About this database
General information
This database is a collection of measured or observed data mainly for the purpose of earthquake studies and published information on crustal stress in Japan. We are going to collect more data and information, not only on earthquake studies but on other studies.
Information about crustal stress includes data gathered from direct measurements, such as hydraulic fracturing and stress relief, and from boring cores. It also includes information about focal mechanism solutions of crustal earthquakes shallower than 20km and the anisotropy of shear-wave splitting which is strongly related with stress orientations.
About SHmax azimuth
Please refer to the following articles:
Imanishi, K., Uchide, T., Ohtani, M., Matsushita, R., and Nakai, M. (2019) Crustal Stress Map in Kanto Region, central Japan. Open-File Report of the Geological Survey of Japan, AIST, no. 681, 4p.
Imanishi, K., Uchide, T., Shiina, T., Matsushita, R., and Nakai, M. (2021) Construction of the Crustal Stress Map in Chugoku Region, western Japan. Bull. Geol. Surv. Japan, vol. 72 (1), p.23–40. doi:10.9795/bullgsj.72.23
Imanishi, K., Uchide, T., Shiina, T., Matsushita, R., and Nakai, M. (2021) Crustal Stress Map in Kanto Region, central Japan. Open-File Report of the Geological Survey of Japan, AIST, no. 720, 4p.
Uchide, T., Shiina, T., and Imanishi, K. (2022) Stress map of Japan: Detailed nationwide crustal stress field inferred from focal mechanism solutions of numerous microearthquakes. Journal of Geophysical Research Solid Earth. 127, e2022JB024036. doi:10.1029/2022JB024036
Uchide, T., Shiina, T., and Imanishi, K. (2022) Digital data of crustal stress map and focal mechanism solutions of microearthquakes for inland areas of Japan. Open-File Report of the Geological Survey of Japan, AIST, no. 738, 6p.
About azimuths of P-axis and focal mechanism solutions
Azimuths of P-axis and focal mechanism solutions (1997/10/2-2016/5/19, shallower than 20km) are compiled from JMA Unified Earthquake Catalog.
About stress measurement
This database is a collection of measurement data by stress relief and hydraulic fracturing using drilling boreholes and data by boring cores. It also contains stress measurement data that universities and research insitutes measured. About 40 articles were collected including various academic journals and proceedings.
About anisotropy
Alignments of minerals and micro-cracks in rock mass cause polarization anisotropy of shear wave velocity. We can observe the anisotropy as "shear wave splitting" by using seismic waves.
This database contains much data of "shear wave splitting" observed by universities and research institutes in Japan.
To comprehend data all over Japan, we collect data not only from international and domestic journals but also from doctral, masters' and bachelors' theses.
About active faults
The fault traces (23 July 2009 version) of Active Fault database of Japan were slightly simplified to use on the Internet.
Please check the database for details.
About annual hypocenters
The annual hypocenters between 1923 and 2020 are based on JMA Unified Earthquake Catalog.
About seamless geological map
Seamless Digital Geological Map of Japan (1:200,000) can be layered on the base map.