1983 earthquake and tsunami centered off the coast of Akita Prefecture, Japan
The
1983 Sea of Japan earthquake
(
Japanese
:
日本海中部地震
) occurred on May 26, 1983 at 11:59:57 local time (02:59:57
UTC
). It had a magnitude of 7.8 on the
moment magnitude scale
. It occurred in the
Sea of Japan
, about 100 km west of the coast of
Noshiro
in
Akita Prefecture
,
Japan
. Out of the 104 fatalities, all but four were killed by the resulting
tsunami
, which struck communities along the coast, especially
Aomori
and
Akita Prefectures
and the east coast of
Noto Peninsula
. Images of the tsunami hitting the fishing harbor of
Wajima
on Noto Peninsula were broadcast on TV. The waves exceeded 10 meters (33 ft) in some areas. Three of the fatalities were along the east coast of
South Korea
(whether
North Korea
was affected is not known). The tsunami also hit
Okushiri Island
, the site of a more deadly
tsunami
10 years later.
Tectonic setting
[
edit
]
The northwestern side of Honshu lies on the southeastern margin of the
Sea of Japan
, an area of
oceanic crust
created by
back-arc spreading
from the
late Oligocene
to
middle Miocene
. The
extensional tectonics
associated with the spreading formed a series of N-S trending
extensional faults
and associated
basins
. Currently the area is being deformed by
contractional tectonics
, causing
inversion
of these earlier basins, forming
anticlinal
structures.
[3]
It has been suggested that the northwestern coast of Honshu represents an incipient subduction zone,
[1]
but there remain significant uncertainties about the existence of the
Okhotsk Plate
and the nature and precise location of its boundary in the Sea of Japan, if it does exist.
[4]
[5]
Earthquake
[
edit
]
The earthquake lasted for about 60 seconds. The
focal mechanism
indicates reverse faulting and the distribution of aftershocks is consistent with movement on a thrust plane dipping at 30° to the east. The rupture involved two separate faults, the more northerly of which trends NNW-SSE and the more southerly SSW-NNE. The rupture began on the southern fault before continuing on the northern fault after a delay of ten seconds.
[6]
The maximum perceived intensity was V on the
JMA scale
(VIII on the
Mercalli intensity scale
).
[2]
Tsunami
[
edit
]
The first wave of the tsunami struck the coast about 12 minutes after the earthquake, with a maximum run-up height of 14.9 m (49 ft) recorded on the
Oga Peninsula
.
[7]
The initial models of the earthquake were unable to reproduce the short time interval between the shock and the first wave arrival at the coast. The possibility that the faults dipped to the west, which would have brought the tsunami source closer to the coast, was inconsistent with seismic data and slow aseismic slip on the southern fault immediately before the mainshock has been proposed as an explanation.
[6]
Tsunami deposits
associated with this earthquake have been recognised onshore, on the coast and in the Sea of Japan.
[8]
Offshore both mass failure deposits and turbidites have been observed that are dated to later than 1954 from high
caesium-137
levels in the overlying sediments.
[9]
Damage
[
edit
]
Much of the earthquake damage was due to
soil liquefaction
, causing the collapse of houses and a number of road and rail accidents. The degree of liquefaction was the worst seen in Japan since the
1964 Niigata earthquake
. The greatest effects were observed in areas underlain by loose
Holocene
aeolian and fluvial sands.
[10]
Four people were killed by the effects of the earthquake shaking.
[2]
Tsunami warnings were issued 14 minutes after the earthquake, but many parts of the nearby coast were struck before any action could be taken.
[7]
Many people were struck by the first wave either on the shoreline or on offshore building sites and there were a hundred deaths. The tsunami caused widespread damage to coastal defences, which had been designed for storms rather than tsunamis. The tsunami reached the coast of South Korea about 1?1½ hours after the earthquake, causing the death of three people.
[7]
See also
[
edit
]
References
[
edit
]
- ^
a
b
Kanamori, H.; Astiz L. (1985).
"The 1983 Akita-Oki Earthquake (
Mw
=7.8) and its Implications for Systematics of Subduction Earthquakes"
(PDF)
.
Earthquake Prediction Research
.
3
: 305?317. Archived from
the original
(PDF)
on 11 December 2013
. Retrieved
21 June
2012
.
- ^
a
b
c
National Geophysical Data Center
.
"Comments for the Significant Earthquake"
. Retrieved
21 June
2012
.
- ^
Sato, H.; Yoshida T.; Takaya I.; Sato T.; Ikeda Y. & Umino N. (2004).
"Late Cenozoic tectonic development of the back arc region of central northern Honshu, Japan, revealed by recent deep seismic profiling"
.
Journal of the Japanese Association for Petroleum Technology
.
69
(2): 145?154.
doi
:
10.3720/japt.69.145
.
ISSN
0370-9868
.
- ^
Seno, Tetsuzo; Sakurai, Taro; Stein, Seth (1996). "Can the Okhotsk plate be discriminated from the North American plate?".
Journal of Geophysical Research
.
101
(B5): 11305?11315.
Bibcode
:
1996JGR...10111305S
.
doi
:
10.1029/96JB00532
.
- ^
Apel, E. V.; Burgmann, R.; Steblov, G.; Vasilenko, N.; King, R.; Prytkov, A (2006), "Independent active microplate tectonics of northeast Asia from GPS velocities and block modeling",
Geophysical Research Letters
,
33
(L11303): L11303,
Bibcode
:
2006GeoRL..3311303A
,
doi
:
10.1029/2006GL026077
- ^
a
b
Shuto, N.; Chida K. & Imamura F. (1995).
"Generation mechanism of the first wave of the Nihonkai-Chubu earthquake tsunami"
. In Tsuchiya Y. & Shuto N. (eds.).
Tsunami: Progress in Prediction, Disaster Prevention, and Warning
. Advances in Natural and Technological Hazards Research. Vol. 4. Springer. pp. 37?53.
ISBN
978-0-7923-3483-5
. Retrieved
21 June
2012
.
- ^
a
b
c
National Geophysical Data Center
.
"Comments for the Tsunami Event"
. Retrieved
21 June
2012
.
- ^
National Geophysical Data Center
.
"Tsunami Event associated with Tsunami Deposits"
. Retrieved
21 June
2012
.
- ^
Nakajima, T.; Kanai Y. (2000). "Sedimentary features of seismoturbidites triggered by the 1983 and older historical earthquakes in the eastern margin of the Japan Sea".
Sedimentary Geology
.
135
(1?4): 1?19.
Bibcode
:
2000SedG..135....1N
.
doi
:
10.1016/S0037-0738(00)00059-2
.
- ^
Tohno, I.; Shamoto Y. (1986).
"Liquefaction damage to the ground during the Nihonkai-Chubu (Japan Sea) earthquake in Aomori Prefecture, Tohoku, Japan"
(PDF)
.
Natural Disaster Science
.
8
(1): 85?116
. Retrieved
21 June
2012
.
External links
[
edit
]
|
---|
- 1983 Popayan
(5.5, March 31)
- Coalinga
(6.5, May 2)
- Noshiro
(7.8, May 26)
†
- Biga
(6.1, July 5)
- Luzon
(6.5, August 17)
- Kopaonik
(5.3, September 10)
- Borah Peak
(6.9, October 28)
- Erzurum
(6.9, October 30)
†
‡
- Heze
(5.7, November 7)
†
- Kaoiki
(6.7, November 16)
- Chagos Archipelago
(7.7, November 30)
- Hindu Kush
(7.4, December 30)
- Liege
(4.7, November 8)
|
†
indicates earthquake resulting in at least 30 deaths
‡
indicates the deadliest earthquake of the year
|
|
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Historical
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20th century
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21st century
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Related articles
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