The 1854 Nankai earthquake occurred at about 16:00
local time on 24 December. It had a
magnitude of 8.4 and caused a damaging
tsunami. More than 30,000 buildings were destroyed and there were at least 3,000 casualties.[1]
The southern coast of Honshu runs parallel to the
Nankai Trough, which marks the
subduction of the
Philippine Sea Plate beneath the
Eurasian Plate. Movement on this
convergent plate boundary leads to many earthquakes, some of them of the
megathrust type. The Nankai megathrust has five distinct segments (A–E) that can rupture independently,[2][3] the segments have ruptured either singly or together repeatedly over the last 1300 years.[4] Megathrust earthquakes on this structure tend to occur in pairs, with a relatively short time gap between them. In addition to the two events in 1854, there were similar earthquakes in 1944 and 1946. In each case the northeastern segment ruptured before the southwestern segment.[5]
Damage
The damage due to the earthquake was severe with 5,000 houses being destroyed and 40,000 houses badly damaged. A further 6,000 homes were damaged by fire. The tsunami washed away a further 15,000 houses and a total of 3,000 people died from either the earthquake or the tsunami.[6] The death toll associated with the tsunami was less than would be expected in comparison to the
1707 tsunami, because many people had left the coastal area following the large earthquake the previous day.[7] In Hiro (now
Hirogawa),
Goryo Hamaguchi set fires using rice straw to help guide villagers to safety. This story was turned into "A living god" by the Greek-born writer
Lafcadio Hearn.[8]
Characteristics
Earthquake
Much of southwestern Honshu, Shikoku and
Kyūshū experienced shaking of 5 or more on the
JMA scale, with most of Shikoku and nearby coastal areas of
Kansai suffering an intensity of 6.[9]
Tsunami
On Shikoku, the greatest inundation heights were 7.5 m in
Mugi, 7.5 m in Kamikawaguchi (
Japanese: 上川口) of
Kuroshio,[10] 7.2 m at Asakawa on the
Tokushima coast, 7.4 m at
Usa, 8.4 m at Ōnogō in the
Susaki area, 8.3 m at Kure on the
Kōchi coast and 5 m at both Hisayoshiura and Kaizuka on the coast of
Ehime.[7]
^National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information (1972).
"Significant Earthquake Information". NOAA National Centers for Environmental Information.
doi:
10.7289/V5TD9V7K. Retrieved 30 July 2022.
^Atwater, B.F.; Musumi-Rokkaku S.;
Satake K.; Tsuji Y.; Ueda K. & Yamaguchi D.K.
"4. Kuwagasaki"(PDF). The Orphan Tsunami: Japanese clues to parent earthquake in North America. Vol. Professional Paper 1707. USGS. p. 144.
doi:
10.3133/pp1707. Retrieved 2009-11-14.
Kusumoto, Satoshi; Imai, Kentaro; Obayashi, Ryoko; Hori, Takane; Takahashi, Narumi; Ho, Tung–Cheng; Uno, Karen; Tanioka, Yuichiro; Satake, Kenji (10 June 2020). "Origin Time of the 1854 Ansei–Tokai Tsunami Estimated from Tide Gauge Records on the West Coast of North America". Seismological Research Letters. 91 (5). Seismological Society of America (SSA): 2624–2630.
Bibcode:
2020SeiRL..91.2624K.
doi:
10.1785/0220200068.
ISSN0895-0695.
S2CID225268596.