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Off shore Fault Evaluation Group

Offshore Fault Evaluation Group

photo Offshore Fault Evaluation Group
Group Leader

  • Research on off shore fault analysis and evaluation through comprehensive analysis of subsurface structure data, seafloor topography, historical materials, etc.
  • Construction of fundamental information platform for earthquake and tsunami damage mitigation

Offshore Fault Evaluation Group

While detailed studies have been carried out on active faults in land areas, information on faults in sea areas has been insufficient. Evaluation of faults which may possibly cause earthquake and tsunami damage has not progressed. As a part of “the Project for offshore fault evaluation” by the Ministry of Education, Culture, Sports, Science and Technology, the Offshore Fault Evaluation Group intends to clarify the distribution of offshore faults around Japan by collecting seafloor topography information and seismic survey data conducted by various research institutes, identifying faults using the latest technology of re-processing data and interpreting the fault in a unified method. An important information source for offshore faults is the seismic data from seismic survey. In order to organize and collect survey data conducted by different research institutes, in different periods, with different specifications and to construct a database, it is required to carefully select spatially continuous faults while checking the consistency of data such as positional information and using quality improving data such as processing noise reduction. To evaluate not only the length and the depth of faults but also their inclination, we are also constructing 3D structural models. Clarifying a fault continuity from active faults on land is also an issue. The purpose of the project is constructing source models along faults to simulate seismic motion and tsunamis, through considering the shape and mechanism of fault planes and the possibility of combination occurrences of earthquake, and utilizing the simulating models for disaster prevention and mitigation.

Fault mapping around Japan: Interim results of offshore fault mapping around the Sea of Japan. The blue lines represent the faults assumed by data analysis and evaluation from existing data, and the red lines represent those assumed as faults identified from structural discontinuity. Data processing, evaluation and interpretation is currently under way for the Sea of Japan, and fault maps of all areas around Japan will finally be constructed.