". United States Geological Survey.
5. Kawakatsu, H.. (1983). "Triple Seismic Zone and the Regional Variation of Seismicity along the Northern Honshu Arc". [[American Geophysical Union]].
6. "17世紀、千島で巨大地震か 1500キロにわたり大津波 「慶長三陸」は、高さ20mの巨大津波が襲った道東と同一？ – MSN産経フォト".
7. "図16 1611年12月2日の慶長三陸地震の津波波高分布と震度分布（羽鳥，1975b）". Headquarters for Earthquake Research Promotion.
8. National Geophysical Data Center. "Comments for the Tsunami Event".