Nankai Trough Evaluation Study Group "No special changes have been observed" July 7, 19:33
The regular study group, which evaluates the possibility of a huge earthquake in the Nankai Trough, summarized the view that "no particular change has been observed."
A study group made by experts analyzed the data by holding a regular meeting again by exchanging documents due to the influence of the new coronavirus.
In the hypocenter region of the Nankai Trough and its surroundings, it is a small-scale "deep low frequency earthquake" with the epicenter near the border of the plate in western Shikoku from the 4th to the 6th of last month and in the Tokai since 29th of the last month. It is said that several earthquakes were observed, and along with this, several "strain gauges" in the surrounding area and tilt data also showed slight changes.
This is thought to be due to the "short-term slow slip" in which the boundary of the plate deep in the hypocenter region moves slowly over a relatively short period.
In addition, since last year, a slight crustal movement different from the previous trend has been observed in central Shikoku and the Shima Peninsula.
This is thought to be due to "long-term slow slip", which is a phenomenon in which the borders of the plates move slowly each year, and both are phenomena that have been repeatedly observed until now. No particular changes have been observed that are considered to have a relatively higher probability of occurrence than in normal times."