[MIS02-P07] ICDP DSeis 4: Drilling, core logging, and in-hole geophysical logging of ICDP DSeis drilling into the M5.5 aftershock zones in a South African gold mines.
In JpGU 2019 meeting, nine papers (ICDP DSeis 1-9) report on the outcomes. This poster (ICDP DSeis 4) compiles drilling, core logging, and in-hole geophysical logging of ICDP DSeis drilling into the M5.5 aftershock zones in a South African gold mines. A core orientation tool was used during drilling but not 100% reliable because there was a case that a bottom line in a core run was different by more than 90 degrees from the bottom line in the next core run. We elaborated to compare OTV image with core to carefully check the core orientation. The modified core orientation allowed us to modify the maximum stress direction that Ishida et al. (2018) measured. We could confirm good consistency with borehole breakout analysis (Richenbacher 2018; ETH master thesis). We will report on other associated outcomes. Refer other papers (ICDP DSeis 1-3, 5-9) for other related outcomes.
Acknowledgement: The DSeis team includes co-authors of the papers ICDP DSeis 2-9 and members shown at https://www.icdp-online.org/projects/world/africa/orkney-s-africa/details/. We thank Harmony Gold, Anglogold Ashanthi, Lesedi, Digital Surveying, OHMS, Seismogen, 3D Geoscience. ICDP, JSPS, SA NRF, MEXT Japan, US NSF, German DRF, and Ritsumeikan Univ. financially support the project.