A research group led by Professor Akihisa Kitamura of Shizuoka University and Researcher Takuma Haga of the National Science Museum said that the fossils of perforated double shells found at the wave dining table in Omaezaki paired with the Nankai earthquake that occurred in 1361. (Koan) – It was clarified that it is evidence that the Tokai earthquake occurred.
The 1707 Hoei earthquake and subsequent major earthquakes that occurred in the Nankai Trough and Suruga Trough were the "Tokai Earthquake" and the "Tonankai Earthquake or Nankai Earthquake" that occurred to the west of the earthquake after several hours to several years. , Often occur in conjunction.The way such a big earthquake occurs is called "a pair occurred", and the situation where a big earthquake occurs in one of the pairs is called "half-split case (case XNUMX)".For example, if a large-scale earthquake occurs on the east side, the possibility of an earthquake occurring on the west side increases, so it is possible to prepare for a large earthquake that can occur in pairs.However, until now, sufficient information has not been obtained about earthquakes of the old age.
Therefore, this time, the group discovered a fossil of a mudstone perforated bivalve in Omaezaki, Shizuoka Prefecture (which does not move from the place where the perforation life started once), and by dating analysis, the uplift containing this fossil was caused by the 1361 Tokai earthquake. I found out that it was.From this result, it can be seen that the 650 earthquake about 1361 years ago also occurred in pairs, and it can be said that the importance of countermeasures for the "half-split case" is increasing.
This result is expected to be an important material for studying countermeasures against large earthquakes and tsunamis that will occur in the Nankai Trough and Suruga Trough, which are feared to occur in the near future.
Paper information:[Marine Geology] Japan: Evidence for the 1361 CE Tokai earthquake along the Nankai Trough
