11:00 AM - 11:15 AM
[SSS13-02] Reexamination of Uplift at the Murotsu Port based on the Kubono Documents
Keywords:Nankai Earthquake, long-term evaluation, Time-Predictable model, crustal deformation, Kubono documents
The Earthquake Research Council issued a long-term evaluation of earthquakes along the Nankai Trough
in May, 2013. Its main point is that there is a 60 –70 % of chance of earthquake during the next 30 years.
Several critical comments were presented before and after its announcement, especially on the adoption
of the Time-Predictable model by Shimazaki and Nakata (1980) to obtain recurrence interval of the next earthquake. Shimazaki and Nakata computed recurrence interval using coseismic uplift at the Murotsu port documented by Imamura (1930), who referred to old documents by the Kobono family.
We examined this Kubono documents and found serious drawbacks as follows;
1) Tidal data before and after the 1707 Hoei earthquake were not original but a copy from other documents by local officials who were in charge of measurements.
2) Therefore, detailed information of measurements was not transferred.
3) Construction works by thousands of workers were made every year since its opening in 1679.
4) The time of measurement before the Hoei earthquake is unclear.
5) No detailed information s not found related to measurements of coseismic uplift of the 1854 Ansei earthquake.
6) There is a problem for standard of length.
7) Imamura may have not examined when he published report in 1930.
Furthermore, ERC gave high credibility on these measurements without thorough examination of the uplift data. Therefore, the evaluation should be reexamined taking the above points into account.
We thank Dr. Keita Mizumatsu, Kochi Castle Museum of History, for his unselfish support on the survey of the Kubono Documents. We also thank the Text Database of Historical Materials on Earthquakes and
Volcanoes of the Collaborative Research Organization for Historical Materials on Earthquakes and
Volcanoes, The University of Tokyo.
in May, 2013. Its main point is that there is a 60 –70 % of chance of earthquake during the next 30 years.
Several critical comments were presented before and after its announcement, especially on the adoption
of the Time-Predictable model by Shimazaki and Nakata (1980) to obtain recurrence interval of the next earthquake. Shimazaki and Nakata computed recurrence interval using coseismic uplift at the Murotsu port documented by Imamura (1930), who referred to old documents by the Kobono family.
We examined this Kubono documents and found serious drawbacks as follows;
1) Tidal data before and after the 1707 Hoei earthquake were not original but a copy from other documents by local officials who were in charge of measurements.
2) Therefore, detailed information of measurements was not transferred.
3) Construction works by thousands of workers were made every year since its opening in 1679.
4) The time of measurement before the Hoei earthquake is unclear.
5) No detailed information s not found related to measurements of coseismic uplift of the 1854 Ansei earthquake.
6) There is a problem for standard of length.
7) Imamura may have not examined when he published report in 1930.
Furthermore, ERC gave high credibility on these measurements without thorough examination of the uplift data. Therefore, the evaluation should be reexamined taking the above points into account.
We thank Dr. Keita Mizumatsu, Kochi Castle Museum of History, for his unselfish support on the survey of the Kubono Documents. We also thank the Text Database of Historical Materials on Earthquakes and
Volcanoes of the Collaborative Research Organization for Historical Materials on Earthquakes and
Volcanoes, The University of Tokyo.