:1946 Nankai earthquake

{{Short description|Great earthquake in Nankaidō, Japan measured between 8.1 and 8.4.}}

{{Infobox earthquake

|title = 1946 Nankai earthquake

|image= 1946 Nankai Earthquake (12).jpg

|local-date= {{Start date|1946|12|21}}

|local-time= 04:19 JST

|timestamp = 1946-12-20 19:19:10

|map= 1946 Nankai earthquake intensity.png

|map2 = {{Location map | Japan

| label =

| lat = 33.0

| long = 135.6

| mark = Bullseye1.png

| marksize = 40

| position = top

| width = 260

| float = center

| caption =

| relief = yes}}

|anss-url = iscgem898698

|isc-event = 898698

|caption =

|magnitude = {{Unbulleted list|{{M|w|8.1}}|{{M|s|8.3}} (ISC)}}

|depth = {{convert|30|km|abbr=on}}

|location = {{coord|33.00|N|135.60|E|display=inline,title}} {{cite web |url=https://www.ngdc.noaa.gov/hazel/view/hazards/earthquake/event-more-info/3845 |title=Significant Earthquake Information |accessdate=2024-03-21 |last=National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information.|date=1972 |publisher=NOAA National Centers for Environmental Information | doi=10.7289/V5TD9V7K}}

|countries affected = Japan

|fault = Nankai megathrust

|tsunami = Yes

|casualties = At least 1362 dead, 2600 injured and 100 missing

}}

The 1946 Nankai earthquake (昭和南海地震 Shōwa Nankai jishin) was a great earthquake in Nankaidō, Japan. It occurred on December 21, 1946, at 04:19 JST (December 20, 19:19 UTC).{{cite web|url=https://earthquake.usgs.gov/regional/world/events/1946_12_20.php |title=The 1946 Nankaido earthquake |accessdate=2008-06-29 |publisher=United States Geological Survey |date=13 March 2008 |archive-url=https://web.archive.org/web/20080601172947/http://earthquake.usgs.gov/regional/world/events/1946_12_20.php |archive-date=1 June 2008 |url-status = dead}} The earthquake measured between 8.1 and 8.4 on the moment magnitude scale, and was felt from Northern Honshū to Kyūshū. It occurred almost two years after the 1944 Tōnankai earthquake, which ruptured the adjacent part of the Nankai megathrust.

Geology

The Nankai Trough is a convergent boundary where the Philippine Sea plate is being subducted beneath the Eurasian plate. Large earthquakes have been recorded along this zone since the 7th century, with a recurrence time of 100 to 200 years.{{cite journal|url=http://www.sciencemag.org/cgi/content/abstract/289/5476/104?ck=nck|title=Subducted Seamount Imaged in the Rupture Zone of the 1946 Nankaido Earthquake|first1=S.|last1=Kodaira|first2=N.|last2=Takahashi|first3=A.|last3=Nakanishi|first4=S.|last4=Miura|first5=Y.|last5=Kaneda|journal=Science|publisher=American Association for the Advancement of Science|year=2000|volume=289|number=5476|pages=104–106|doi=10.1126/science.289.5476.104|pmid=10884221|bibcode=2000Sci...289..104K}}

Earthquake

The 1946 Nankaido earthquake was unusual in its seismological perspective, with a rupture zone estimated from long-period geodetic data that was more than twice as large as that derived from shorter period seismic data. In the center of this earthquake rupture zone, scientists used densely deployed ocean bottom seismographs to detect a subducted seamount {{Convert|13|km|mi|0}} thick by {{Convert|50|km|mi|0}} wide at a depth of {{Convert|10|km|mi|0}}. Scientists propose that this seamount might work as a barrier inhibiting brittle seismogenic rupture.

Casualties and damage

The earthquake caused extensive damage, destroying 36,000 homes in southern Honshū alone. The earthquake also caused a huge tsunami that took out another 2,100 homes with its {{Convert|5|-|6|m|ft|abbr=off|adj=on}} waves.

References

{{Reflist|refs=

{{cite journal|title=Tectonic implications of the 1944 Tonankai and the 1946 Nankaido earthquakes|url=http://www.gps.caltech.edu/uploads/File/People/kanamori/HKpepi72.pdf|first=H.|last=Kanamori|author-link=Hiroo Kanamori|journal=Physics of the Earth and Planetary Interiors|publisher=Elsevier|year=1972|volume=5|pages=130|doi=10.1016/0031-9201(72)90082-9|bibcode=1972PEPI....5..129K|access-date=2013-11-02|archive-url=https://web.archive.org/web/20131103181527/http://www.gps.caltech.edu/uploads/File/People/kanamori/HKpepi72.pdf|archive-date=2013-11-03|url-status = dead}}

}}